[Python-Dev] I'd like list.pop to accept an optional second

[Gordon McMillan]

M.-A. Lemburg writes:

> True, sys.lock.acquire() would have to set a flag *not* to release
> the lock until the next call to sys.lock.release(), which then
> clears this flag again. Sort of a lock for the unlocking the lock
> ;-)
> 
> Could this work, or am I having a mind twister somewhere in
> there again ?

Sounds like a critical section to me. On Windows, those are 
lightweight and very handy. You can build one with Python thread 
primitives, but unfortunately, they come out on the heavy side.

Locks come in 4 types, categorized by whether they can be released 
only by the owning thread, and whether they can be acquired 
recursively. The interpreter lock is in the opposite quadrant from a 
critical section, so "sys.lock.freeze()" and "sys.lock.thaw()" have 
little chance of having an efficient implementation on any platform.

A shame. That would be pretty cool.


- Gordon