RE: [vhdl-200x] Modular types

Thanks Tristan - I noticed this behaviour but forgot to comment on it.  For other interested parties, the relevant bit of the LRM is:

--- quote
For the evaluation of a type_conversion that is a value conversion, the operand is evaluated, and then the
value of the operand is converted to a corresponding value of the target type, if any. If there is no value of
the target type that corresponds to the operand value, Constraint_Error is raised; this can only happen on
conversion to a modular type, and only when the operand value is outside the base range of the modular
type.
--- endquote

Now, I can see the reasoning - without an explicit type-conversion (using 'mod), it's more in the VHDL-like "fail as early as possible" mindset.  But perhaps without an explicit type-conversion you shouldn't be allowed to assign an integer to a modular type, so it should fail at compile-time?

I imagine you've written rather more Ada code than I have, so could you elucidate a bit more on the problems the current Ada Behaviour causes please?  You mention it is "error-prone".  What would your preferred behaviour be - to fail at compile-time, or treat all assignments as asking for a "wraparound", or something else entirely?

Thanks,
Martin


-----Original Message-----
From: owner-vhdl-200x@eda.org [mailto:owner-vhdl-200x@eda.org] On Behalf Of tgingold@free.fr
Sent: 25 June 2014 19:39
To: vhdl-200x@eda.org
Subject: Re: [vhdl-200x] Modular types

Hello,

> So, are there any features you would like which are not mentioned?
> Constraints which do not make sense?

Ada made a mistake for type conversion to modular type: the expression is not reduced, which is not intuitive and error prone.  (In Ada, a type conversion of a negative value to a modular type raises an error).
Don't follow that!

Regards,
Tristan.

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