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From: 18k11tm001@sneakemail.com (Russ)
Newsgroups: comp.lang.ada
Subject: Re: += in ada
Date: 16 Oct 2003 01:49:13 -0700
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Stuart Palin <stuart.palin@0.0> wrote in message news:<3F8BC74F.2CFBFF37@0.0>...
> Regarding this vociferous debate on the matter of operators
> such as ":+=" (or however you choose to denote it).
> 
> May I ask how it might be squared with the ability to
> declare and rename other operator functions and using such
> operators in a post-fix fashion.
> 
> In the moments of idle curiosity I have given to the matter
> the only reasonable interpretation would seem to be to treat
> them not as specific operators in their own right, but as a
> syntactic equivalent to the use of a more basic operator.
> 
> e.g.  a :+= b;  is equivalent to a := a + b;
> 
> Then any redefinition of "+" is inherited by ":+=".  But

Actually, a competent programmer will define the "+" operator in terms
of the ":+" operator rather than vice versa, because the ":+" is
usually more efficient (since it has no need for temporaries and extra
copying).

> this does not necessarily help clarify any post-fix form of
> the operator.

> Treating them as operator functions in their own right seems
> to create difficulties in defining a workable specification
> for the function or leads to the possibility of
> "interesting" expressions such as:
>   a :+= ":+="(b, c);

Actually, the augmented assignment operators are symbolic of
procedures rather than functions. They should not return anything.
(They can return something in C++, but thats only because C++, like C,
does not distinguish between functions and procedures.)