Added docstrings.

Added an optional third parameter giving the purported filename for
error messages from the module.

Append a newline to the code string if needed.

Lib/py_compile.py

@@ -1,17 +1,46 @@
-# Routine to "compile" a .py file to a .pyc file.
-# This has intimate knowledge of how Python/import.c does it.
-# By Sjoerd Mullender (I forced him to write it :-).
+"""Routine to "compile" a .py file to a .pyc (or .pyo) file.
+
+This module has intimate knowledge of the format of .pyc files.
+"""
 
 import imp
 MAGIC = imp.get_magic()
 
 def wr_long(f, x):
+    "Internal; write a 32-bit int to a file in little-endian order."
     f.write(chr( x        & 0xff))
     f.write(chr((x >> 8)  & 0xff))
     f.write(chr((x >> 16) & 0xff))
     f.write(chr((x >> 24) & 0xff))
 
-def compile(file, cfile = None):
+def compile(file, cfile=None, dfile=None):
+    """Byte-compile one Python source file to Python bytecode.
+
+    Arguments:
+
+    file:  source filename
+    cfile: target filename; defaults to source with 'c' or 'o' appended
+	   ('c' normally, 'o' in optimizing mode, giving .pyc or .pyo)
+    dfile: purported filename; defaults to source (this is the filename
+	   that will show up in error messages)
+
+    Note that it isn't necessary to byte-compile Python modules for
+    execution efficiency -- Python itself byte-compiles a module when
+    it is loaded, and if it can, writes out the bytecode to the
+    corresponding .pyc (or .pyo) file.
+
+    However, if a Python installation is shared between users, it is a
+    good idea to byte-compile all modules upon installation, since
+    other users may not be able to write in the source directories,
+    and thus they won't be able to write the .pyc/.pyo file, and then
+    they would be byte-compiling every module each time it is loaded.
+    This can slow down program start-up considerably.
+
+    See compileall.py for a script/module that uses this module to
+    byte-compile all installed files (or all files in selected
+    directories).
+
+    """
     import os, marshal, __builtin__
     f = open(file)
     try:
@@ -20,7 +49,9 @@ def compile(file, cfile = None):
 	timestamp = long(os.stat(file)[8])
     codestring = f.read()
     f.close()
-	codeobject = __builtin__.compile(codestring, file, 'exec')
+    if codestring and codestring[-1] != '\n':
+	coestring = codestring + '\n'
+    codeobject = __builtin__.compile(codestring, dfile or file, 'exec')
     if not cfile:
 	cfile = file + (__debug__ and 'c' or 'o')
     fc = open(cfile, 'wb')