Re: [TCLCORE] TIP #320: Improved Variable Handling in the Core Object System

[Will D. <wi...@wj...>]

On Jun 15, 2008, at 5:43 AM, Donal K. Fellows wrote:
> Arnulf Wiedemann wrote:
>> That looks ok for itcl as far as I can see at the moment. Will  
>> method speak2
>> work as I have written it (see below)?
>
> Yes.

In Donal's example, we have an instance variable, utterance, declared
for the "animal" class; the variable is visible without declaration in
subclass "cat"'s methods, e.g., "speak2".

This strikes me as dangerous; a new instance variable added to an
ancestor class that has the same name as a local variable used in a
subclass method can break the subclass method.

Donal, in your example, "dog" declares utterance explicitly; does that
make any difference?  Given that method "cat"'s "speak2" can see
utterance, it would appear not.

Will

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