from __future__ import unicode_literals """Module for interactive demos using IPython. This module implements a few classes for running Python scripts interactively in IPython for demonstrations. With very simple markup (a few tags in comments), you can control points where the script stops executing and returns control to IPython. Provided classes ================ The classes are (see their docstrings for further details): - Demo: pure python demos - IPythonDemo: demos with input to be processed by IPython as if it had been typed interactively (so magics work, as well as any other special syntax you may have added via input prefilters). - LineDemo: single-line version of the Demo class. These demos are executed one line at a time, and require no markup. - IPythonLineDemo: IPython version of the LineDemo class (the demo is executed a line at a time, but processed via IPython). - ClearMixin: mixin to make Demo classes with less visual clutter. It declares an empty marquee and a pre_cmd that clears the screen before each block (see Subclassing below). - ClearDemo, ClearIPDemo: mixin-enabled versions of the Demo and IPythonDemo classes. Subclassing =========== The classes here all include a few methods meant to make customization by subclassing more convenient. Their docstrings below have some more details: - marquee(): generates a marquee to provide visible on-screen markers at each block start and end. - pre_cmd(): run right before the execution of each block. - post_cmd(): run right after the execution of each block. If the block raises an exception, this is NOT called. Operation ========= The file is run in its own empty namespace (though you can pass it a string of arguments as if in a command line environment, and it will see those as sys.argv). But at each stop, the global IPython namespace is updated with the current internal demo namespace, so you can work interactively with the data accumulated so far. By default, each block of code is printed (with syntax highlighting) before executing it and you have to confirm execution. This is intended to show the code to an audience first so you can discuss it, and only proceed with execution once you agree. There are a few tags which allow you to modify this behavior. The supported tags are: # stop Defines block boundaries, the points where IPython stops execution of the file and returns to the interactive prompt. You can optionally mark the stop tag with extra dashes before and after the word 'stop', to help visually distinguish the blocks in a text editor: # --- stop --- # silent Make a block execute silently (and hence automatically). Typically used in cases where you have some boilerplate or initialization code which you need executed but do not want to be seen in the demo. # auto Make a block execute automatically, but still being printed. Useful for simple code which does not warrant discussion, since it avoids the extra manual confirmation. # auto_all This tag can _only_ be in the first block, and if given it overrides the individual auto tags to make the whole demo fully automatic (no block asks for confirmation). It can also be given at creation time (or the attribute set later) to override what's in the file. While _any_ python file can be run as a Demo instance, if there are no stop tags the whole file will run in a single block (no different that calling first %pycat and then %run). The minimal markup to make this useful is to place a set of stop tags; the other tags are only there to let you fine-tune the execution. This is probably best explained with the simple example file below. You can copy this into a file named ex_demo.py, and try running it via: from IPython.demo import Demo d = Demo('ex_demo.py') d() <--- Call the d object (omit the parens if you have autocall set to 2). Each time you call the demo object, it runs the next block. The demo object has a few useful methods for navigation, like again(), edit(), jump(), seek() and back(). It can be reset for a new run via reset() or reloaded from disk (in case you've edited the source) via reload(). See their docstrings below. Note: To make this simpler to explore, a file called "demo-exercizer.py" has been added to the "docs/examples/core" directory. Just cd to this directory in an IPython session, and type:: %run demo-exercizer.py and then follow the directions. Example ======= The following is a very simple example of a valid demo file. #################### EXAMPLE DEMO ############################### '''A simple interactive demo to illustrate the use of IPython's Demo class.''' print 'Hello, welcome to an interactive IPython demo.' # The mark below defines a block boundary, which is a point where IPython will # stop execution and return to the interactive prompt. The dashes are actually # optional and used only as a visual aid to clearly separate blocks while # editing the demo code. # stop x = 1 y = 2 # stop # the mark below makes this block as silent # silent print 'This is a silent block, which gets executed but not printed.' # stop # auto print 'This is an automatic block.' print 'It is executed without asking for confirmation, but printed.' z = x+y print 'z=',x # stop # This is just another normal block. print 'z is now:', z print 'bye!' ################### END EXAMPLE DEMO ############################ """ #***************************************************************************** # Copyright (C) 2005-2006 Fernando Perez. # # Distributed under the terms of the BSD License. The full license is in # the file COPYING, distributed as part of this software. # #***************************************************************************** from __future__ import print_function import os import re import shlex import sys from IPython.utils.PyColorize import Parser from IPython.utils import io from IPython.utils.io import file_read, file_readlines from IPython.utils.text import marquee from IPython.utils import openpy __all__ = ['Demo','IPythonDemo','LineDemo','IPythonLineDemo','DemoError'] class DemoError(Exception): pass def re_mark(mark): return re.compile(r'^\s*#\s+\s+%s\s*$' % mark,re.MULTILINE) class Demo(object): re_stop = re_mark('-*\s?stop\s?-*') re_silent = re_mark('silent') re_auto = re_mark('auto') re_auto_all = re_mark('auto_all') def __init__(self,src,title='',arg_str='',auto_all=None): """Make a new demo object. To run the demo, simply call the object. See the module docstring for full details and an example (you can use IPython.Demo? in IPython to see it). Inputs: - src is either a file, or file-like object, or a string that can be resolved to a filename. Optional inputs: - title: a string to use as the demo name. Of most use when the demo you are making comes from an object that has no filename, or if you want an alternate denotation distinct from the filename. - arg_str(''): a string of arguments, internally converted to a list just like sys.argv, so the demo script can see a similar environment. - auto_all(None): global flag to run all blocks automatically without confirmation. This attribute overrides the block-level tags and applies to the whole demo. It is an attribute of the object, and can be changed at runtime simply by reassigning it to a boolean value. """ if hasattr(src, "read"): # It seems to be a file or a file-like object self.fname = "from a file-like object" if title == '': self.title = "from a file-like object" else: self.title = title else: # Assume it's a string or something that can be converted to one self.fname = src if title == '': (filepath, filename) = os.path.split(src) self.title = filename else: self.title = title self.sys_argv = [src] + shlex.split(arg_str) self.auto_all = auto_all self.src = src # get a few things from ipython. While it's a bit ugly design-wise, # it ensures that things like color scheme and the like are always in # sync with the ipython mode being used. This class is only meant to # be used inside ipython anyways, so it's OK. ip = get_ipython() # this is in builtins whenever IPython is running self.ip_ns = ip.user_ns self.ip_colorize = ip.pycolorize self.ip_showtb = ip.showtraceback self.ip_run_cell = ip.run_cell self.shell = ip # load user data and initialize data structures self.reload() def fload(self): """Load file object.""" # read data and parse into blocks if hasattr(self, 'fobj') and self.fobj is not None: self.fobj.close() if hasattr(self.src, "read"): # It seems to be a file or a file-like object self.fobj = self.src else: # Assume it's a string or something that can be converted to one self.fobj = openpy.open(self.fname) def reload(self): """Reload source from disk and initialize state.""" self.fload() self.src = "".join(openpy.strip_encoding_cookie(self.fobj)) src_b = [b.strip() for b in self.re_stop.split(self.src) if b] self._silent = [bool(self.re_silent.findall(b)) for b in src_b] self._auto = [bool(self.re_auto.findall(b)) for b in src_b] # if auto_all is not given (def. None), we read it from the file if self.auto_all is None: self.auto_all = bool(self.re_auto_all.findall(src_b[0])) else: self.auto_all = bool(self.auto_all) # Clean the sources from all markup so it doesn't get displayed when # running the demo src_blocks = [] auto_strip = lambda s: self.re_auto.sub('',s) for i,b in enumerate(src_b): if self._auto[i]: src_blocks.append(auto_strip(b)) else: src_blocks.append(b) # remove the auto_all marker src_blocks[0] = self.re_auto_all.sub('',src_blocks[0]) self.nblocks = len(src_blocks) self.src_blocks = src_blocks # also build syntax-highlighted source self.src_blocks_colored = map(self.ip_colorize,self.src_blocks) # ensure clean namespace and seek offset self.reset() def reset(self): """Reset the namespace and seek pointer to restart the demo""" self.user_ns = {} self.finished = False self.block_index = 0 def _validate_index(self,index): if index<0 or index>=self.nblocks: raise ValueError('invalid block index %s' % index) def _get_index(self,index): """Get the current block index, validating and checking status. Returns None if the demo is finished""" if index is None: if self.finished: print('Demo finished. Use .reset() if you want to rerun it.', file=io.stdout) return None index = self.block_index else: self._validate_index(index) return index def seek(self,index): """Move the current seek pointer to the given block. You can use negative indices to seek from the end, with identical semantics to those of Python lists.""" if index<0: index = self.nblocks + index self._validate_index(index) self.block_index = index self.finished = False def back(self,num=1): """Move the seek pointer back num blocks (default is 1).""" self.seek(self.block_index-num) def jump(self,num=1): """Jump a given number of blocks relative to the current one. The offset can be positive or negative, defaults to 1.""" self.seek(self.block_index+num) def again(self): """Move the seek pointer back one block and re-execute.""" self.back(1) self() def edit(self,index=None): """Edit a block. If no number is given, use the last block executed. This edits the in-memory copy of the demo, it does NOT modify the original source file. If you want to do that, simply open the file in an editor and use reload() when you make changes to the file. This method is meant to let you change a block during a demonstration for explanatory purposes, without damaging your original script.""" index = self._get_index(index) if index is None: return # decrease the index by one (unless we're at the very beginning), so # that the default demo.edit() call opens up the sblock we've last run if index>0: index -= 1 filename = self.shell.mktempfile(self.src_blocks[index]) self.shell.hooks.editor(filename,1) new_block = file_read(filename) # update the source and colored block self.src_blocks[index] = new_block self.src_blocks_colored[index] = self.ip_colorize(new_block) self.block_index = index # call to run with the newly edited index self() def show(self,index=None): """Show a single block on screen""" index = self._get_index(index) if index is None: return print(self.marquee('<%s> block # %s (%s remaining)' % (self.title,index,self.nblocks-index-1)), file=io.stdout) print((self.src_blocks_colored[index]), file=io.stdout) sys.stdout.flush() def show_all(self): """Show entire demo on screen, block by block""" fname = self.title title = self.title nblocks = self.nblocks silent = self._silent marquee = self.marquee for index,block in enumerate(self.src_blocks_colored): if silent[index]: print(marquee('<%s> SILENT block # %s (%s remaining)' % (title,index,nblocks-index-1)), file=io.stdout) else: print(marquee('<%s> block # %s (%s remaining)' % (title,index,nblocks-index-1)), file=io.stdout) print(block, end=' ', file=io.stdout) sys.stdout.flush() def run_cell(self,source): """Execute a string with one or more lines of code""" exec source in self.user_ns def __call__(self,index=None): """run a block of the demo. If index is given, it should be an integer >=1 and <= nblocks. This means that the calling convention is one off from typical Python lists. The reason for the inconsistency is that the demo always prints 'Block n/N, and N is the total, so it would be very odd to use zero-indexing here.""" index = self._get_index(index) if index is None: return try: marquee = self.marquee next_block = self.src_blocks[index] self.block_index += 1 if self._silent[index]: print(marquee('Executing silent block # %s (%s remaining)' % (index,self.nblocks-index-1)), file=io.stdout) else: self.pre_cmd() self.show(index) if self.auto_all or self._auto[index]: print(marquee('output:'), file=io.stdout) else: print(marquee('Press to quit, to execute...'), end=' ', file=io.stdout) ans = raw_input().strip() if ans: print(marquee('Block NOT executed'), file=io.stdout) return try: save_argv = sys.argv sys.argv = self.sys_argv self.run_cell(next_block) self.post_cmd() finally: sys.argv = save_argv except: self.ip_showtb(filename=self.fname) else: self.ip_ns.update(self.user_ns) if self.block_index == self.nblocks: mq1 = self.marquee('END OF DEMO') if mq1: # avoid spurious print >>io.stdout,s if empty marquees are used print(file=io.stdout) print(mq1, file=io.stdout) print(self.marquee('Use .reset() if you want to rerun it.'), file=io.stdout) self.finished = True # These methods are meant to be overridden by subclasses who may wish to # customize the behavior of of their demos. def marquee(self,txt='',width=78,mark='*'): """Return the input string centered in a 'marquee'.""" return marquee(txt,width,mark) def pre_cmd(self): """Method called before executing each block.""" pass def post_cmd(self): """Method called after executing each block.""" pass class IPythonDemo(Demo): """Class for interactive demos with IPython's input processing applied. This subclasses Demo, but instead of executing each block by the Python interpreter (via exec), it actually calls IPython on it, so that any input filters which may be in place are applied to the input block. If you have an interactive environment which exposes special input processing, you can use this class instead to write demo scripts which operate exactly as if you had typed them interactively. The default Demo class requires the input to be valid, pure Python code. """ def run_cell(self,source): """Execute a string with one or more lines of code""" self.shell.run_cell(source) class LineDemo(Demo): """Demo where each line is executed as a separate block. The input script should be valid Python code. This class doesn't require any markup at all, and it's meant for simple scripts (with no nesting or any kind of indentation) which consist of multiple lines of input to be executed, one at a time, as if they had been typed in the interactive prompt. Note: the input can not have *any* indentation, which means that only single-lines of input are accepted, not even function definitions are valid.""" def reload(self): """Reload source from disk and initialize state.""" # read data and parse into blocks self.fload() lines = self.fobj.readlines() src_b = [l for l in lines if l.strip()] nblocks = len(src_b) self.src = ''.join(lines) self._silent = [False]*nblocks self._auto = [True]*nblocks self.auto_all = True self.nblocks = nblocks self.src_blocks = src_b # also build syntax-highlighted source self.src_blocks_colored = map(self.ip_colorize,self.src_blocks) # ensure clean namespace and seek offset self.reset() class IPythonLineDemo(IPythonDemo,LineDemo): """Variant of the LineDemo class whose input is processed by IPython.""" pass class ClearMixin(object): """Use this mixin to make Demo classes with less visual clutter. Demos using this mixin will clear the screen before every block and use blank marquees. Note that in order for the methods defined here to actually override those of the classes it's mixed with, it must go /first/ in the inheritance tree. For example: class ClearIPDemo(ClearMixin,IPythonDemo): pass will provide an IPythonDemo class with the mixin's features. """ def marquee(self,txt='',width=78,mark='*'): """Blank marquee that returns '' no matter what the input.""" return '' def pre_cmd(self): """Method called before executing each block. This one simply clears the screen.""" from IPython.utils.terminal import term_clear term_clear() class ClearDemo(ClearMixin,Demo): pass class ClearIPDemo(ClearMixin,IPythonDemo): pass