To someone who's a novice to this, could someone explain to me why it has to be an existing keyword at all? Since not identifiers are valid in that context anyway, why couldn't it be a new keyword that can still be used as an identifier in valid contexts? For example (not that I advocate this choice of keyword at all): def foo(bar reinitialize_default []): # <-- it's a keyword here reinitialize_default = "It's an identifier here!" That would be a syntax error now and if it were defined as a keyword only in that context it wouldn't introduce backwards compatibility problems and wouldn't force us to reuse an existing keyword in a context that may be a bit of a stretch. Is there a reason that this wouldn't be a viable approach? On 2009-05-13, MRAB <google@mrabarnett.plus.com> wrote:
Jacob Holm wrote:
Pascal Chambon wrote:
One last idea I might have : what about something like
* def myfunc(a, b, c = yield []): pass*
[...], but there is no interpretation conflict for the parser, and we might quickly get used to it
I am surprised that there is no conflict, but it looks like you are technically right. The parentheses around the yield expression are required in the following (valid) code:
def gen(): ... def func(arg=(yield 'starting')): ... return arg ... yield func ... g = gen() g.next() 'starting' f = g.send(42) f() 42
I would hate to see the meaning of the above change depending on whether the parentheses around the yield expression were there or not, so -1 on using "yield" for this.
I'm +0 on the general idea of adding a keyword for delayed evaluation of default argument expressions.
There's the suggestion that Carl Johnson gave:
def myfunc(a, b, c else []): pass
or there's:
def myfunc(a, b, c def []): pass
where 'def' stands for 'default' (or "defaults to"). _______________________________________________ Python-ideas mailing list Python-ideas@python.org http://mail.python.org/mailman/listinfo/python-ideas