PhobosWatch: manifest => enum

["Jérôme M. Berger"]

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Walter Bright wrote:
> Jérôme M. Berger wrote:
>> Walter Bright wrote:
>>> Yes, that could be done, but we're still stymied by the problem that we
>>> are unable to declare a constant of type 'int', only 'const(int)'.
>>
>>     I don't see any situation in which we would need a constant of type
>> "int" instead of "const (int)" or "invariant (int)". After all, if
>> it is a *constant*, it should be either "const" or "invariant", no?
> 
> Consider the following:
> 
>     const int X = 3;
>     auto i = X;
>     i = 4;        // error, i is const
> 
> Essentially, it would make type inference far less useful.

	OTOH, having something that's a constant but has type "int" instead
of "const (int)" or "invariant (int)" could cause problems with
generic programming. For example with something like this:

- -------------------->8====================

static if (is (typeof (x) : int)
   x = 42;
else static if ((is (typeof (x) : const (int))
                || (is (typeof (x) : invariant (int)))
   processImmutableInts();
else
   static assert (0, "Can only handle ints");

====================8<--------------------

	If "x" is in fact a manifest constant, this code will think it is
mutable and try to assign to it but the compiler will then refuse
the assignment...

		Jerome
- --
+------------------------- Jerome M. BERGER ---------------------+
|    mailto:jeberger at free.fr      | ICQ:    238062172            |
|    http://jeberger.free.fr/     | Jabber: jeberger at jabber.fr   |
+---------------------------------+------------------------------+
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