Contraint error

Contraint error

[Renwick Preston]

My program just started creating a constraint error after I added some Boolean variables
with code that used those variables. I'm thinking that the way I'm using them is what is
causing the problem.

I first initialize them all to False. In my program I have a case statement with some code for
each case. Here is a snippet:

case Month
when June
    If June_Completed then        <- Line added
    < some code here>
    June_Completed := True;    <- Line added
    End if;                                <- Line added
<more code>
end case;

Everything worked fine until I added the lines marked.

What could be the problem?

Ren

Re: Contraint error

[Tucker Taft]

Renwick Preston (rpreston@phoenix.net) wrote:

: My program just started creating a constraint error after I added some Boolean variables
: with code that used those variables. I'm thinking that the way I'm using them is what is
: causing the problem.

: I first initialize them all to False. In my program I have a case statement with some code for
: each case. Here is a snippet:


: case Month
: when June
:     If June_Completed then        <- Line added
:     < some code here>
:     June_Completed := True;    <- Line added
:     End if;                                <- Line added
: <more code>
: end case;

: Everything worked fine until I added the lines marked.

: What could be the problem?

The added lines look a bit suspicious, since you are setting "June_Completed"
to True only if it is already True (your indenting leaves a bit to
be desired ;-).  

In any case, to really diagnose this problem, the reader 
will need a complete but minimal test case which shows the problem.  
A "snippet" will rarely be enough for someone to figure out what is
going wrong.

: Ren

--
-Tucker Taft   stt@inmet.com   http://www.inmet.com/~stt/
Intermetrics, Inc.  Burlington, MA  USA
An AverStar Company

Re: Contraint error

[Matthew Heaney]

Renwick Preston <rpreston@phoenix.net> writes:

You'll have to provide more source code.  There's nothing in the
fragment you did provide that would indicate CE gets raised.

Is June_Completed a subtype?  Do you do this:

declare
   June_Completed : Boolean range False .. False := False;
begin
...
   June_Completed := True;
...
end;

Of course, this really would raise CE.

You're not using a debugger?  

Are you using a compiler that supports display of Exception_Information?


> My program just started creating a constraint error after I added some
> Boolean variables with code that used those variables. I'm thinking
> that the way I'm using them is what is causing the problem.
> 
> I first initialize them all to False. In my program I have a case
> statement with some code for each case. Here is a snippet:
> 
> case Month
> when June
>     If June_Completed then        <- Line added
>     < some code here>
>     June_Completed := True;    <- Line added
>     End if;                                <- Line added
> <more code>
> end case;
> 
> Everything worked fine until I added the lines marked.
> 
> What could be the problem?
> 
> Ren

Re: Contraint error

[Renwick Preston]

I'm using the compiler that came with the book Ada 95 Problem Solving and Program Design. Actually the code should have read

If NOT June_Completed etc but I fixed the problem by adding

When Others
   NULL;

at the end of the CASE statement. I don't understand why that fixed it because all the
possible cases were already covered.

Thanks,
Ren


Matthew Heaney wrote:

> Renwick Preston <rpreston@phoenix.net> writes:
>
> You'll have to provide more source code.  There's nothing in the
> fragment you did provide that would indicate CE gets raised.
>
> Is June_Completed a subtype?  Do you do this:
>
> declare
>    June_Completed : Boolean range False .. False := False;
> begin
> ...
>    June_Completed := True;
> ...
> end;
>
> Of course, this really would raise CE.
>
> You're not using a debugger?
>
> Are you using a compiler that supports display of Exception_Information?
>
> > My program just started creating a constraint error after I added some
> > Boolean variables with code that used those variables. I'm thinking
> > that the way I'm using them is what is causing the problem.
> >
> > I first initialize them all to False. In my program I have a case
> > statement with some code for each case. Here is a snippet:
> >
> > case Month
> > when June
> >     If June_Completed then        <- Line added
> >     < some code here>
> >     June_Completed := True;    <- Line added
> >     End if;                                <- Line added
> > <more code>
> > end case;
> >
> > Everything worked fine until I added the lines marked.
> >
> > What could be the problem?
> >
> > Ren

Re: Contraint error

[Renwick Preston]

I forgot to say that June_Completed was declared as a plain old Boolean.

Ren


Matthew Heaney wrote:

> Renwick Preston <rpreston@phoenix.net> writes:
>
> You'll have to provide more source code.  There's nothing in the
> fragment you did provide that would indicate CE gets raised.
>
> Is June_Completed a subtype?  Do you do this:
>
> declare
>    June_Completed : Boolean range False .. False := False;
> begin
> ...
>    June_Completed := True;
> ...
> end;
>
> Of course, this really would raise CE.
>
> You're not using a debugger?
>
> Are you using a compiler that supports display of Exception_Information?
>
> > My program just started creating a constraint error after I added some
> > Boolean variables with code that used those variables. I'm thinking
> > that the way I'm using them is what is causing the problem.
> >
> > I first initialize them all to False. In my program I have a case
> > statement with some code for each case. Here is a snippet:
> >
> > case Month
> > when June
> >     If June_Completed then        <- Line added
> >     < some code here>
> >     June_Completed := True;    <- Line added
> >     End if;                                <- Line added
> > <more code>
> > end case;
> >
> > Everything worked fine until I added the lines marked.
> >
> > What could be the problem?
> >
> > Ren

Re: Contraint error

[Matthew Heaney]

Renwick Preston <rpreston@phoenix.net> writes:

> I'm using the compiler that came with the book Ada 95 Problem Solving
> and Program Design. Actually the code should have read
> 
> If NOT June_Completed etc but I fixed the problem by adding
> 
> When Others
>    NULL;
> 
> at the end of the CASE statement. I don't understand why that fixed it
> because all the possible cases were already covered.

Was the Month object given a value?  It could be that you tried to
execute a case statement using an object that wasn't initialized, and
you were lucky enough to get an exception.

Re: Contraint error

[Tom Moran]

>When Others
>   NULL;

>at the end of the CASE statement. I don't understand why that fixed it because all the
>possible cases were already covered.
  I doubt it.  How is Month declared?  What is the complete When
structure of the Case statement?  Check *very* carefully and I'll bet
you find that June, and whatever other 'when' values you didn't show
us, are not the only possible values of Month.