The script in itself is an interesting example of recursion down a
directory tree and using regular expressions (the "regexp" module).
Install the script as "demo/scripts/classfix.py". To convert all
library and demo modules, chdir to the top of the Python tree and
issue this command:
python demo/scripts/classfix.py lib demo
There is no need to rebuild Python after the script has run.
--Guido van Rossum, CWI, Amsterdam <guido@cwi.nl>
"No, no really, we're just not religious thank you."
------------------------------- cut here -------------------------------
#! /usr/local/python
# Fix Python source files to use the new class definition syntax,
# i.e.,
# class C(base, base, ...): ...
# instead of
# class C() = base(), base(), ...: ...
#
# Command line arguments are files or directories to be processed.
# Directories are searched recursively for files whose name looks
# like a python module.
# Symbolic links are always ignored (except as explicit directory
# arguments). Of course, the original file is kept as a back-up
# (with a "~" attached to its name).
#
# Undoubtedly you can do this using find and sed, but this is
# a nice example of Python code that recurses down a directory tree
# and uses regular expressions. Also note several subtleties like
# preserving the file's mode and avoiding to even write a temp file
# when no changes are needed for a file.
#
# Changes made are reported to stdout in a diff-like format.
import sys
import regexp
import posix
import path
import string
from stat import *
err = sys.stderr.write
dbg = err
rep = sys.stdout.write
def main():
bad = 0
if not sys.argv[1:]: # No arguments
err('usage: classfix file-or-directory ...\n')
sys.exit(2)
for arg in sys.argv[1:]:
if path.isdir(arg):
if recursedown(arg): bad = 1
elif path.islink(arg):
err(arg + ': will not process symbolic links\n')
bad = 1
else:
if fix(arg): bad = 1
sys.exit(bad)
ispython = regexp.compile('^[a-zA-Z0-9_]+\.py$').match # This is a method!
def recursedown(dirname):
dbg('recursedown(' + `dirname` + ')\n')
bad = 0
try:
names = posix.listdir(dirname)
except posix.error, msg:
err(dirname + ': cannot list directory: ' + `msg` + '\n')
return 1
for name in names:
if name in ('.', '..'): continue
fullname = path.join(dirname, name)
if path.islink(fullname): pass
elif path.isdir(fullname):
if recursedown(fullname): bad = 1
elif ispython(name):
if fix(fullname): bad = 1
return bad
# This expression doesn't catch *all* class definition headers,
# but it's darn pretty close.
classexpr = '^([ \t]*class +[a-zA-Z0-9_]+) *\( *\) *((=.*)?):'
findclass = regexp.compile(classexpr).match # This is a method!
baseexpr = '^ *(.*) *\( *\) *$'
findbase = regexp.compile(baseexpr).match # This is a method, too!
def fix(filename):
## dbg('fix(' + `filename` + ')\n')
try:
f = open(filename, 'r')
except IOError, msg:
err(filename + ': cannot open: ' + `msg` + '\n')
return 1
head, tail = path.split(filename)
tempname = path.join(head, '@' + tail)
tf = None
# If we find a match, we rewind the file and start over but
# now copy everything to a temp file.
while 1:
line = f.readline()
if not line: break
res = findclass(line)
if not res:
if tf: tf.write(line)
continue
if not tf:
try:
tf = open(tempname, 'w')
except IOError, msg:
f.close()
err(tempname+': cannot create: '+`msg`+'\n')
return 1
rep(filename + ':\n')
# Rewind the input file and start all over:
f.seek(0)
continue
a0, b0 = res[0] # Whole match (up to ':')
a1, b1 = res[1] # First subexpression (up to classname)
a2, b2 = res[2] # Second subexpression (=.*)
head = line[:b1]
tail = line[b0:] # Unmatched rest of line
if a2 = b2: # No base classes -- easy case
newline = head + ':' + tail
else:
# Get rid of leading '='
basepart = line[a2+1:b2]
# Extract list of base expressions
bases = string.splitfields(basepart, ',')
# Strip trailing '()' from each base expression
for i in range(len(bases)):
res = findbase(bases[i])
if res:
(x0, y0), (x1, y1) = res
bases[i] = bases[i][x1:y1]
# Join the bases back again and build the new line
basepart = string.joinfields(bases, ', ')
newline = head + '(' + basepart + '):' + tail
rep('< ' + line)
rep('> ' + newline)
tf.write(newline)
f.close()
if not tf: return 0 # No changes
# Finishing touch -- move files
# First copy the file's mode to the temp file
try:
statbuf = posix.stat(filename)
posix.chmod(tempname, statbuf[ST_MODE] & 0x7777)
except posix.error, msg:
err(tempname + ': warning: chmod failed (' + `msg` + ')\n')
# Then make a backup of the original file as filename~
try:
posix.rename(filename, filename + '~')
except posix.error, msg:
err(filename + ': warning: backup failed (' + `msg` + ')\n')
# Now move the temp file to the original file
try:
posix.rename(tempname, filename)
except posix.error, msg:
err(filename + ': rename failed (' + `msg` + ')\n')
return 1
# Return succes
return 0
main()