Char literals

[Eldar Insafutdinov]

Bill Baxter Wrote:

> On Fri, Nov 6, 2009 at 3:24 AM, Eldar Insafutdinov
> <e.insafutdinov at gmail.com> wrote:
> > I've just written a simple replicate function (the one from std.range does not work in CTFE):
> > T[] replicate(T)(int n, T value)
> > {
> >    T[] ret;
> >    if (n > 0)
> >    {
> >        for(int i = 0; i < n; i++)
> >            ret ~= value;
> >    }
> >    return ret;
> > }
> > it's not the best implementation, but that's not the thing I want to say today. When I call it
> >
> > string str = replicate(5, 'a');
> >
> > I get
> >
> > moc.d(370): Error: cannot implicitly convert expression (replicate(5,',')) of type char[] to string
> >
> > That means that char literals are "char", but not "immutable(char)". I remember the whole conversation about array literals, but char literals are closer to those of the string. What's the reasoning behind leaving them as mutable char?
> 
> In Phobos they use std.contracts.assumeUnique to turn char[] to string
> at the end of string processing functions.  It's actually just a cast
> to immutable(char)[].  But the idea is you're asserting that you know
> the char[] data is not referenced by anyone else (your reference is
> unique) so it's safe to make it immutable.  So it documents the intent
> better than a straight cast.  It's also better because if you later
> change the underlying type say from char[] to dchar[], assumeUnique
> will still do the right thing (become a cast to immutable(dchar)[]),
> but cast(string) would silently become bogus.
> 
> --bb

Yes you are right, I used cast(string) eventually and made it non-template. There were other bugs that are specific to CTFE that I could not track down though.