On Wed, 06 Apr 2005 00:23:01 GMT, [EMAIL PROTECTED] (Bengt Richter) wrote:
>I don't know of anything other than the compiler and cpython sources.
>The byte codes are not all the same from version to version, since
>added language features may require new byte code operations, at least
>for efficiency, and (as our postings here show ;-) explaining code
>clearly is as much of a job as writing it. Fortunately, python code
>is pretty readable, and there is a lot of interesting reading in
>
> Python-2.4xxx\Lib\compiler\ and Python-2.4xxx\Lib\compiler\
>
>on your disk if you download the source installation. Lots of
>other goodies as well like demo code etc.
Thanks, I've already downloaded the source as well as CVS, although I
don't have a resent version of VisualC++. I Tried the Express version
8.0 since it's free, but it fails on the library with link errors.
:-/, Not that I expected it to work since nothing I could find said
it would. Probably easier to load up linux. But I don't need a
compiler to read the source.
>
>One of the original examples of decorating was to replace the
>staticmethod and classmethod function calls that had to be done
>after the method defs. So the simplest view goes back to
>
> @deco
> def foo(): pass
>
>being the equivalent (except if deco raises and exception) of
>
> def foo(): pass
> foo = deco(foo)
>
>The plain name @deco was then allowed to become a simple xxx.yyy(zzz,...)
>expression
>returning a callable that would serve like the decorator function a bare name
>normally
>referred to. And then the mechanism could be cascaded. I suggest looking at the
>code for the simplest cascade of normal decorators. E.g., (putting the example
>in
>the body of a function makes dis.dis easy ;-)
So the @decorator functionality was a very small incremental change to
the pre compiler. That also explains the nesting behavior of stacked
decorators. A small change with a worth while functionality. :-)
Looks like the @decorator is pseudo function limited to a single
callable as it's body.
(experimenting with a different syntax)
@deco(a):
def function(x): pass
function = deco(a)(function)(x)
Stacked, it would be:
@deco1(a):
@deco2(b):
def function(x):
return x+1
function = deco2(a)(function)(x)
function = deco1(b)(function)(x)
Each subsequent stacked [EMAIL PROTECTED] statement redefines "function" when it
exits.
If I have this correct, this would be the equivalent long hand of two
stacked [EMAIL PROTECTED] expressions.
Cheers,
Ron
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