SCons

SCons is a great make replacement written in Python. It offers the following goodies (and many more):

• Cross platform. Same script will compile your sources for Linux or Windows or ...


• Support many tools out of the box (such as gcc/VC/java/tar ...)


• Calculate if a file has change by digital signature
(and not by time stamp)

• Automatically cleans after itself (no more make clean)
  

Scons Makefile is called SConstruct, here is a simple one:

Program("hw", ["hw.c"])

Which tells scons to build an executable called hw from the source file hw.c

Calling scons on Linux will produce:

[15:10] /tmp/hw $scons
scons: Reading SConscript files ...
scons: done reading SConscript files.
scons: Building targets ...
gcc -o hw.o -c hw.c
gcc -o hw hw.o
scons: done building targets.
[15:10]

and on Windows it finds VC and invokes it:

C:\Temp\hw>scons
scons: Reading SConscript files ...
scons: done reading SConscript files.
scons: Building targets ...
cl /nologo /c hw.c /Fohw.obj
hw.c
link /nologo /OUT:hw.exe hw.obj
scons: done building targets.
C:\Temp\hw>

Cleaning is simple as well:

[15:19] /tmp/hw $scons -c
scons: Reading SConscript files ...
scons: done reading SConscript files.
scons: Cleaning targets ...
Removed hw.o
Removed hw
scons: done cleaning targets.
[15:19] /tmp/hw $

All of this in one line of SConstruct.

(Shameless plug: See here for a longer article on the subject)

Better dir

The builtin dir command is very useful. However it does not help that much when an object has many attributes.

I have a little function called la in my $HOME/.pythonrc.py

def la(obj, key=None, ignore_case=1):
    '''List all attributes of object'''
    import re
    if key:
        if ignore_case:
            flags = re.I
        else:
            flags = 0
        func = re.compile(key, flags).search

    else:
        func = None
    print "\n".join(filter(func, dir(obj)))

This prints the attributes of an object one per line and also gives you the ability to search for specific items.

>>> from user import la
>>> import wx
>>> la(wx, "open")
ART_FILE_OPEN
ART_FOLDER_OPEN
EVT_MENU_OPEN
ID_OPEN
OPEN
Process_Open
wxEVT_MENU_OPEN
>>> 

(Sun Aug 27 14:03:24 JDT 2006: Added regular expression to "la")

Script Template

Sorry for the long delay, times are interesting around here.

Since many of my scripts share the same structure, I have a little template that I use for new scripts. I have a makepy command that copies this template to a new script.

#!/usr/bin/env python
''' '''

# Miki Tebeka 

def main(argv=None):
    if argv is None:
        import sys
        argv = sys.argv

    from optparse import OptionParser

    parser = OptionParser("usage: %prog ")

    opts, args = parser.parse_args(argv[1:])
    if len(args) != 1:
        parser.error("wrong number of arguments") # Will exit

if __name__ == "__main__":
    main()

As you can see, there is a place holder for the script documentation string. There is also a main function (inspired by Guido) and also a template for calling optparse command line parser module (most of my scripts take one argument, so this is the default).