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