I doubted whether or not to write, but since Guido has already touched a
similar topic (see "Live variable analysis -> earlier release"), so will
I write.
It is common to assign some values which are never used to variables
because the syntax demands this. For example:
head, _, rest = path.partition('/')
first, second, *_ = line.split()
for _ in range(10): ...
[k for k, _ in pairs]
What if make such assignments no-op? It will only work with some
limitations:
1. The variable is local. Not global, not nonlocal, not cell.
2. The variable name must start with '_'. Otherwise there would be
larger risk of breaking a legal code which uses locals() with
str.format() or like.
3. "del" is considered a use of the variable. So explicitly deleted
variables will not be optimized out.
4. Star-assignment still consumes the iterator. It just might not to
keep all values in memory.
STORE_FAST will be replaced with POP_TOP in these cases.
I wrote some code few weeks ago, and it is not too complex. My doubts
are only that the benefit of the optimization with the above limitations
is very restricted.
_______________________________________________
Python-ideas mailing list -- python-ideas@python.org
To unsubscribe send an email to python-ideas-le...@python.org
https://mail.python.org/mailman3/lists/python-ideas.python.org/
Message archived at
https://mail.python.org/archives/list/python-ideas@python.org/message/PH7R2R3FTLT3I734FTTSN57P4PKUZ7L7/
Code of Conduct: http://python.org/psf/codeofconduct/
