How/why can toStringz() and toUTFz() be used as properties?

[Trey Brisbane]

On Friday, 26 April 2013 at 08:49:10 UTC, anonymous wrote:
> On Friday, 26 April 2013 at 07:31:57 UTC, Trey Brisbane wrote:
>> Hey all,
>>
>> Can someone please explain to me how and why it is that 
>> toStringz() and toUTFz() can be used in the following way?
>>
>> string a = "123";
>> auto b = a.toStringz;
>> auto c = a.toUTFz;
>>
>> Also, how is it that they can even be called as if they were 
>> class methods? That is:
>>
>> string a = "123";
>> auto b = a.toStringz(); // <-- Note I've added parentheses
>> auto c = a.toUTFz();
>>
>> As opposed to being limited to:
>>
>> string a = "123";
>> auto b = toStringz(a);
>> auto c = toUTFz(a);
>
> There's two things at work here:
>
> a) Universal Function Call Syntax (UFCS). That basically means 
> that you can call a free function via method/property-like dot 
> syntax. The first argument to the function goes before the dot. 
> UFCS should be explained in the online language documentation, 
> but if it's in there I can't find it.
> So, with UFCS you get from  toStringz(a)  to  a.toStringz() .
>
> b) Empty parentheses are optional. -- Unless you compile with 
> the -property flag. There has been some discussion about the 
> future of the feature. Optional empty parentheses and/or the 
> -property flag may go away in the future.
> That gets you from  a.toString()  to  a.toString .
>
>> I need to understand this, as I wish to write a function 
>> toWinStr() that can be used in the same way which will accept 
>> any string type, and, based on something like version(Unicode) 
>> and const-ness, output a WinAPI LPSTR, LPCSTR, LPWSTR or 
>> LPCWSTR as appropriate.
>> Is such a thing possible?
>
> You just write your function so that  toWinStr(stuff)  works. 
> UFCS and optional empty parentheses then enable  stuff.toWinStr 
> .

Ahhh ok, thanks for explaining :)