At 11:59 PM 10/18/2005 +1000, Nick Coghlan wrote:
>An idea that was kicked around on c.l.p a long while back was "statement
>local
>variables", where you could define some extra names just for a single simple
>statement:
>
> x = property(get, set, delete, doc) given:
> doc = "Property x (must be less than 5)"
> def get(self):
> try:
> return self._x
> except AttributeError:
> self._x = 0
> return 0
>...
>
>As I recall, the idea died due to problems with figuring out how to allow the
>simple statement to both see the names from the nested block and modify the
>surrounding namespace, but prevent the names from the nested block from
>affecting the surrounding namespace after the statement was completed.
Haskell's "where" statement does this, but the block *doesn't* modify the
surrounding namespace; it's strictly local. With those semantics, the
Python translation of the above could just be something like:
def _tmp():
doc = "blah"
def get(self):
# etc.
# ...
return property(get,set,delete,doc)
x = _tmp()
Which works great except for the part that co_lnotab won't let you identify
that "return" line as being the original expression line, due to the
monotonically-increasing bit. ;)
Note that a "where" or "given" statement like this could make it a little
easier to drop lambda.
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