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From: =?utf-8?Q?Yannick_Duch=C3=AAne_=28Hibou57?= =?utf-8?Q?=29?=
 <yannick_duchene@yahoo.fr>
Newsgroups: comp.lang.ada
Subject: What about a Static_Assertion?
Date: Tue, 23 Jul 2013 20:07:54 +0200
Organization: Ada @ Home
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Xref: number.nntp.dca.giganews.com comp.lang.ada:182660
Date: 2013-07-23T20:07:54+02:00
List-Id: <comp.lang.ada>

Hi Ada novelists,


Don't you believe it would be great to have static assertion just like w=
e  =

have static predicates?

Would play the role of a package Static_Predicate when at package level =
 =

and of an implementation Static_Predicate when at a sub=E2=80=91program =
level.

Assertions are great, but I can't avoid the feeling more distinction  =

between the very different kinds (very different in the implications) of=
  =

assertions would be profitable.

To be more precise, I see at least three kinds:

  * The assertion uses a static expression
  * The assertion uses a constant expression (may not be static!)
  * The assertion uses a variable expression

All three are not the same, and it would be nice to be allowed to  =

explicitly state the kind of assertion we are making. The compiler could=
  =

check what is said to be a constant assertion does not unfortunately  =

depends on a variable entity, and this would help to trust and better  =

understand the consequence of what you read.

I believe this would not be too much a nightmare to be added to any Ada =
 =

202X, this would just requires a check on the kind of the expression use=
d  =

for the assertion, and failure of a static assertion, could be said to  =

make the compilation to necessary fails.

So what about to have `pragma Static_Assertion (=E2=80=A6)`, `pragma  =

Constant_Assertion (=E2=80=A6)` and `pragma Assert (=E2=80=A6)` (the cla=
ssic one, for  =

variable assertions)?

-- =

=E2=80=9CSyntactic sugar causes cancer of the semi-colons.=E2=80=9D [1]
=E2=80=9CStructured Programming supports the law of the excluded muddle.=
=E2=80=9D [1]
[1]: Epigrams on Programming =E2=80=94 Alan J. =E2=80=94 P. Yale Univers=
ity