Explicit variable declaration

[Steve Holden]

Filip Gruszczyński wrote:
>>  You mean the type? Not in 2.x, but in 3.x, there are function
>>  annotations:
>>
>>  def a_function(arg1: int, arg2: str) -> None: pass
> 
> Nope, I don't like types ;-) 3.x seems pretty revolutionary, and this
> typing can be appreciated by some people.
> 
>> Declaring what about them? If you mean declaring the type, remember
>> that Python deliberately allows any name to be bound to any object;
>> type declarations can't be enforced without losing a lot of the power
>> of Python.
> 
> Just declaring, that they exist. Saying, that in certain function
> there would appear only specified variables. Like in smalltalk, if I
> remember correctly.
> 
Icon has (had?) the same feature: if the "local" statement appeared then 
the names listed in it could be assigned in the local namespace, and 
assignment to other names wasn't allowed.

A lot of people assume that's what the __slots__ feature of the new 
object model is for, but it isn't: it's actually a memory conservation 
device for circumstances when millions of objects must be created in an 
application.

regards
  Steve
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