Elaboration Problem

Elaboration Problem

[Decker, Christian R]

I have a constant being declared inside a generic where the value being used
for the constant is obtained from
a lookup table.  Later on in a subprogram the constant value is used rather
than the lookuptable and to my suprise
the constant is not correct.

if i do a comparison between the constant and the lookup table value in the
same subprogram they are not equal.

Has anyone ever seen behavior like this?

Is this an elaboration problem where  the constant is being assigned a value
before the Ada package that the
lookup table resides in elaborates?

any suggestions?



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Re: Elaboration Problem

[Matthew Heaney]

On 09 Jun 1999 06:26, cdecker@snet.net (Decker, Christian R) wrote:

> I have a constant being declared inside a generic where the value being used
> for the constant is obtained from
> a lookup table.  Later on in a subprogram the constant value is used rather
> than the lookuptable and to my suprise
> the constant is not correct.
> 
> if i do a comparison between the constant and the lookup table value in the
> same subprogram they are not equal.
> 
> Has anyone ever seen behavior like this?
> 
> Is this an elaboration problem where  the constant is being assigned a value
> before the Ada package that the
> lookup table resides in elaborates?
> 
> any suggestions?


Post some elided code, and we will try to diagnose the problem.  Without
actual code, it's difficult to understand what's going on.

Also, please state what language you're using (83 vs 95), and which
compiler.

Re: Elaboration Problem

[Stephen Leake]

cdecker@snet.net (Decker, Christian R) writes:

> I have a constant being declared inside a generic where the value being used
> for the constant is obtained from
> a lookup table.  Later on in a subprogram the constant value is used rather
> than the lookuptable and to my suprise
> the constant is not correct.
> 
> if i do a comparison between the constant and the lookup table value in the
> same subprogram they are not equal.
> 
> Has anyone ever seen behavior like this?
> 
> Is this an elaboration problem where  the constant is being assigned a value
> before the Ada package that the
> lookup table resides in elaborates?
> 
> any suggestions?

Elaboration order problems should raise Program_Error; make sure you
have elaboration checks turned on.

Otherwise, post the code, so we can see what the code is really doing
(often different from what you thought you wanted the code to do :).

-- Stephe

Re: Elaboration Problem

[Robert Dewar]

In article <uaeu1xx6y.fsf@gsfc.nasa.gov>,
  Stephen Leake <Stephen.Leake@gsfc.nasa.gov> wrote:
> Elaboration order problems should raise Program_Error; make
> sure you have elaboration checks turned on.

Note that the above advice is probably misleading when using
GNAT, since elaboration checking is by default done statically
at compile time (this is a simplification -- see the chapter
on elaboration checking in the GNAT user's guide).

Robert Dewar
Ada Core Technologies


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