- Small fix to demos to flush stdout on each printed block.

IPython/demo.py

@@ -1,309 +1,311 b''
 """Module for interactive demos using IPython.
 
 This module implements a single class, Demo, 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.
 
 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:
 
 # <demo> --- stop ---
 
   Defines block boundaries, the points where IPython stops execution of the
   file and returns to the interactive prompt.
 
 # <demo> 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.
   
 # <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.
 
 # <demo> 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 on).
 
 Each time you call the demo object, it runs the next block.  The demo object
 has a few useful methods for navigation, like again(), 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.
 
 #################### EXAMPLE DEMO <ex_demo.py> ###############################
 '''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.
 # Note that in actual interactive execution, 
 # <demo> --- stop ---
 
 x = 1
 y = 2
 
 # <demo> --- stop ---
 
 # the mark below makes this block as silent
 # <demo> silent
 
 print 'This is a silent block, which gets executed but not printed.'
 
 # <demo> --- stop ---
 # <demo> auto
 print 'This is an automatic block.'
 print 'It is executed without asking for confirmation, but printed.'
 z = x+y
 
 print 'z=',x
 
 # <demo> --- stop ---
 # This is just another normal block.
 print 'z is now:', z
 
 print 'bye!'
 ################### END EXAMPLE DEMO <ex_demo.py> ############################
 
 WARNING: this module uses Python 2.3 features, so it won't work in 2.2
 environments.
 """
 #*****************************************************************************
 #     Copyright (C) 2005-2006 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 exceptions
 import re
 import sys
 
 from IPython.PyColorize import Parser
 from IPython.genutils import marquee, shlex_split, file_read
 
 __all__ = ['Demo','DemoError']
 
 class DemoError(exceptions.Exception): pass
 
 def re_mark(mark):
     return re.compile(r'^\s*#\s+<demo>\s+%s\s*$' % mark,re.MULTILINE)
 
 class Demo:
 
     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,fname,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:
         
           - fname = filename.
 
         Optional inputs:
 
           - 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.
           """
 
         self.fname    = fname
         self.sys_argv = [fname] + shlex_split(arg_str)
         self.auto_all = auto_all
         
         # 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.
         self.ip_showtb   = __IPYTHON__.showtraceback
         self.ip_ns       = __IPYTHON__.user_ns
         self.ip_colorize = __IPYTHON__.pycolorize
 
         # load user data and initialize data structures
         self.reload()
 
     def reload(self):
         """Reload source from disk and initialize state."""
         # read data and parse into blocks
         self.src     = file_read(self.fname)
         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 seek(self,index):
         """Move the current seek pointer to the given block"""
         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):
         """Jump a given number of blocks relative to the current one."""
         self.seek(self.block_index+num)
 
     def again(self):
         """Move the seek pointer back one block and re-execute."""
         self.back(1)
         self()
 
     def show(self,index=None):
         """Show a single block on screen"""
         if index is None:
             if self.finished:
                 print 'Demo finished.  Use reset() if you want to rerun it.'
                 return
             index = self.block_index
         else:
             self._validate_index(index)
         print marquee('<%s> block # %s (%s remaining)' %
                       (self.fname,index,self.nblocks-index-1))
         print self.src_blocks_colored[index],
+        sys.stdout.flush()
 
     def show_all(self):
         """Show entire demo on screen, block by block"""
 
         fname = self.fname
         nblocks = self.nblocks
         silent = self._silent
         for index,block in enumerate(self.src_blocks_colored):
             if silent[index]:
                 print marquee('<%s> SILENT block # %s (%s remaining)' %
                               (fname,index,nblocks-index-1))
             else:
                 print marquee('<%s> block # %s (%s remaining)' %
                               (fname,index,nblocks-index-1))
             print block,
+        sys.stdout.flush()
             
     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."""
 
         if index is None and self.finished:
             print 'Demo finished.  Use reset() if you want to rerun it.'
             return
         if index is None:
             index = self.block_index
         self._validate_index(index)
         try:
             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))
             else:
                 self.show(index)
                 if self.auto_all or self._auto[index]:
                     print marquee('output')
                 else:
                     print marquee('Press <q> to quit, <Enter> to execute...'),
                     ans = raw_input().strip()
                     if ans:
                         print marquee('Block NOT executed')
                         return
             try:
                 save_argv = sys.argv
                 sys.argv = self.sys_argv
                 exec next_block in self.user_ns
             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:
             print
             print marquee(' END OF DEMO ')
             print marquee('Use reset() if you want to rerun it.')
             self.finished = True