On Sun, 16 Jul 2017, Ondrej Pokorny wrote:
On 15.07.2017 21:39, Jonas Maebe wrote:
On 15/07/17 21:33, laza...@kluug.net wrote:
Am Sa., Jul. 15, 2017 21:07 schrieb Jonas Maebe <jo...@freepascal.org>:
I have said from the start that it is possible to store invalid values
in variables through the use of a.o. pointers (which is what the class
zeroing does), explicit typecasts and assembly.
In this case you must not restrict us to work with invalid values in a
deterministic way.
You can if you always use explicit typecasts to different types and access
everything through pointers and assembly. But then the question is why you
want to use a restrictive type in the first place.
Either you declare a type as only holding a limited set of data when valid
and assume it behaves as such, or you don't. A mixture is the worst of both
worlds: no type safety and unexpected behaviour when something else assumes
the type declaration actually means what is written.
The problem is that you yourself force us to the mixture that "is the worst
of both worlds".
On the one hand you say that the compiler can generate invalid values and on
the other hand you say that the compiler can assume the enum holds only valid
values. For now, there is absolutely no range checking and type safety for
enums - so you can't use it as an argument.
You are missing the point of an enumerated.
The whole point of using an enumerated is that range checking
*is not necessary*, because the values are 'by definition' correct.
If the compiler cannot assume this, you're just using an integer with
some named values. Hardly worth a separate type.
Michael.
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