Lib/site.py

   1 """Append module search paths for third-party packages to sys.path.
   2
   3 ****************************************************************
   4 * This module is automatically imported during initialization. *
   5 ****************************************************************
   6
   7 In earlier versions of Python (up to 1.5a3), scripts or modules that
   8 needed to use site-specific modules would place ``import site''
   9 somewhere near the top of their code.  Because of the automatic
  10 import, this is no longer necessary (but code that does it still
  11 works).
  12
  13 This will append site-specific paths to to the module search path.  On
  14 Unix, it starts with sys.prefix and sys.exec_prefix (if different) and
  15 appends lib/python<version>/site-packages as well as lib/site-python.
  16 On other platforms (mainly Mac and Windows), it uses just sys.prefix
  17 (and sys.exec_prefix, if different, but this is unlikely).  The
  18 resulting directories, if they exist, are appended to sys.path, and
  19 also inspected for path configuration files.
  20
  21 A path configuration file is a file whose name has the form
  22 <package>.pth; its contents are additional directories (one per line)
  23 to be added to sys.path.  Non-existing directories (or
  24 non-directories) are never added to sys.path; no directory is added to
  25 sys.path more than once.  Blank lines and lines beginning with
  26 \code{#} are skipped.
  27
  28 For example, suppose sys.prefix and sys.exec_prefix are set to
  29 /usr/local and there is a directory /usr/local/lib/python1.5/site-packages
  30 with three subdirectories, foo, bar and spam, and two path
  31 configuration files, foo.pth and bar.pth.  Assume foo.pth contains the
  32 following:
  33
  34   # foo package configuration
  35   foo
  36   bar
  37   bletch
  38
  39 and bar.pth contains:
  40
  41   # bar package configuration
  42   bar
  43
  44 Then the following directories are added to sys.path, in this order:
  45
  46   /usr/local/lib/python1.5/site-packages/bar
  47   /usr/local/lib/python1.5/site-packages/foo
  48
  49 Note that bletch is omitted because it doesn't exist; bar precedes foo
  50 because bar.pth comes alphabetically before foo.pth; and spam is
  51 omitted because it is not mentioned in either path configuration file.
  52
  53 After these path manipulations, an attempt is made to import a module
  54 named sitecustomize, which can perform arbitrary additional
  55 site-specific customizations.  If this import fails with an
  56 ImportError exception, it is silently ignored.
  57
  58 """
  59
  60 import sys, os
  61
  62 def addsitedir(sitedir):
  63     if sitedir not in sys.path:
  64         sys.path.append(sitedir)        # Add path component
  65     try:
  66         names = os.listdir(sitedir)
  67     except os.error:
  68         return
  69     names = map(os.path.normcase, names)
  70     names.sort()
  71     for name in names:
  72         if name[-4:] == ".pth":
  73             addpackage(sitedir, name)
  74
  75 def addpackage(sitedir, name):
  76     fullname = os.path.join(sitedir, name)
  77     try:
  78         f = open(fullname)
  79     except IOError:
  80         return
  81     while 1:
  82         dir = f.readline()
  83         if not dir:
  84             break
  85         if dir[0] == '#':
  86             continue
  87         if dir[-1] == '\n':
  88             dir = dir[:-1]
  89         dir = os.path.join(sitedir, dir)
  90         if dir not in sys.path and os.path.exists(dir):
  91             sys.path.append(dir)
  92
  93 prefixes = [sys.prefix]
  94 if sys.exec_prefix != sys.prefix:
  95     prefixes.append(sys.exec_prefix)
  96 for prefix in prefixes:
  97     if prefix:
  98         if os.sep == '/':
  99             sitedirs = [os.path.join(prefix,
 100                                      "lib",
 101                                      "python" + sys.version[:3],
 102                                      "site-packages"),
 103                         os.path.join(prefix, "lib", "site-python")]
 104         else:
 105             sitedirs = [prefix]
 106         for sitedir in sitedirs:
 107             if os.path.isdir(sitedir):
 108                 addsitedir(sitedir)
 109
 110 # Define new built-ins 'quit' and 'exit'.
 111 # These are simply strings that display a hint on how to exit.
 112 if os.sep == ':':
 113     exit = 'Use Cmd-Q to quit.'
 114 elif os.sep == '\\':
 115     exit = 'Use Ctrl-Z plus Return to exit.'
 116 else:
 117     exit = 'Use Ctrl-D (i.e. EOF) to exit.'
 118 import __builtin__
 119 __builtin__.quit = __builtin__.exit = exit
 120 del exit
 121
 122 try:
 123     import sitecustomize                # Run arbitrary site specific code
 124 except ImportError:
 125     pass                                # No site customization module
 126
 127 def _test():
 128     print "sys.path = ["
 129     for dir in sys.path:
 130         print "    %s," % `dir`
 131     print "]"
 132
 133 if __name__ == '__main__':
 134     _test()