Lib/lib-old/codehack.py

   1 # A subroutine for extracting a function name from a code object
   2 # (with cache)
   3
   4 import sys
   5 from stat import *
   6 import string
   7 import os
   8 import linecache
   9
  10 # XXX The functions getcodename() and getfuncname() are now obsolete
  11 # XXX as code and function objects now have a name attribute --
  12 # XXX co.co_name and f.func_name.
  13 # XXX getlineno() is now also obsolete because of the new attribute
  14 # XXX of code objects, co.co_firstlineno.
  15
  16 # Extract the function or class name from a code object.
  17 # This is a bit of a hack, since a code object doesn't contain
  18 # the name directly.  So what do we do:
  19 # - get the filename (which *is* in the code object)
  20 # - look in the code string to find the first SET_LINENO instruction
  21 #   (this must be the first instruction)
  22 # - get the line from the file
  23 # - if the line starts with 'class' or 'def' (after possible whitespace),
  24 #   extract the following identifier
  25 #
  26 # This breaks apart when the function was read from <stdin>
  27 # or constructed by exec(), when the file is not accessible,
  28 # and also when the file has been modified or when a line is
  29 # continued with a backslash before the function or class name.
  30 #
  31 # Because this is a pretty expensive hack, a cache is kept.
  32
  33 SET_LINENO = 127 # The opcode (see "opcode.h" in the Python source)
  34 identchars = string.letters + string.digits + '_' # Identifier characters
  35
  36 _namecache = {} # The cache
  37
  38 def getcodename(co):
  39         try:
  40                 return co.co_name
  41         except AttributeError:
  42                 pass
  43         key = `co` # arbitrary but uniquely identifying string
  44         if _namecache.has_key(key): return _namecache[key]
  45         filename = co.co_filename
  46         code = co.co_code
  47         name = ''
  48         if ord(code[0]) == SET_LINENO:
  49                 lineno = ord(code[1]) | ord(code[2]) << 8
  50                 line = linecache.getline(filename, lineno)
  51                 words = string.split(line)
  52                 if len(words) >= 2 and words[0] in ('def', 'class'):
  53                         name = words[1]
  54                         for i in range(len(name)):
  55                                 if name[i] not in identchars:
  56                                         name = name[:i]
  57                                         break
  58         _namecache[key] = name
  59         return name
  60
  61 # Use the above routine to find a function's name.
  62
  63 def getfuncname(func):
  64         try:
  65                 return func.func_name
  66         except AttributeError:
  67                 pass
  68         return getcodename(func.func_code)
  69
  70 # A part of the above code to extract just the line number from a code object.
  71
  72 def getlineno(co):
  73         try:
  74                 return co.co_firstlineno
  75         except AttributeError:
  76                 pass
  77         code = co.co_code
  78         if ord(code[0]) == SET_LINENO:
  79                 return ord(code[1]) | ord(code[2]) << 8
  80         else:
  81                 return -1