Idea: Introduce zero-terminated string specifier

[Piotr Szturmaj]

Johannes Pfau wrote:
>> struct CString(T)
>>       if (isSomeChar!T)
>> {
>>       T* str;
>> }
>>
>> @property
>> auto cstring(S : T*, T)(S str)
>>       if (isSomeChar!T)
>> {
>>       return CString!T(str);
>> }
>>
>> string test = "abc";
>> immutable(char)* p = test.ptr;
>>
>> writefln("%s", p.cstring); // prints "abc"
>>
>> Here the char pointer type is "annotated" as null terminated string
>> and writefln can use this information.
>
> If CString implemented a toString method (probably the variant taking a
> sink delegate), this would already work.

I reworked this example to form a forward range:

http://dpaste.dzfl.pl/7ab1eeec

The major advantage over "%zs" is that it could be used anywhere, not 
only with writef().

For example C binding writers may change:

extern(C) char* getstr();

to

extern(C) cstring getstr();

so the string may be immediately used with writef();

 > I'm not sure about performance
 > though: Isn't writing out bigger buffers a lot faster than writing
 > single chars? You could print every char individually, but wouldn't a
 > p[0 .. strlen(p)] usually be faster?

I think it internally prints single characters anyway. At least it must 
test each character if it's not zero valued. strlen() does that.