Re: Press Release - Ada 2012 Language Standard Approved by ISO

[sbelmont700@gmail.com]

On Sunday, December 23, 2012 6:38:21 PM UTC-5, Shark8 wrote:
> On Sunday, December 23, 2012 2:08:53 AM UTC-6, Dmitry A. Kazakov wrote:
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> > 
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> >  Contracted exceptions is an urgent need.
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> 
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> There are contracted exceptions, of a sort -- the LRM guarantees that the predefined relational operator will not raise an exception and the predefined operators on integers will only raise NUMERIC_ERROR ( http://archive.adaic.com/standards/83lrm/html/lrm-04-05.html ) -- of course that's an external contract.
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> The ability to have such guarantees applied to the programer's Ada text would indeed be a boon; perhaps using an aspect of the following form:
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>    Exceptions => [ NOT NULL | NULL | "EXCEPTION_NAME"[, OR "EXCEPTION_NAME"]]
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> 
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> Where EXCEPTION_NAME would map to either predefined exceptions or visible user-defined exceptions, NULL would assert that the procedure raises no exceptions, and NOT NULL would be what we have now (subprogram can raise any exception).
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> The problem with the above is that there's some exceptions which are dependent on the [executing] environment at Run-time (STORAGE_ERROR springs to mind).

Recall that exception specifications in C++ was a god-awful nightmare, and has since been depreciated.  It makes it nearly impossible to write anything useful, since if subprogram A raises exception E, then any subprogram A calls during its body must also only ever raise E, and it's turtles all the way down.

-sb