Merge pull request #8 from ivanov/ipython-dir-default

main change is adding a what's new entry

docs/source/whatsnew/pr/no-xdg.rst

@@ -0,0 +1,5 b''
+* Previous versions of IPython on Linux would use the XDG config directory,
+  creating :file:`~/.config/ipython` by default. We have decided to go
+  back to :file:`~/.ipython` for consistency among systems. IPython will
+  issue a warning if it finds the XDG location, and will move it to the new
+  location if there isn't already a directory there.

IPython/core/usage.py

@@ -1,571 +1,570 b''
 # -*- coding: utf-8 -*-
 """Usage information for the main IPython applications.
 """
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2008-2011  The IPython Development Team
 #  Copyright (C) 2001-2007 Fernando Perez. <[e-mail]>
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 import sys
 from IPython.core import release
 
 cl_usage = """\
 =========
  IPython
 =========
 
 Tools for Interactive Computing in Python
 =========================================
 
     A Python shell with automatic history (input and output), dynamic object
     introspection, easier configuration, command completion, access to the
     system shell and more.  IPython can also be embedded in running programs.
 
 
 Usage
 
     ipython [subcommand] [options] [-c cmd | -m mod | file] [--] [arg] ...
 
     If invoked with no options, it executes the file and exits, passing the
     remaining arguments to the script, just as if you had specified the same
     command with python. You may need to specify `--` before args to be passed
     to the script, to prevent IPython from attempting to parse them. If you
     specify the option `-i` before the filename, it will enter an interactive
     IPython session after running the script, rather than exiting. Files ending
     in .py will be treated as normal Python, but files ending in .ipy can
     contain special IPython syntax (magic commands, shell expansions, etc.).
 
     Almost all configuration in IPython is available via the command-line. Do
     `ipython --help-all` to see all available options.  For persistent
     configuration, look into your `ipython_config.py` configuration file for
     details.
 
     This file is typically installed in the `IPYTHONDIR` directory, and there
     is a separate configuration directory for each profile. The default profile
-    directory will be located in $IPYTHONDIR/profile_default. For Linux users,
-    IPYTHONDIR defaults to `$HOME/.config/ipython`, and for other Unix systems
-    to `$HOME/.ipython`.  For Windows users, $HOME resolves to C:\\Documents
-    and Settings\\YourUserName in most instances.
+    directory will be located in $IPYTHONDIR/profile_default. IPYTHONDIR
+    defaults to to `$HOME/.ipython`.  For Windows users, $HOME resolves to
+    C:\\Documents and Settings\\YourUserName in most instances.
 
     To initialize a profile with the default configuration file, do::
 
       $> ipython profile create
 
     and start editing `IPYTHONDIR/profile_default/ipython_config.py`
 
     In IPython's documentation, we will refer to this directory as
     `IPYTHONDIR`, you can change its default location by creating an
     environment variable with this name and setting it to the desired path.
 
     For more information, see the manual available in HTML and PDF in your
     installation, or online at http://ipython.org/documentation.html.
 """
 
 interactive_usage = """
 IPython -- An enhanced Interactive Python
 =========================================
 
 IPython offers a combination of convenient shell features, special commands
 and a history mechanism for both input (command history) and output (results
 caching, similar to Mathematica). It is intended to be a fully compatible
 replacement for the standard Python interpreter, while offering vastly
 improved functionality and flexibility.
 
 At your system command line, type 'ipython -h' to see the command line
 options available. This document only describes interactive features.
 
 MAIN FEATURES
 -------------
 
 * Access to the standard Python help. As of Python 2.1, a help system is
   available with access to object docstrings and the Python manuals. Simply
   type 'help' (no quotes) to access it.
 
 * Magic commands: type %magic for information on the magic subsystem.
 
 * System command aliases, via the %alias command or the configuration file(s).
 
 * Dynamic object information:
 
   Typing ?word or word? prints detailed information about an object.  If
   certain strings in the object are too long (docstrings, code, etc.) they get
   snipped in the center for brevity.
 
   Typing ??word or word?? gives access to the full information without
   snipping long strings. Long strings are sent to the screen through the less
   pager if longer than the screen, printed otherwise.
 
   The ?/?? system gives access to the full source code for any object (if
   available), shows function prototypes and other useful information.
 
   If you just want to see an object's docstring, type '%pdoc object' (without
   quotes, and without % if you have automagic on).
 
   Both %pdoc and ?/?? give you access to documentation even on things which are
   not explicitely defined. Try for example typing {}.get? or after import os,
   type os.path.abspath??. The magic functions %pdef, %source and %file operate
   similarly.
 
 * Completion in the local namespace, by typing TAB at the prompt.
 
   At any time, hitting tab will complete any available python commands or
   variable names, and show you a list of the possible completions if there's
   no unambiguous one. It will also complete filenames in the current directory.
 
   This feature requires the readline and rlcomplete modules, so it won't work
   if your Python lacks readline support (such as under Windows).
 
 * Search previous command history in two ways (also requires readline):
 
   - Start typing, and then use Ctrl-p (previous,up) and Ctrl-n (next,down) to
     search through only the history items that match what you've typed so
     far. If you use Ctrl-p/Ctrl-n at a blank prompt, they just behave like
     normal arrow keys.
 
   - Hit Ctrl-r: opens a search prompt. Begin typing and the system searches
     your history for lines that match what you've typed so far, completing as
     much as it can.
 
   - %hist: search history by index (this does *not* require readline).
 
 * Persistent command history across sessions.
 
 * Logging of input with the ability to save and restore a working session.
 
 * System escape with !. Typing !ls will run 'ls' in the current directory.
 
 * The reload command does a 'deep' reload of a module: changes made to the
   module since you imported will actually be available without having to exit.
 
 * Verbose and colored exception traceback printouts. See the magic xmode and
   xcolor functions for details (just type %magic).
 
 * Input caching system:
 
   IPython offers numbered prompts (In/Out) with input and output caching. All
   input is saved and can be retrieved as variables (besides the usual arrow
   key recall).
 
   The following GLOBAL variables always exist (so don't overwrite them!):
   _i: stores previous input.
   _ii: next previous.
   _iii: next-next previous.
   _ih : a list of all input _ih[n] is the input from line n.
 
   Additionally, global variables named _i<n> are dynamically created (<n>
   being the prompt counter), such that _i<n> == _ih[<n>]
 
   For example, what you typed at prompt 14 is available as _i14 and _ih[14].
 
   You can create macros which contain multiple input lines from this history,
   for later re-execution, with the %macro function.
 
   The history function %hist allows you to see any part of your input history
   by printing a range of the _i variables. Note that inputs which contain
   magic functions (%) appear in the history with a prepended comment. This is
   because they aren't really valid Python code, so you can't exec them.
 
 * Output caching system:
 
   For output that is returned from actions, a system similar to the input
   cache exists but using _ instead of _i. Only actions that produce a result
   (NOT assignments, for example) are cached. If you are familiar with
   Mathematica, IPython's _ variables behave exactly like Mathematica's %
   variables.
 
   The following GLOBAL variables always exist (so don't overwrite them!):
   _ (one underscore): previous output.
   __ (two underscores): next previous.
   ___ (three underscores): next-next previous.
 
   Global variables named _<n> are dynamically created (<n> being the prompt
   counter), such that the result of output <n> is always available as _<n>.
 
   Finally, a global dictionary named _oh exists with entries for all lines
   which generated output.
 
 * Directory history:
 
   Your history of visited directories is kept in the global list _dh, and the
   magic %cd command can be used to go to any entry in that list.
 
 * Auto-parentheses and auto-quotes (adapted from Nathan Gray's LazyPython)
 
   1. Auto-parentheses
         
      Callable objects (i.e. functions, methods, etc) can be invoked like
      this (notice the commas between the arguments)::
        
          In [1]: callable_ob arg1, arg2, arg3
        
      and the input will be translated to this::
        
          callable_ob(arg1, arg2, arg3)
        
      This feature is off by default (in rare cases it can produce
      undesirable side-effects), but you can activate it at the command-line
      by starting IPython with `--autocall 1`, set it permanently in your
      configuration file, or turn on at runtime with `%autocall 1`.
 
      You can force auto-parentheses by using '/' as the first character
      of a line.  For example::
        
           In [1]: /globals             # becomes 'globals()'
        
      Note that the '/' MUST be the first character on the line!  This
      won't work::
        
           In [2]: print /globals    # syntax error
 
      In most cases the automatic algorithm should work, so you should
      rarely need to explicitly invoke /. One notable exception is if you
      are trying to call a function with a list of tuples as arguments (the
      parenthesis will confuse IPython)::
        
           In [1]: zip (1,2,3),(4,5,6)  # won't work
        
      but this will work::
        
           In [2]: /zip (1,2,3),(4,5,6)
           ------> zip ((1,2,3),(4,5,6))
           Out[2]= [(1, 4), (2, 5), (3, 6)]
 
      IPython tells you that it has altered your command line by
      displaying the new command line preceded by -->.  e.g.::
        
           In [18]: callable list
           -------> callable (list)
 
   2. Auto-Quoting
     
      You can force auto-quoting of a function's arguments by using ',' as
      the first character of a line.  For example::
        
           In [1]: ,my_function /home/me   # becomes my_function("/home/me")
 
      If you use ';' instead, the whole argument is quoted as a single
      string (while ',' splits on whitespace)::
        
           In [2]: ,my_function a b c   # becomes my_function("a","b","c")
           In [3]: ;my_function a b c   # becomes my_function("a b c")
 
      Note that the ',' MUST be the first character on the line!  This
      won't work::
        
           In [4]: x = ,my_function /home/me    # syntax error
 """
 
 interactive_usage_min =  """\
 An enhanced console for Python.
 Some of its features are:
 - Readline support if the readline library is present.
 - Tab completion in the local namespace.
 - Logging of input, see command-line options.
 - System shell escape via ! , eg !ls.
 - Magic commands, starting with a % (like %ls, %pwd, %cd, etc.)
 - Keeps track of locally defined variables via %who, %whos.
 - Show object information with a ? eg ?x or x? (use ?? for more info).
 """
 
 quick_reference = r"""
 IPython -- An enhanced Interactive Python - Quick Reference Card
 ================================================================
 
 obj?, obj??      : Get help, or more help for object (also works as
                    ?obj, ??obj).
 ?foo.*abc*       : List names in 'foo' containing 'abc' in them.
 %magic           : Information about IPython's 'magic' % functions.
 
 Magic functions are prefixed by % or %%, and typically take their arguments
 without parentheses, quotes or even commas for convenience.  Line magics take a
 single % and cell magics are prefixed with two %%.
 
 Example magic function calls:
 
 %alias d ls -F   : 'd' is now an alias for 'ls -F'
 alias d ls -F    : Works if 'alias' not a python name
 alist = %alias   : Get list of aliases to 'alist'
 cd /usr/share    : Obvious. cd -<tab> to choose from visited dirs.
 %cd??            : See help AND source for magic %cd
 %timeit x=10     : time the 'x=10' statement with high precision.
 %%timeit x=2**100
 x**100           : time 'x*100' with a setup of 'x=2**100'; setup code is not
                    counted.  This is an example of a cell magic.
 
 System commands:
 
 !cp a.txt b/     : System command escape, calls os.system()
 cp a.txt b/      : after %rehashx, most system commands work without !
 cp ${f}.txt $bar : Variable expansion in magics and system commands
 files = !ls /usr : Capture sytem command output
 files.s, files.l, files.n: "a b c", ['a','b','c'], 'a\nb\nc'
 
 History:
 
 _i, _ii, _iii    : Previous, next previous, next next previous input
 _i4, _ih[2:5]    : Input history line 4, lines 2-4
 exec _i81        : Execute input history line #81 again
 %rep 81          : Edit input history line #81
 _, __, ___       : previous, next previous, next next previous output
 _dh              : Directory history
 _oh              : Output history
 %hist            : Command history. '%hist -g foo' search history for 'foo'
 
 Autocall:
 
 f 1,2            : f(1,2)  # Off by default, enable with %autocall magic.
 /f 1,2           : f(1,2) (forced autoparen)
 ,f 1 2           : f("1","2")
 ;f 1 2           : f("1 2")
 
 Remember: TAB completion works in many contexts, not just file names
 or python names.
 
 The following magic functions are currently available:
 
 """
 
 gui_reference = """\
 ===============================
  The graphical IPython console
 ===============================
 
 This console is designed to emulate the look, feel and workflow of a terminal
 environment, while adding a number of enhancements that are simply not possible
 in a real terminal, such as inline syntax highlighting, true multiline editing,
 inline graphics and much more.
 
 This quick reference document contains the basic information you'll need to
 know to make the most efficient use of it.  For the various command line
 options available at startup, type ``ipython qtconsole --help`` at the command line.
 
 
 Multiline editing
 =================
 
 The graphical console is capable of true multiline editing, but it also tries
 to behave intuitively like a terminal when possible.  If you are used to
 IPython's old terminal behavior, you should find the transition painless, and
 once you learn a few basic keybindings it will be a much more efficient
 environment.
 
 For single expressions or indented blocks, the console behaves almost like the
 terminal IPython: single expressions are immediately evaluated, and indented
 blocks are evaluated once a single blank line is entered::
 
     In [1]: print "Hello IPython!"  # Enter was pressed at the end of the line
     Hello IPython!
 
     In [2]: for i in range(10):
        ...: 	print i,
        ...:
     0 1 2 3 4 5 6 7 8 9
 
 If you want to enter more than one expression in a single input block
 (something not possible in the terminal), you can use ``Control-Enter`` at the
 end of your first line instead of ``Enter``.  At that point the console goes
 into 'cell mode' and even if your inputs are not indented, it will continue
 accepting arbitrarily many lines until either you enter an extra blank line or
 you hit ``Shift-Enter`` (the key binding that forces execution).  When a
 multiline cell is entered, IPython analyzes it and executes its code producing
 an ``Out[n]`` prompt only for the last expression in it, while the rest of the
 cell is executed as if it was a script.  An example should clarify this::
 
     In [3]: x=1  # Hit C-Enter here
        ...: y=2  # from now on, regular Enter is sufficient
        ...: z=3
        ...: x**2  # This does *not* produce an Out[] value
        ...: x+y+z  # Only the last expression does
        ...:
     Out[3]: 6
 
 The behavior where an extra blank line forces execution is only active if you
 are actually typing at the keyboard each line, and is meant to make it mimic
 the IPython terminal behavior.  If you paste a long chunk of input (for example
 a long script copied form an editor or web browser), it can contain arbitrarily
 many intermediate blank lines and they won't cause any problems.  As always,
 you can then make it execute by appending a blank line *at the end* or hitting
 ``Shift-Enter`` anywhere within the cell.
 
 With the up arrow key, you can retrieve previous blocks of input that contain
 multiple lines.  You can move inside of a multiline cell like you would in any
 text editor.  When you want it executed, the simplest thing to do is to hit the
 force execution key, ``Shift-Enter`` (though you can also navigate to the end
 and append a blank line by using ``Enter`` twice).
 
 If you've edited a multiline cell and accidentally navigate out of it with the
 up or down arrow keys, IPython will clear the cell and replace it with the
 contents of the one above or below that you navigated to.  If this was an
 accident and you want to retrieve the cell you were editing, use the Undo
 keybinding, ``Control-z``.
 
 
 Key bindings
 ============
 
 The IPython console supports most of the basic Emacs line-oriented keybindings,
 in addition to some of its own.
 
 The keybinding prefixes mean:
 
 - ``C``: Control
 - ``S``: Shift
 - ``M``: Meta (typically the Alt key)
 
 The keybindings themselves are:
 
 - ``Enter``: insert new line (may cause execution, see above).
 - ``C-Enter``: *force* new line, *never* causes execution.
 - ``S-Enter``: *force* execution regardless of where cursor is, no newline added.
 - ``Up``: step backwards through the history.
 - ``Down``: step forwards through the history.
 - ``S-Up``: search backwards through the history (like ``C-r`` in bash).
 - ``S-Down``: search forwards through the history.
 - ``C-c``: copy highlighted text to clipboard (prompts are automatically stripped).
 - ``C-S-c``: copy highlighted text to clipboard (prompts are not stripped).
 - ``C-v``: paste text from clipboard.
 - ``C-z``: undo (retrieves lost text if you move out of a cell with the arrows).
 - ``C-S-z``: redo.
 - ``C-o``: move to 'other' area, between pager and terminal.
 - ``C-l``: clear terminal.
 - ``C-a``: go to beginning of line.
 - ``C-e``: go to end of line.
 - ``C-u``: kill from cursor to the begining of the line.
 - ``C-k``: kill from cursor to the end of the line.
 - ``C-y``: yank (paste)
 - ``C-p``: previous line (like up arrow)
 - ``C-n``: next line (like down arrow)
 - ``C-f``: forward (like right arrow)
 - ``C-b``: back (like left arrow)
 - ``C-d``: delete next character, or exits if input is empty
 - ``M-<``: move to the beginning of the input region.
 - ``M->``: move to the end of the input region.
 - ``M-d``: delete next word.
 - ``M-Backspace``: delete previous word.
 - ``C-.``: force a kernel restart (a confirmation dialog appears).
 - ``C-+``: increase font size.
 - ``C--``: decrease font size.
 - ``C-M-Space``: toggle full screen. (Command-Control-Space on Mac OS X)
 
 The IPython pager
 =================
 
 IPython will show long blocks of text from many sources using a builtin pager.
 You can control where this pager appears with the ``--paging`` command-line
 flag:
 
 - ``inside`` [default]: the pager is overlaid on top of the main terminal. You
   must quit the pager to get back to the terminal (similar to how a pager such
   as ``less`` or ``more`` works).
 
 - ``vsplit``: the console is made double-tall, and the pager appears on the
   bottom area when needed.  You can view its contents while using the terminal.
 
 - ``hsplit``: the console is made double-wide, and the pager appears on the
   right area when needed.  You can view its contents while using the terminal.
 
 - ``none``: the console never pages output.
 
 If you use the vertical or horizontal paging modes, you can navigate between
 terminal and pager as follows:
 
 - Tab key: goes from pager to terminal (but not the other way around).
 - Control-o: goes from one to another always.
 - Mouse: click on either.
 
 In all cases, the ``q`` or ``Escape`` keys quit the pager (when used with the
 focus on the pager area).
 
 Running subprocesses
 ====================
 
 The graphical IPython console uses the ``pexpect`` module to run subprocesses
 when you type ``!command``.  This has a number of advantages (true asynchronous
 output from subprocesses as well as very robust termination of rogue
 subprocesses with ``Control-C``), as well as some limitations.  The main
 limitation is that you can *not* interact back with the subprocess, so anything
 that invokes a pager or expects you to type input into it will block and hang
 (you can kill it with ``Control-C``).
 
 We have provided as magics ``%less`` to page files (aliased to ``%more``),
 ``%clear`` to clear the terminal, and ``%man`` on Linux/OSX.  These cover the
 most common commands you'd want to call in your subshell and that would cause
 problems if invoked via ``!cmd``, but you need to be aware of this limitation.
 
 Display
 =======
 
 The IPython console can now display objects in a variety of formats, including
 HTML, PNG and SVG. This is accomplished using the display functions in
 ``IPython.core.display``::
 
     In [4]: from IPython.core.display import display, display_html
 
     In [5]: from IPython.core.display import display_png, display_svg
 
 Python objects can simply be passed to these functions and the appropriate
 representations will be displayed in the console as long as the objects know
 how to compute those representations. The easiest way of teaching objects how
 to format themselves in various representations is to define special methods
 such as: ``_repr_html_``, ``_repr_svg_`` and ``_repr_png_``. IPython's display formatters
 can also be given custom formatter functions for various types::
 
     In [6]: ip = get_ipython()
 
     In [7]: html_formatter = ip.display_formatter.formatters['text/html']
 
     In [8]: html_formatter.for_type(Foo, foo_to_html)
 
 For further details, see ``IPython.core.formatters``.
 
 Inline matplotlib graphics
 ==========================
 
 The IPython console is capable of displaying matplotlib figures inline, in SVG
 or PNG format.  If started with the ``matplotlib=inline``, then all figures are
 rendered inline automatically (PNG by default).  If started with ``--matplotlib``
 or ``matplotlib=<your backend>``, then a GUI backend will be used, but IPython's
 ``display()`` and ``getfigs()`` functions can be used to view plots inline::
 
     In [9]: display(*getfigs())    # display all figures inline
 
     In[10]: display(*getfigs(1,2)) # display figures 1 and 2 inline
 """
 
 
 quick_guide = """\
 ?         -> Introduction and overview of IPython's features.
 %quickref -> Quick reference.
 help      -> Python's own help system.
 object?   -> Details about 'object', use 'object??' for extra details.
 """
 
 gui_note = """\
 %guiref   -> A brief reference about the graphical user interface.
 """
 
 default_banner_parts = [
     'Python %s\n' % (sys.version.split('\n')[0],),
     'Type "copyright", "credits" or "license" for more information.\n\n',
     'IPython {version} -- An enhanced Interactive Python.\n'.format(
         version=release.version,
         ),
     quick_guide
 ]
 
 default_gui_banner_parts = default_banner_parts + [gui_note]
 
 default_banner = ''.join(default_banner_parts)
 
 default_gui_banner = ''.join(default_gui_banner_parts)
 
 # page GUI Reference, for use as a magic:
 
 def page_guiref(arg_s=None):
     """Show a basic reference about the GUI Console."""
     from IPython.core import page
     page.page(gui_reference, auto_html=True)
 

docs/man/ipython.1

@@ -1,61 +1,60 b''
 .\"                                      Hey, EMACS: -*- nroff -*-
 .\" First parameter, NAME, should be all caps
 .\" Second parameter, SECTION, should be 1-8, maybe w/ subsection
 .\" other parameters are allowed: see man(7), man(1)
 .TH IPYTHON 1 "July 15, 2011"
 .\" Please adjust this date whenever revising the manpage.
 .\"
 .\" Some roff macros, for reference:
 .\" .nh        disable hyphenation
 .\" .hy        enable hyphenation
 .\" .ad l      left justify
 .\" .ad b      justify to both left and right margins
 .\" .nf        disable filling
 .\" .fi        enable filling
 .\" .br        insert line break
 .\" .sp <n>    insert n+1 empty lines
 .\" for manpage-specific macros, see man(7) and groff_man(7)
 .\" .SH        section heading
 .\" .SS        secondary section heading
 .\"
 .\"
 .\" To preview this page as plain text: nroff -man ipython.1
 .\"
 .SH NAME
 ipython \- Tools for Interactive Computing in Python.
 .SH SYNOPSIS
 .B ipython
 .RI [ options ] " files" ...
 
 .B ipython subcommand
 .RI [ options ] ...
 
 .SH DESCRIPTION
 An interactive Python shell with automatic history (input and output), dynamic
 object introspection, easier configuration, command completion, access to the
 system shell, integration with numerical and scientific computing tools,
 web notebook, Qt console, and more.
 
 For more information on how to use IPython, see 'ipython \-\-help',
 or 'ipython \-\-help\-all' for all available command\(hyline options.
 
 .SH "ENVIRONMENT VARIABLES"
 .sp
 .PP
 \fIIPYTHONDIR\fR
 .RS 4
 This is the location where IPython stores all its configuration files.  The default
-on most platforms is $HOME/.ipython, but on Linux IPython respects the XDG config
-specification, which will put IPYTHONDIR in $HOME/.config/ipython by default.
+is $HOME/.ipython if IPYTHONDIR is not defined.
 
 You can see the computed value of IPYTHONDIR with `ipython locate`.
 
 .SH FILES
 
 IPython uses various configuration files stored in profiles within IPYTHONDIR.
 To generate the default configuration files and start configuring IPython,
 do 'ipython profile create', and edit '*_config.py' files located in
 IPYTHONDIR/profile_default.
 
 .SH AUTHORS
 IPython is written by the IPython Development Team <https://github.com/ipython/ipython>.

docs/source/config/old.rst

@@ -1,231 +1,230 b''
 .. _initial config:
 
 =============================================================
 Outdated configuration information that might still be useful
 =============================================================
 
 .. warning::
 
     All of the information in this file is outdated. Until the new
     configuration system is better documented, this material is being kept.
 
 This section will help you set various things in your environment for
 your IPython sessions to be as efficient as possible. All of IPython's
 configuration information, along with several example files, is stored
-in a directory named by default $HOME/.config/ipython if $HOME/.config 
-exists (Linux), or $HOME/.ipython as a secondary default. You can change this by
+in a directory named by default $HOME/.ipython. You can change this by
 defining the environment variable IPYTHONDIR, or at runtime with the
 command line option -ipythondir.
 
 If all goes well, the first time you run IPython it should automatically create
 a user copy of the config directory for you, based on its builtin defaults. You
 can look at the files it creates to learn more about configuring the
 system. The main file you will modify to configure IPython's behavior is called
 ipythonrc (with a .ini extension under Windows), included for reference
 :ref:`here <ipythonrc>`. This file is very commented and has many variables you
 can change to suit your taste, you can find more details :ref:`here
 <customization>`. Here we discuss the basic things you will want to make sure
 things are working properly from the beginning.
 
 Color
 =====
 
 The default IPython configuration has most bells and whistles turned on
 (they're pretty safe). But there's one that may cause problems on some
 systems: the use of color on screen for displaying information. This is
 very useful, since IPython can show prompts and exception tracebacks
 with various colors, display syntax-highlighted source code, and in
 general make it easier to visually parse information.
 
 The following terminals seem to handle the color sequences fine:
 
     * Linux main text console, KDE Konsole, Gnome Terminal, E-term,
       rxvt, xterm.
     * CDE terminal (tested under Solaris). This one boldfaces light colors.
     * (X)Emacs buffers. See the emacs_ section for more details on
       using IPython with (X)Emacs.
     * A Windows (XP/2k) command prompt with pyreadline_.
     * A Windows (XP/2k) CygWin shell. Although some users have reported
       problems; it is not clear whether there is an issue for everyone
       or only under specific configurations. If you have full color
       support under cygwin, please post to the IPython mailing list so
       this issue can be resolved for all users.
 
 .. _pyreadline: https://code.launchpad.net/pyreadline
       
 These have shown problems:
 
     * Windows command prompt in WinXP/2k logged into a Linux machine via
       telnet or ssh.
     * Windows native command prompt in WinXP/2k, without Gary Bishop's
       extensions. Once Gary's readline library is installed, the normal
       WinXP/2k command prompt works perfectly.
 
 Currently the following color schemes are available:
 
     * NoColor: uses no color escapes at all (all escapes are empty '' ''
       strings). This 'scheme' is thus fully safe to use in any terminal.
     * Linux: works well in Linux console type environments: dark
       background with light fonts. It uses bright colors for
       information, so it is difficult to read if you have a light
       colored background.
     * LightBG: the basic colors are similar to those in the Linux scheme
       but darker. It is easy to read in terminals with light backgrounds.
 
 IPython uses colors for two main groups of things: prompts and
 tracebacks which are directly printed to the terminal, and the object
 introspection system which passes large sets of data through a pager.
 
 Input/Output prompts and exception tracebacks
 =============================================
 
 You can test whether the colored prompts and tracebacks work on your
 system interactively by typing '%colors Linux' at the prompt (use
 '%colors LightBG' if your terminal has a light background). If the input
 prompt shows garbage like::
 
     [0;32mIn [[1;32m1[0;32m]: [0;00m
 
 instead of (in color) something like::
 
     In [1]:
 
 this means that your terminal doesn't properly handle color escape
 sequences. You can go to a 'no color' mode by typing '%colors NoColor'.
 
 You can try using a different terminal emulator program (Emacs users,
 see below). To permanently set your color preferences, edit the file
 $IPYTHONDIR/ipythonrc and set the colors option to the desired value.
 
 
 Object details (types, docstrings, source code, etc.)
 =====================================================
 
 IPython has a set of special functions for studying the objects you are working
 with, discussed in detail :ref:`here <dynamic_object_info>`. But this system
 relies on passing information which is longer than your screen through a data
 pager, such as the common Unix less and more programs. In order to be able to
 see this information in color, your pager needs to be properly configured. I
 strongly recommend using less instead of more, as it seems that more simply can
 not understand colored text correctly.
 
 In order to configure less as your default pager, do the following:
 
    1. Set the environment PAGER variable to less.
    2. Set the environment LESS variable to -r (plus any other options
       you always want to pass to less by default). This tells less to
       properly interpret control sequences, which is how color
       information is given to your terminal.
 
 For the bash shell, add to your ~/.bashrc file the lines::
 
     export PAGER=less
     export LESS=-r
 
 For the csh or tcsh shells, add to your ~/.cshrc file the lines::
 
     setenv PAGER less
     setenv LESS -r
     
 There is similar syntax for other Unix shells, look at your system
 documentation for details.
 
 If you are on a system which lacks proper data pagers (such as Windows),
 IPython will use a very limited builtin pager.
 
 .. _Prompts:
 
 Fine-tuning your prompt
 =======================
 
 IPython's prompts can be customized using a syntax similar to that of
 the bash shell. Many of bash's escapes are supported, as well as a few
 additional ones. We list them below::
 
     \#
         the prompt/history count number. This escape is automatically
         wrapped in the coloring codes for the currently active color scheme. 
     \N
         the 'naked' prompt/history count number: this is just the number
         itself, without any coloring applied to it. This lets you produce
         numbered prompts with your own colors. 
     \D
         the prompt/history count, with the actual digits replaced by dots.
         Used mainly in continuation prompts (prompt_in2) 
     \w
         the current working directory 
     \W
         the basename of current working directory 
     \Xn
         where $n=0\ldots5.$ The current working directory, with $HOME
         replaced by ~, and filtered out to contain only $n$ path elements 
     \Yn
         Similar to \Xn, but with the $n+1$ element included if it is ~ (this
         is similar to the behavior of the %cn escapes in tcsh) 
     \u
         the username of the current user 
     \$
         if the effective UID is 0, a #, otherwise a $ 
     \h
         the hostname up to the first '.' 
     \H
         the hostname 
     \n
         a newline 
     \r
         a carriage return 
     \v
         IPython version string 
 
 In addition to these, ANSI color escapes can be insterted into the
 prompts, as \C_ColorName. The list of valid color names is: Black, Blue,
 Brown, Cyan, DarkGray, Green, LightBlue, LightCyan, LightGray,
 LightGreen, LightPurple, LightRed, NoColor, Normal, Purple, Red, White,
 Yellow.
 
 Finally, IPython supports the evaluation of arbitrary expressions in
 your prompt string. The prompt strings are evaluated through the syntax
 of PEP 215, but basically you can use $x.y to expand the value of x.y,
 and for more complicated expressions you can use braces: ${foo()+x} will
 call function foo and add to it the value of x, before putting the
 result into your prompt. For example, using
 prompt_in1 '${commands.getoutput("uptime")}\nIn [\#]: ' 
 will print the result of the uptime command on each prompt (assuming the
 commands module has been imported in your ipythonrc file).
 
 
       Prompt examples
 
 The following options in an ipythonrc file will give you IPython's
 default prompts::
 
     prompt_in1 'In [\#]:' 
     prompt_in2 '   .\D.:' 
     prompt_out 'Out[\#]:'
 
 which look like this::
 
     In [1]: 1+2 
     Out[1]: 3
 
     In [2]: for i in (1,2,3): 
        ...:    print i, 
        ...: 
     1 2 3
 
 These will give you a very colorful prompt with path information::
 
     #prompt_in1 '\C_Red\u\C_Blue[\C_Cyan\Y1\C_Blue]\C_LightGreen\#>' 
     prompt_in2 ' ..\D>' 
     prompt_out '<\#>'
 
 which look like this::
 
     fperez[~/ipython]1> 1+2 
                     <1> 3 
     fperez[~/ipython]2> for i in (1,2,3): 
                    ...>     print i, 
                    ...> 
     1 2 3
 
 

docs/source/config/overview.rst

@@ -1,531 +1,529 b''
 .. _config_overview:
 
 ============================================
 Overview of the IPython configuration system
 ============================================
 
 This section describes the IPython configuration system. 
 
 The following discussion is for users who want to configure
 IPython to their liking.  Developers who want to know how they can
 enable their objects to take advantage of the configuration system
 should consult the :ref:`developer guide <developer_guide>`
 
 The main concepts
 =================
 
 There are a number of abstractions that the IPython configuration system uses.
 Each of these abstractions is represented by a Python class.
 
 Configuration object: :class:`~IPython.config.loader.Config`
     A configuration object is a simple dictionary-like class that holds
     configuration attributes and sub-configuration objects. These classes
     support dotted attribute style access (``Foo.bar``) in addition to the
     regular dictionary style access (``Foo['bar']``). Configuration objects
     are smart. They know how to merge themselves with other configuration
     objects and they automatically create sub-configuration objects.
 
 Application: :class:`~IPython.config.application.Application`
     An application is a process that does a specific job. The most obvious
     application is the :command:`ipython` command line program. Each
     application reads *one or more* configuration files and a single set of
     command line options
     and then produces a master configuration object for the application. This
     configuration object is then passed to the configurable objects that the
     application creates. These configurable objects implement the actual logic
     of the application and know how to configure themselves given the
     configuration object.
     
     Applications always have a `log` attribute that is a configured Logger.
     This allows centralized logging configuration per-application.
 
 Configurable: :class:`~IPython.config.configurable.Configurable`
     A configurable is a regular Python class that serves as a base class for
     all main classes in an application. The
     :class:`~IPython.config.configurable.Configurable` base class is
     lightweight and only does one things.
 
     This :class:`~IPython.config.configurable.Configurable` is a subclass
     of :class:`~IPython.utils.traitlets.HasTraits` that knows how to configure
     itself. Class level traits with the metadata ``config=True`` become
     values that can be configured from the command line and configuration
     files.
     
     Developers create :class:`~IPython.config.configurable.Configurable`
     subclasses that implement all of the logic in the application. Each of
     these subclasses has its own configuration information that controls how
     instances are created.
 
 Singletons: :class:`~IPython.config.configurable.SingletonConfigurable`
     Any object for which there is a single canonical instance. These are
     just like Configurables, except they have a class method 
     :meth:`~IPython.config.configurable.SingletonConfigurable.instance`,
     that returns the current active instance (or creates one if it
     does not exist).  Examples of singletons include
     :class:`~IPython.config.application.Application`s and
     :class:`~IPython.core.interactiveshell.InteractiveShell`.  This lets
     objects easily connect to the current running Application without passing
     objects around everywhere.  For instance, to get the current running 
     Application instance, simply do: ``app = Application.instance()``.
 
 
 .. note::
 
     Singletons are not strictly enforced - you can have many instances
     of a given singleton class, but the :meth:`instance` method will always
     return the same one.
 
 Having described these main concepts, we can now state the main idea in our
 configuration system: *"configuration" allows the default values of class
 attributes to be controlled on a class by class basis*. Thus all instances of
 a given class are configured in the same way. Furthermore, if two instances
 need to be configured differently, they need to be instances of two different
 classes. While this model may seem a bit restrictive, we have found that it
 expresses most things that need to be configured extremely well. However, it
 is possible to create two instances of the same class that have different
 trait values. This is done by overriding the configuration.
 
 Now, we show what our configuration objects and files look like.
 
 Configuration objects and files
 ===============================
 
 A configuration file is simply a pure Python file that sets the attributes
 of a global, pre-created configuration object.  This configuration object is a 
 :class:`~IPython.config.loader.Config` instance.  While in a configuration
 file, to get a reference to this object, simply call the :func:`get_config`
 function.  We inject this function into the global namespace that the 
 configuration file is executed in.
 
 Here is an example of a super simple configuration file that does nothing::
 
     c = get_config()
 
 Once you get a reference to the configuration object, you simply set
 attributes on it.  All you have to know is:
 
 * The name of each attribute.
 * The type of each attribute.
 
 The answers to these two questions are provided by the various
 :class:`~IPython.config.configurable.Configurable` subclasses that an
 application uses. Let's look at how this would work for a simple configurable
 subclass::
 
     # Sample configurable:
     from IPython.config.configurable import Configurable
     from IPython.utils.traitlets import Int, Float, Unicode, Bool
     
     class MyClass(Configurable):
         name = Unicode(u'defaultname', config=True)
         ranking = Int(0, config=True)
         value = Float(99.0)
         # The rest of the class implementation would go here..
 
 In this example, we see that :class:`MyClass` has three attributes, two
 of whom (``name``, ``ranking``) can be configured.  All of the attributes
 are given types and default values.  If a :class:`MyClass` is instantiated,
 but not configured, these default values will be used.  But let's see how
 to configure this class in a configuration file::
 
     # Sample config file
     c = get_config()
     
     c.MyClass.name = 'coolname'
     c.MyClass.ranking = 10
 
 After this configuration file is loaded, the values set in it will override
 the class defaults anytime a :class:`MyClass` is created.  Furthermore,
 these attributes will be type checked and validated anytime they are set.
 This type checking is handled by the :mod:`IPython.utils.traitlets` module,
 which provides the :class:`Unicode`, :class:`Int` and :class:`Float` types.
 In addition to these traitlets, the :mod:`IPython.utils.traitlets` provides
 traitlets for a number of other types.
 
 .. note::
 
     Underneath the hood, the :class:`Configurable` base class is a subclass of
     :class:`IPython.utils.traitlets.HasTraits`. The
     :mod:`IPython.utils.traitlets` module is a lightweight version of
     :mod:`enthought.traits`. Our implementation is a pure Python subset
     (mostly API compatible) of :mod:`enthought.traits` that does not have any
     of the automatic GUI generation capabilities. Our plan is to achieve 100%
     API compatibility to enable the actual :mod:`enthought.traits` to
     eventually be used instead. Currently, we cannot use
     :mod:`enthought.traits` as we are committed to the core of IPython being
     pure Python.
 
 It should be very clear at this point what the naming convention is for 
 configuration attributes::
 
     c.ClassName.attribute_name = attribute_value
 
 Here, ``ClassName`` is the name of the class whose configuration attribute you
 want to set, ``attribute_name`` is the name of the attribute you want to set
 and ``attribute_value`` the the value you want it to have. The ``ClassName``
 attribute of ``c`` is not the actual class, but instead is another
 :class:`~IPython.config.loader.Config` instance.
 
 .. note::
 
     The careful reader may wonder how the ``ClassName`` (``MyClass`` in
     the above example) attribute of the configuration object ``c`` gets
     created. These attributes are created on the fly by the
     :class:`~IPython.config.loader.Config` instance, using a simple naming
     convention. Any attribute of a :class:`~IPython.config.loader.Config`
     instance whose name begins with an uppercase character is assumed to be a
     sub-configuration and a new empty :class:`~IPython.config.loader.Config`
     instance is dynamically created for that attribute. This allows deeply
     hierarchical information created easily (``c.Foo.Bar.value``) on the fly.
 
 Configuration files inheritance
 ===============================
 
 Let's say you want to have different configuration files for various purposes.
 Our configuration system makes it easy for one configuration file to inherit
 the information in another configuration file. The :func:`load_subconfig`
 command can be used in a configuration file for this purpose. Here is a simple
 example that loads all of the values from the file :file:`base_config.py`::
 
     # base_config.py
     c = get_config()
     c.MyClass.name = 'coolname'
     c.MyClass.ranking = 100
 
 into the configuration file :file:`main_config.py`::
 
     # main_config.py
     c = get_config()
     
     # Load everything from base_config.py
     load_subconfig('base_config.py')
     
     # Now override one of the values
     c.MyClass.name = 'bettername'
 
 In a situation like this the :func:`load_subconfig` makes sure that the
 search path for sub-configuration files is inherited from that of the parent.
 Thus, you can typically put the two in the same directory and everything will
 just work.
 
 You can also load configuration files by profile, for instance:
 
 .. sourcecode:: python
 
     load_subconfig('ipython_config.py', profile='default')
 
 to inherit your default configuration as a starting point.
 
 
 Class based configuration inheritance
 =====================================
 
 There is another aspect of configuration where inheritance comes into play.
 Sometimes, your classes will have an inheritance hierarchy that you want
 to be reflected in the configuration system.  Here is a simple example::
 
     from IPython.config.configurable import Configurable
     from IPython.utils.traitlets import Int, Float, Unicode, Bool
     
     class Foo(Configurable):
         name = Unicode(u'fooname', config=True)
         value = Float(100.0, config=True)
     
     class Bar(Foo):
         name = Unicode(u'barname', config=True)
         othervalue = Int(0, config=True)
 
 Now, we can create a configuration file to configure instances of :class:`Foo`
 and :class:`Bar`::
 
     # config file
     c = get_config()
     
     c.Foo.name = u'bestname'
     c.Bar.othervalue = 10
 
 This class hierarchy and configuration file accomplishes the following:
 
 * The default value for :attr:`Foo.name` and :attr:`Bar.name` will be
   'bestname'.  Because :class:`Bar` is a :class:`Foo` subclass it also
   picks up the configuration information for :class:`Foo`.
 * The default value for :attr:`Foo.value` and :attr:`Bar.value` will be
   ``100.0``, which is the value specified as the class default.
 * The default value for :attr:`Bar.othervalue` will be 10 as set in the
   configuration file.  Because :class:`Foo` is the parent of :class:`Bar`
   it doesn't know anything about the :attr:`othervalue` attribute.
 
 
 .. _ipython_dir:
 
 Configuration file location
 ===========================
 
 So where should you put your configuration files? IPython uses "profiles" for
 configuration, and by default, all profiles will be stored in the so called
 "IPython directory". The location of this directory is determined by the
 following algorithm:
 
 * If the ``ipython-dir`` command line flag is given, its value is used.
 
 * If not, the value returned by :func:`IPython.utils.path.get_ipython_dir`
   is used. This function will first look at the :envvar:`IPYTHONDIR`
   environment variable and then default to :file:`~/.ipython`.
   Historical support for the :envvar:`IPYTHON_DIR` environment variable will
   be removed in a future release.
 
 For most users, the configuration directory will be :file:`~/.ipython`.
 
 Previous versions of IPython on Linux would use the XDG config directory,
 creating :file:`~/.config/ipython` by default. We have decided to go
 back to :file:`~/.ipython` for consistency among systems. IPython will
 issue a warning if it finds the XDG location, and will move it to the new
 location if there isn't already a directory there.
 
 Once the location of the IPython directory has been determined, you need to know
 which profile you are using. For users with a single configuration, this will
 simply be 'default', and will be located in 
 :file:`<IPYTHONDIR>/profile_default`.
 
 The next thing you need to know is what to call your configuration file. The
 basic idea is that each application has its own default configuration filename.
 The default named used by the :command:`ipython` command line program is
 :file:`ipython_config.py`, and *all* IPython applications will use this file.
 Other applications, such as the parallel :command:`ipcluster` scripts or the
 QtConsole will load their own config files *after* :file:`ipython_config.py`. To
 load a particular configuration file instead of the default, the name can be
 overridden by the ``config_file`` command line flag.
 
 To generate the default configuration files, do::
 
     $ ipython profile create
 
 and you will have a default :file:`ipython_config.py` in your IPython directory
 under :file:`profile_default`. If you want the default config files for the
 :mod:`IPython.parallel` applications, add ``--parallel`` to the end of the
 command-line args.
 
 
 Locating these files
 --------------------
 
 From the command-line, you can quickly locate the IPYTHONDIR or a specific
 profile with:
 
 .. sourcecode:: bash
 
     $ ipython locate
     /home/you/.ipython
     
     $ ipython locate profile foo
     /home/you/.ipython/profile_foo
 
 These map to the utility functions: :func:`IPython.utils.path.get_ipython_dir`
 and :func:`IPython.utils.path.locate_profile` respectively.
 
 
 .. _Profiles:
 
 Profiles
 ========
 
 A profile is a directory containing configuration and runtime files, such as
 logs, connection info for the parallel apps, and your IPython command history.
 
 The idea is that users often want to maintain a set of configuration files for
 different purposes: one for doing numerical computing with NumPy and SciPy and
 another for doing symbolic computing with SymPy. Profiles make it easy to keep a
 separate configuration files, logs, and histories for each of these purposes.
 
 Let's start by showing how a profile is used:
 
 .. code-block:: bash
 
     $ ipython --profile=sympy
 
 This tells the :command:`ipython` command line program to get its configuration
 from the "sympy" profile. The file names for various profiles do not change. The
 only difference is that profiles are named in a special way. In the case above,
 the "sympy" profile means looking for :file:`ipython_config.py` in :file:`<IPYTHONDIR>/profile_sympy`.
 
 The general pattern is this: simply create a new profile with:
 
 .. code-block:: bash
 
     $ ipython profile create <name>
 
 which adds a directory called ``profile_<name>`` to your IPython directory. Then
 you can load this profile by adding ``--profile=<name>`` to your command line
 options. Profiles are supported by all IPython applications.
 
 IPython ships with some sample profiles in :file:`IPython/config/profile`. If
 you create profiles with the name of one of our shipped profiles, these config
 files will be copied over instead of starting with the automatically generated
 config files.
 
 Security Files
 --------------
 
 If you are using the notebook, qtconsole, or parallel code, IPython stores
 connection information in small JSON files in the active profile's security
 directory. This directory is made private, so only you can see the files inside. If
 you need to move connection files around to other computers, this is where they will
 be. If you want your code to be able to open security files by name, we have a
 convenience function :func:`IPython.utils.path.get_security_file`, which will return
 the absolute path to a security file from its filename and [optionally] profile
 name.
 
 .. _startup_files:
 
 Startup Files
 -------------
 
 If you want some code to be run at the beginning of every IPython session with
 a particular profile, the easiest way is to add Python (``.py``) or 
 IPython (``.ipy``) scripts to your :file:`<profile>/startup` directory. Files
 in this directory will always be executed as soon as the IPython shell is 
 constructed, and before any other code or scripts you have specified. If you 
 have multiple files in the startup directory, they will be run in 
 lexicographical order, so you can control the ordering by adding a '00-' 
 prefix.
 
 
 .. _commandline:
 
 Command-line arguments
 ======================
 
 IPython exposes *all* configurable options on the command-line. The command-line
 arguments are generated from the Configurable traits of the classes associated
 with a given Application.  Configuring IPython from the command-line may look
 very similar to an IPython config file
 
 IPython applications use a parser called
 :class:`~IPython.config.loader.KeyValueLoader` to load values into a Config
 object.  Values are assigned in much the same way as in a config file:
 
 .. code-block:: bash
 
     $ ipython --InteractiveShell.use_readline=False --BaseIPythonApplication.profile='myprofile'
 
 Is the same as adding:
 
 .. sourcecode:: python
 
     c.InteractiveShell.use_readline=False
     c.BaseIPythonApplication.profile='myprofile'
 
 to your config file. Key/Value arguments *always* take a value, separated by '='
 and no spaces.
 
 Common Arguments
 ----------------
 
 Since the strictness and verbosity of the KVLoader above are not ideal for everyday
 use, common arguments can be specified as flags_ or aliases_.
 
 Flags and Aliases are handled by :mod:`argparse` instead, allowing for more flexible
 parsing. In general, flags and aliases are prefixed by ``--``, except for those
 that are single characters, in which case they can be specified with a single ``-``, e.g.:
 
 .. code-block:: bash
 
     $ ipython -i -c "import numpy; x=numpy.linspace(0,1)" --profile testing --colors=lightbg
 
 Aliases
 *******
 
 For convenience, applications have a mapping of commonly used traits, so you don't have
 to specify the whole class name:
 
 .. code-block:: bash
 
     $ ipython --profile myprofile
     # and
     $ ipython --profile='myprofile'
     # are equivalent to
     $ ipython --BaseIPythonApplication.profile='myprofile'
 
 Flags
 *****
 
 Applications can also be passed **flags**. Flags are options that take no
 arguments. They are simply wrappers for
 setting one or more configurables with predefined values, often True/False.
 
 For instance:
 
 .. code-block:: bash
 
     $ ipcontroller --debug
     # is equivalent to
     $ ipcontroller --Application.log_level=DEBUG
     # and
     $ ipython --matploitlib
     # is equivalent to
     $ ipython --matplotlib auto
     # or
     $ ipython --no-banner
     # is equivalent to
     $ ipython --TerminalIPythonApp.display_banner=False
 
 Subcommands
 -----------
 
 
 Some IPython applications have **subcommands**. Subcommands are modeled after
 :command:`git`, and are called with the form :command:`command subcommand
 [...args]`.  Currently, the QtConsole is a subcommand of terminal IPython:
 
 .. code-block:: bash
 
     $ ipython qtconsole --profile myprofile
 
 and :command:`ipcluster` is simply a wrapper for its various subcommands (start,
 stop, engines).
 
 .. code-block:: bash
 
     $ ipcluster start --profile=myprofile -n 4
 
 
 To see a list of the available aliases, flags, and subcommands for an IPython application, simply pass ``-h`` or ``--help``.  And to see the full list of configurable options (*very* long), pass ``--help-all``.
 
 
 Design requirements
 ===================
 
 Here are the main requirements we wanted our configuration system to have:
 
 * Support for hierarchical configuration information.
 
 * Full integration with command line option parsers.  Often, you want to read
   a configuration file, but then override some of the values with command line
   options.  Our configuration system automates this process and allows each
   command line option to be linked to a particular attribute in the 
   configuration hierarchy that it will override.
 
 * Configuration files that are themselves valid Python code. This accomplishes
   many things. First, it becomes possible to put logic in your configuration
   files that sets attributes based on your operating system, network setup,
   Python version, etc. Second, Python has a super simple syntax for accessing
   hierarchical data structures, namely regular attribute access
   (``Foo.Bar.Bam.name``). Third, using Python makes it easy for users to
   import configuration attributes from one configuration file to another.
   Fourth, even though Python is dynamically typed, it does have types that can
   be checked at runtime. Thus, a ``1`` in a config file is the integer '1',
   while a ``'1'`` is a string.
 
 * A fully automated method for getting the configuration information to the
   classes that need it at runtime. Writing code that walks a configuration
   hierarchy to extract a particular attribute is painful. When you have
   complex configuration information with hundreds of attributes, this makes
   you want to cry.
 
 * Type checking and validation that doesn't require the entire configuration
   hierarchy to be specified statically before runtime. Python is a very
   dynamic language and you don't always know everything that needs to be
   configured when a program starts.
 
-
-.. _`XDG Base Directory`: http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html