• Temtaime (10/10) Jul 29 2013 I have a long named variable in a struct.
• Namespace (3/13) Jul 29 2013 You can use alias:
• Temtaime (11/11) Jul 29 2013 No, i cannot.
• Namespace (39/50) Jul 29 2013 Oh, that is annoying...
• Namespace (16/16) Jul 29 2013 Alternative:
• Dicebot (4/15) Jul 29 2013 I'd say this is something in between bug and enhancement request.
• bearophile (8/13) Jul 29 2013 You can shorten the outer name with an alias or "remove" it with
• Maxim Fomin (3/10) Jul 29 2013 It doesn't work because alias this does not capture context
• yaz (13/13) Jul 29 2013 You don't need to use dereference operator. Example:
• yaz (2/2) Jul 29 2013 Oh, it doesn't work when accessing member data. Sorry for the

"Temtaime" <temtaime gmail.com> writes:

I have a long named variable in a struct.

For example let's name that longnamedstruct.longnamedmember

I need to use that variable in many places of the code and i 
cannot create the copy of it.

In c++ i can
auto &v = longnamedstruct.longnamedmember;

Now i can use v anywhere.
Why i cannot declare reference in D ? Or can i ?

I can make pointer to that, but it is workaround and it's need to 
use variable dereferencing by * operator.

"Namespace" <rswhite4 googlemail.com> writes:

On Monday, 29 July 2013 at 21:13:54 UTC, Temtaime wrote:
 I have a long named variable in a struct.

 For example let's name that longnamedstruct.longnamedmember

 I need to use that variable in many places of the code and i 
 cannot create the copy of it.

 In c++ i can
 auto &v = longnamedstruct.longnamedmember;

 Now i can use v anywhere.
 Why i cannot declare reference in D ? Or can i ?

 I can make pointer to that, but it is workaround and it's need 
 to use variable dereferencing by * operator.

You can use alias:
alias v = longnamedstruct.longnamedmember;

"Temtaime" <temtaime gmail.com> writes:

No, i cannot.

struct S {
	uint longnamed;
}

void main() {
	S somestruct;

	alias v = somestruct.longnamed;
	writeln(v);
}

Error: need 'this' for 'longnamed' of type 'uint'

Is it a bug ?

"Namespace" <rswhite4 googlemail.com> writes:

On Monday, 29 July 2013 at 21:25:21 UTC, Temtaime wrote:
 No, i cannot.

 struct S {
 	uint longnamed;
 }

 void main() {
 	S somestruct;

 	alias v = somestruct.longnamed;
 	writeln(v);
 }

 Error: need 'this' for 'longnamed' of type 'uint'

 Is it a bug ?

Oh, that is annoying...
Then, make your own reference type:

import std.stdio;

struct S {
	uint longnamed;
}

struct Ref(T) {
public:
	T* ptr;
	
	 disable
	this();
	
	/* disable
	this(this);*/
	
	 disable
	this(typeof(null));
	
	 disable
	void opAssign(ref Ref!T);
	
	this(T* ptr) {
		this.ptr = ptr;
	}
	
	 property
	ref inout(T) get() inout {
		return *this.ptr;
	}
	
	alias get this;
}

void main() {
	S somestruct;

	Ref!uint v = &somestruct.longnamed;
	writeln(v);
}

"Namespace" <rswhite4 googlemail.com> writes:

Alternative:

----
import std.stdio;

struct S {
	uint longnamed;
	
	alias longnamed this;
}

void main() {
	S somestruct;

	alias v = somestruct;
	writeln(v);
	v++;
	writeln(v);
}
----

"Dicebot" <public dicebot.lv> writes:

On Monday, 29 July 2013 at 21:25:21 UTC, Temtaime wrote:
 No, i cannot.

 struct S {
 	uint longnamed;
 }

 void main() {
 	S somestruct;

 	alias v = somestruct.longnamed;
 	writeln(v);
 }

 Error: need 'this' for 'longnamed' of type 'uint'

 Is it a bug ?

I'd say this is something in between bug and enhancement request. 
Nothing explicitly states that alias should work this way but it 
matches concept of alias much better than current behavior.

"bearophile" <bearophileHUGS lycos.com> writes:

Temtaime:

 I have a long named variable in a struct.

 For example let's name that longnamedstruct.longnamedmember

 I need to use that variable in many places of the code and i 
 cannot create the copy of it.

You can shorten the outer name with an alias or "remove" it with 
a with() statement.


 Why i cannot declare reference in D ?

I don't know the reasons. But maybe you can create a little 
struct with just a pointer inside and an alias this to a member 
function that returns a ref.

Bye,
bearophile

"Maxim Fomin" <maxim maxim-fomin.ru> writes:

On Monday, 29 July 2013 at 21:37:30 UTC, bearophile wrote:
 Temtaime:

 Why i cannot declare reference in D ?

 I don't know the reasons. But maybe you can create a little 
 struct with just a pointer inside and an alias this to a member 
 function that returns a ref.

 Bye,
 bearophile

It doesn't work because alias this does not capture context 
pointer like delegate.

"yaz" <yazan.dabain gmail.com> writes:

You don't need to use dereference operator. Example:
http://dpaste.dzfl.pl/d34c23e5

import std.stdio;
struct Foo {
   void answer() {
     writeln("As you wish!");
   }
}

void main() {
   Foo veryVeryLongNamedStruct;
   auto v = &veryVeryLongNamedStruct;
   v.answer();
}

"yaz" <yazan.dabain gmail.com> writes:

Oh, it doesn't work when accessing member data. Sorry for the 
noise.