kj wrote:
I like Python a lot, and in fact I'm doing most of my scripting in
Python these days, but one thing that I absolutely *****DETEST*****
about Python is that it does allow an internal function to modify
variables in the enclosing local scope. This willful hobbling of
internal functions seems to me so perverse and unnecessary that it
delayed my adoption of Python by about a decade. Just thinking
about it brings me to the brink of blowing a gasket... I must go
for a walk...
OK, I'm better now.
Anyway, I recently wanted to write a internal helper function that
updates an internal list and returns True if, after this update,
the list is empty, and once more I bumped against this hated
"feature". What I wanted to write, if Python did what I wanted it
to, was this:
def spam():
jobs = None
def check_finished():
jobs = look_for_more_jobs()
return not jobs
if check_finished():
return
process1(jobs)
if check_finished():
return
process2(jobs)
if check_finished():
return
process3(jobs)
In application in question, the availability of jobs can change
significantly over the course of the function's execution (jobs
can expire before they are fully processed, and new ones can arise),
hence the update-and-check prior to the calls to process1, process2,
process3.
But, of course, the above does not work in Python, because the jobs
variable local to spam does not get updated by check_finished.
Grrrr!
So you didn't try this?
def spam():
jobs = []
def check_finished():
jobs[:] = look_for_more_jobs()
return not jobs
if check_finished():
return
process1(jobs)
if check_finished():
return
process2(jobs)
if check_finished():
return
process3(jobs)
Actually, I'd refactor and reduce it to this:
def spam():
for proc in [process1, process2, process3]:
jobs = look_for_more_jobs()
if not jobs:
return
proc(jobs)
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