Declaring variables

[Steve Holden]

Matimus wrote:
> On May 16, 9:57 am, HMS Surprise <j... at datavoiceint.com> wrote:
>> I looked in the language but did not find a switch for requiring
>> variables to be declared before use.
>>
>> Is such an option available?
>>
>> Thanks,
>>
>> jvh
> 
> You do have to declare a variable before use. You do so by assigning
> it a value. You can't use a variable before it has been assigned. In
> some ways this is less ambiguous than even C where you can declare a
> variable without assigning a value. Also note that this caries the
> type information, since the variable is of whatever type was assigned
> to it. The only thing it doesn't do is give a unique flag that says
> "hey this is where I'm declared", although I suppose you could do that
> with a comment.
> 
Strictly, the variable has no type at all (and strictly your "variables" 
are actually names bound to values in a namespace, and it's the values 
that are typed).

We shouldn't ignore the fact that declarations unambiguously say "the 
programmer intends to use such-and-such a name for a value of a specific 
type". Contrast this with a Python program where one path makes an 
assignment (binding) to a name while another path doesn't, resulting in 
a later NameError.

regards
  Steve
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