Should .idup simply do nothing for arrays that are alreadyimmutable?

[BCS]

Hello Simen,

> On Fri, 08 Jan 2010 22:28:32 +0100, BCS <none at anon.com> wrote:
> 
>> Hello dsimcha,
>> 
>>> import std.stdio;
>>> void main() {
>>> immutable foo = "FOO";
>>> immutable bar = foo.idup;
>>> writeln(foo.ptr, '\t', bar.ptr);
>>> }
>>> Output:
>>> 42C090  97AE40
>>> Should we define .idup on an already-immutable array to simply do
>>> nothing?  It seems that there is never any good reason to copy an
>>> immutable array, and it would avoid the need to either needlessly
>>> copy
>>> an array or explicitly check for immutability in metaprogramming
>>> situations.
>> I can think of one case where I would want to force the copy: In
>> template code where I've got a mutable or immutable object/array and
>> I
>> want to make a modified immutable version of it. - idup it
>> - modify it via casting away the immutability
>> - never change it again
> Don't do this. It's undefined, it's ugly, and it's wrong, and the
> language definitely should in no way aid such behavior.
> 

I didn't say I thought it was a /good/ idea. :)