On Thursday, 10 July 2014 at 17:01:45 UTC, Jane Doe wrote:
One thing that bothers me quite a bit is that char's do not
have length. This makes it difficult in templates that can take
either strings or chars.
While one can write a template that returns the length of a
string or char, I would imagine that this could be implemented
in the compiler more efficiently?
char.length always returns 1.
Similarly, it would be nice to be able to use [] on chars.
char[x] returns char.
Example:
auto last(T)(T s) { return s[s.length-1]; }
void main()
{
writeln(last("asdf"));
writeln(last('c')); // fails!! But surely this should
work!
}
http://dpaste.dzfl.pl/cba5a635d08e
Error: s must be an array or pointer type, not char
Error: no property 'length' for type 'char'
Basically, I see no reason why char's can't be more confluent
with strings, at least on the surface. I would reduce code
bloat/specialization for no real reason.
If the compile knows a type is a char then char.length = 1 and
char[x] = char. Shouldn't be hard or cause any problems?
Would cause unexpected behavior / hard to track errors on typos.
If you want, you can do it yourself with UFCS:
import std.traits;
size_t length(C)(C c) if(isSomeChar!C)
{
return 1;
}
unittest
{
assert('a'.length == 1);
}
Not sure if you can do the same for opIndex(S)(S s)
if(isSomeString!C) , probably not.
But you can do:
auto at(T)(T t, I index) if(isIntegral!T && (isSomeChar!T ||
isSomeString!T))
{
static if(isSomeChar!T)
{
assert(index == 0,
"Non-zero index makes no sense for a single
character);
return t;
}
else
{
return t[index];
}
}
unittest
{
assert("qwe".at(1) == 'w'.at(0));
}
(Note that I didn't test any of those, it may need modification)
That said, it's much better practice/safer/more maintainable use
static if
individually in any code that needs to treat characters and
strings the same
way, since they are _not_ the same. Static typing exists for a
reason.
