const objects (was Re: Death to tuples!)

[Tom Anderson]

On Wed, 14 Dec 2005, Steven D'Aprano wrote:

> On Wed, 14 Dec 2005 10:57:05 +0100, Gabriel Zachmann wrote:
>
>> I was wondering why python doesn't contain a way to make things "const"?
>>
>> If it were possible to "declare" variables at the time they are bound 
>> to objects that they should not allow modification of the object, then 
>> we would have a concept _orthogonal_ to data types themselves and, as a 
>> by-product, a way to declare tuples as constant lists.
>
> In an earlier thread, somebody took me to task for saying that Python 
> doesn't have variables, but names and objects instead.

I'd hardly say it was a taking to task - that phrase implies 
authoritativeness on my part! :)

> This is another example of the mental confusion that occurs when you 
> think of Python having variables.

What? What does this have to do with it? The problem here - as Christopher 
and Magnus point out - is the conflation in the OP's mind of the idea of a 
variable, and of the object referenced by that variable. He could have 
expressed the same confusion using your names-values-and-bindings 
terminology - just replace 'variable' with 'name'. The expression would be 
nonsensical, but it's nonsensical in the variables-objects-and-pointers 
terminology too.

> Some languages have variables. Some do not.

Well, there is the lambda calculus, i guess ...

tom

-- 
The sky above the port was the colour of television, tuned to a dead
channel