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From: Niklas Holsti <niklas.holsti@tidorum.invalid>
Newsgroups: comp.lang.ada
Subject: Re: On naming space and the good use of qualified expression
Date: Fri, 19 Jan 2018 20:37:15 +0200
Organization: Tidorum Ltd
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Xref: reader02.eternal-september.org comp.lang.ada:50007
Date: 2018-01-19T20:37:15+02:00
List-Id: <comp.lang.ada>

On 18-01-19 19:51 , Mehdi Saada wrote:
> At that point of the program, I have three "/" operators visibles:
> function "/" (A: T_Rational, B: T_Rational) return T_Rational;
> function "/" (A: T_Integer, B: T_Integer) return T_Integer;
> function "/" (A: T_Integer, B: T_Integer) return T_Rational; -- my constructor method
> which makes this expression ambiguous:
> Result.Coef(Ind) := Poly_A.Coef(Ind+1) * (Ind+1)/1;
> (Coef is an array of T_Rational, Ind is of the same type as the index)
>
> For the first time, I grasp what "namespace polution" means.
> I overestimated the compiler's smartness. I tried then:
> Result.Coef(Ind) := Poly_A.Coef(Ind+1) * T_Rational'((Ind+1)/1);
> As I thought qualified expression were a means to inform the compiler
> of the intended type of the parenthesed expression, so that it could
> choose based on the litteral inside AND the different visible homonymous
> functions.

Perhaps you also have a set of overloaded "+" operators, and the 
confusion is in the expression Ind+1 ?

That is, should the computation be:

   Ind + 1, as Integer + Integer -> Rational

followed by

   (Ind + 1) / 1, as Rational / Integer -> Rational ?

Or should it be:

    Ind + 1, as Integer + Integer -> Integer

followed by

    (Ind + 1) / 1, as Integer / Integer -> Rational ?

Just a guess, of course...

-- 
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
       .      @       .