On Wed, 01 Sep 2010 11:06:51 +0300, Rainer Deyke <rain...@eldwood.com>
wrote:
On 8/31/2010 19:46, bearophile wrote:
But you can use const for constants that are known at run-time only.
While you can't use enum for constant known at run-time.
In C++, const is used for both run-time and compile-time constants. In
practice, this works out fine. It its value can only be known at
run-time, it's a run-time constant. If its value is used at
compile-time, it's a compile-time constant. If both of these apply,
it's an error. If neither applies, nobody cares if it's a compile-time
or run-time constant.
(The actual rules in C++ are a bit more complex, less intuitive, and
less useful than that, which is presumably why Walter chose not to copy
the C++ in this case. Still, overloading 'const' for both compile-time
and run-time constants is viable, and more intuitive than the current
situation with 'enum'.)
I have never had troubles with C++ compile/runtime "const" difference,
and don't think it is a problem in C++. With this in mind "enum" is a
great keyword
of choice to express compile-time types, as long as it is forbidden for
run-time constants.
(I hope that example of bearophile is just a bug.)
Thanks.
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