Lib/py_compile.py

   1 """Routine to "compile" a .py file to a .pyc (or .pyo) file.
   2
   3 This module has intimate knowledge of the format of .pyc files.
   4 """
   5
   6 import __builtin__
   7 import imp
   8 import marshal
   9 import os
  10 import sys
  11 import traceback
  12
  13 MAGIC = imp.get_magic()
  14
  15 __all__ = ["compile", "main", "PyCompileError"]
  16
  17
  18 class PyCompileError(Exception):
  19     """Exception raised when an error occurs while attempting to
  20     compile the file.
  21
  22     To raise this exception, use
  23
  24         raise PyCompileError(exc_type,exc_value,file[,msg])
  25
  26     where
  27
  28         exc_type:   exception type to be used in error message
  29                     type name can be accesses as class variable
  30                     'exc_type_name'
  31
  32         exc_value:  exception value to be used in error message
  33                     can be accesses as class variable 'exc_value'
  34
  35         file:       name of file being compiled to be used in error message
  36                     can be accesses as class variable 'file'
  37
  38         msg:        string message to be written as error message
  39                     If no value is given, a default exception message will be given,
  40                     consistent with 'standard' py_compile output.
  41                     message (or default) can be accesses as class variable 'msg'
  42
  43     """
  44
  45     def __init__(self, exc_type, exc_value, file, msg=''):
  46         exc_type_name = exc_type.__name__
  47         if exc_type is SyntaxError:
  48             tbtext = ''.join(traceback.format_exception_only(exc_type, exc_value))
  49             errmsg = tbtext.replace('File "<string>"', 'File "%s"' % file)
  50         else:
  51             errmsg = "Sorry: %s: %s" % (exc_type_name,exc_value)
  52
  53         Exception.__init__(self,msg or errmsg,exc_type_name,exc_value,file)
  54
  55         self.exc_type_name = exc_type_name
  56         self.exc_value = exc_value
  57         self.file = file
  58         self.msg = msg or errmsg
  59
  60     def __str__(self):
  61         return self.msg
  62
  63
  64 # Define an internal helper according to the platform
  65 if os.name == "mac":
  66     import MacOS
  67     def set_creator_type(file):
  68         MacOS.SetCreatorAndType(file, 'Pyth', 'PYC ')
  69 else:
  70     def set_creator_type(file):
  71         pass
  72
  73 def wr_long(f, x):
  74     """Internal; write a 32-bit int to a file in little-endian order."""
  75     f.write(chr( x        & 0xff))
  76     f.write(chr((x >> 8)  & 0xff))
  77     f.write(chr((x >> 16) & 0xff))
  78     f.write(chr((x >> 24) & 0xff))
  79
  80 def compile(file, cfile=None, dfile=None, doraise=False):
  81     """Byte-compile one Python source file to Python bytecode.
  82
  83     Arguments:
  84
  85     file:    source filename
  86     cfile:   target filename; defaults to source with 'c' or 'o' appended
  87              ('c' normally, 'o' in optimizing mode, giving .pyc or .pyo)
  88     dfile:   purported filename; defaults to source (this is the filename
  89              that will show up in error messages)
  90     doraise: flag indicating whether or not an exception should be
  91              raised when a compile error is found. If an exception
  92              occurs and this flag is set to False, a string
  93              indicating the nature of the exception will be printed,
  94              and the function will return to the caller. If an
  95              exception occurs and this flag is set to True, a
  96              PyCompileError exception will be raised.
  97
  98     Note that it isn't necessary to byte-compile Python modules for
  99     execution efficiency -- Python itself byte-compiles a module when
 100     it is loaded, and if it can, writes out the bytecode to the
 101     corresponding .pyc (or .pyo) file.
 102
 103     However, if a Python installation is shared between users, it is a
 104     good idea to byte-compile all modules upon installation, since
 105     other users may not be able to write in the source directories,
 106     and thus they won't be able to write the .pyc/.pyo file, and then
 107     they would be byte-compiling every module each time it is loaded.
 108     This can slow down program start-up considerably.
 109
 110     See compileall.py for a script/module that uses this module to
 111     byte-compile all installed files (or all files in selected
 112     directories).
 113
 114     """
 115     f = open(file, 'U')
 116     try:
 117         timestamp = long(os.fstat(f.fileno()).st_mtime)
 118     except AttributeError:
 119         timestamp = long(os.stat(file).st_mtime)
 120     codestring = f.read()
 121     f.close()
 122     if codestring and codestring[-1] != '\n':
 123         codestring = codestring + '\n'
 124     try:
 125         codeobject = __builtin__.compile(codestring, dfile or file,'exec')
 126     except Exception,err:
 127         py_exc = PyCompileError(err.__class__,err.args,dfile or file)
 128         if doraise:
 129             raise py_exc
 130         else:
 131             sys.stderr.write(py_exc.msg + '\n')
 132             return
 133     if cfile is None:
 134         cfile = file + (__debug__ and 'c' or 'o')
 135     fc = open(cfile, 'wb')
 136     fc.write('\0\0\0\0')
 137     wr_long(fc, timestamp)
 138     marshal.dump(codeobject, fc)
 139     fc.flush()
 140     fc.seek(0, 0)
 141     fc.write(MAGIC)
 142     fc.close()
 143     set_creator_type(cfile)
 144
 145 def main(args=None):
 146     """Compile several source files.
 147
 148     The files named in 'args' (or on the command line, if 'args' is
 149     not specified) are compiled and the resulting bytecode is cached
 150     in the normal manner.  This function does not search a directory
 151     structure to locate source files; it only compiles files named
 152     explicitly.
 153
 154     """
 155     if args is None:
 156         args = sys.argv[1:]
 157     for filename in args:
 158         try:
 159             compile(filename, doraise=True)
 160         except PyCompileError,err:
 161             sys.stderr.write(err.msg)
 162
 163 if __name__ == "__main__":
 164     main()