A = X > Y ? X : Y
evan at 4-am.com
Thu Feb 10 09:46:22 EST 2000
Michael Hudson <mwh21 at cam.ac.uk> wrote in message
news:m33dr1wj40.fsf at atrus.jesus.cam.ac.uk...
> > Sure it does. They're called bytecodehacks :-)
> Thanks for the plug.
I was hoping to thank you in person at IPC8; byecodehacks has been very good
to me :-)
> > Even better, they are
> > *semantic* macros
> Evan, what are you talking about here?
I may be abusing terminology horribly here, but my point was that I can get
effects from bch that I can't imagine getting from mere cpp
text-substitution stuff. For instance, my PythonMethods Zope product uses
bch to make a function definition "safe". It ensures that no reference is
made to variables beginning with '_', that no assignment or deletion of
elements/attributes/slices takes place, and that nothing is imported or
exec'd. I don't make any of these effects dependent on the presence of a
bch 'macro' name, but I *could*.
Another example I've thought about implementing is a 'loopexit' macro, which
would be used thusly:
for x in xxx:
if stitch in time:
raise 'Found Stitch'
except loopexit('Found Stitch'):
print 'Found it!'
...transforming the 'raise' into a simple jump as in my proposed 'try:
Try that with normal macros! The only two limitations I find on bch are the
need to explicitly process functions, and the fact that the unprocessed code
must be syntactically correct normal Python; No wholesale redefinition of
Evan @ digicool
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