Re: Types, packages & objects : the good old naming conventions question (without religious ware)

[Niklas Holsti <niklas.holsti@tidorum.invalid>]

Stephen Leake wrote:
> Niklas Holsti <niklas.holsti@tidorum.invalid> writes:
> 
>> Dmitry A. Kazakov wrote:
>>
>>> Consider it this way, if _Type is felt appropriate then that is
>>> semantically equivalent to types having a separate name space. The latter
>>> could be introduced in Ada at any time, being fully backward compatible.
>> I'm not sure about the backward compatibility. For one thing, the
>> Size attribute may have a different value for a type and for an object
>> of the type. This means that given an object declaration "List :
>> List", where the latter List is a type name, the expression List'Size
>> would be ambiguous and could have a different value for the object
>> List and the type List.
> 
> The definition of "backward compatible" is "all existing legal
> programs will still be legal".

Yes, you and Dmitry are right, it would be backward compatible in this 
sense (which is the common sense). I was thinking that using the same 
names for types and objects would create problems, for example this 
ambiguity, and so it would not be "compatible" to take an existing legal 
program and change type names by, for example, removing "_Type" suffixes.

> This ambiguity does not exist in existing legal programs.

Agreed.

> It is a good reason not to have separate name spaces; how would we
> resolve the ambiguity?

Right, that was the problem I had in mind. One way would be to have two 
different attributes, 'Size for objects and 'Type_Size for types. But 
that causes backward-compatibility problems unless 'Size is also 
accepted for types if the name before the 'Size is unambiguously a type 
name. It may also be difficult for compilers to resolve ambiguous names 
based on the kind of attribute applied to the name.

-- 
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
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