[Python-Dev] genexps slow?

[Michael Hudson]

"Tim Peters" <tim.one at comcast.net> writes:

>  Resuming a generator function is a lot cheaper than calling a
> function, but there's still a non-trivial amount of code to get in
> and out of eval_frame() each time, which the listcomp version gets
> to skip.

This is something that occurred to me a while ago: how many opcodes
does a typical invocation of eval_frame actually execute?  A little
script told me that the median length of functions in Lib/*.py was 38
instructions (or 52 bytes) IIRC, but obviously a dynamic count is far
more interesting.  If the number is fairly small (and honestly, I have
no idea), the set up and tear down code becomes much more significant
than one might think.

I didn't think much about the code to get *out* of eval_frame.

Cheers,
mwh

-- 
  I love the way Microsoft follows standards.  In much the same
  manner that fish follow migrating caribou.           -- Paul Tomblin
               -- http://home.xnet.com/~raven/Sysadmin/ASR.Quotes.html