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);

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?

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 .

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 :)

On Fri, 26 Apr 2013 09:31:54 +0200, Trey Brisbane wrote:

> 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 might want to look at std.windows.charset. You'll find the following functions:

	const(char)* toMBSz(in char[] s, uint codePage = 0)
	string fromMBSz(immutable(char)* s, int codePage = 0)

These might work for you or you may be able to expand on them.

On 04/26/2013 01:49 AM, anonymous wrote:

> On Friday, 26 April 2013 at 07:31:57 UTC, Trey Brisbane wrote:

> UFCS should be explained in the online language documentation,
> but if it's in there I can't find it.

Me neither. I wonder where in the language syntax a "function call" lives...

UFCS does not require more than what you have already said but it looks like I had managed to fill up more space than a couple of paragraphs: :)

  http://ddili.org/ders/d.en/ufcs.html

Ali