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From: Victor Porton <porton@narod.ru>
Newsgroups: comp.lang.ada
Subject: Re: Instantiations of a generic with often encountered arguments
Date: Mon, 27 Nov 2017 04:02:20 +0200
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Xref: feeder.eternal-september.org comp.lang.ada:49170
Date: 2017-11-27T04:02:20+02:00
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Dmitry A. Kazakov wrote:

> On 2017-11-26 01:04, Victor Porton wrote:
>> Is it a good practice to declare "centralized" (that is in the same
>> package as a generic packages is defined in, or in a child unit)
>> instantiations of a generic package with common (that is often
>> encountered, such as Integer, String, etc.) generic parameters?
> 
> Yes, Ada library does so for standard types.

Where?!

> Sometimes a set of related generic packages is instantiated in a third
> package which is then used. E.g. you have a generic vector, matrix,
> solver defined over the same type.
> 
>> In C++ this is not a problem, because there a template is instantiated
>> whenever one needs it.
> 
> Because in C++ templates are 100% macros, whereas in Ada generic
> instances can be shared, theoretically at least, and should be treated
> as real packages.
> 
> Then C++ templates have structrual matching, all instances/expansions
> with same parameters are same. It is no matter where you would expand a
> macro. Ada uses nominal matching of generic instances and they can be
> scoped.

I received what seems two opposite opinions on my question.

Please state the reasons.

I am now in analysis-paralysis of whether to define instantiations for often 
encountered types in advance (globally) or immediately before use.

-- 
Victor Porton - http://portonvictor.org