[Tutor] hash.update( argv[0] )

[Danny Yoo]

> where outputVersion is a manual set variable in the program
> (so I have to purge all the imageFile each time I adjust the
> program.  maybe this is going to work, less progressive approach
                                               ^^^^^^^^^^^

Hi George,

Just to make sure: by "progressive", I meant the technical concept:

     progressive: read the file a chunk at a time rather than sucking the
                  file all at once.

*grin*


>    # Use a hash of the parameters to generate a cache filename.
>    hash = sha.new(texData)
>    hash.update( "%d %d" % (density, int(texMag)) )
>    hash.update( open(argv[0]).read() )
>    name = hash.hexdigest()
>    imageFile = "%s/%s.%s" % (imagePath, name, 'png')
>
> I cannot test till the evening because of $WORK; but is that a
> good way to do it?

Yes, I think this will work.

One thing that it may not be robust against is changes to the current 
working directory.  I'd recommend capturing the program's filename at the 
program's entry as an absolute-pathed variable, so that if we shake things 
up by changing current working directory, we should still be able to work.

The os.path module may be useful here:

     http://www.python.org/doc/lib/module-os.path.html

It has a few path-normalizing functions that should make this a relatively 
easy fix.