• Puming (24/24) Jun 30 2014 Hi,
• Puming (2/26) Jun 30 2014
• =?UTF-8?B?QWxpIMOHZWhyZWxp?= (22/49) Jun 30 2014 I don't understand your question but I wanted to help others by making
• Puming (31/82) Jun 30 2014 Thanks, This code works and my question is that is this a good
• bearophile (6/10) Jul 01 2014 A "ref" is equivalent to a pointer that can't be null, so
• Puming (3/13) Jul 01 2014 Thanks for the clarification. Now I can safely assume ref is
• =?UTF-8?B?QWxpIMOHZWhyZWxp?= (22/24) Jul 01 2014 I don't understand that part. :) The following is the same program with
• Puming (4/31) Jul 01 2014 Wow, I've tested with some other code and pointer did not work,

"Puming" <zhaopuming gmail.com> writes:

Hi,

I have a struct and want to extends its methods, like:

```d
struct Server
{
   string name;
   string ip;
   int port;
   string user;
}
```

extension method here:

```d
string prompt(ref in Server server)
{
    return server.user ~ " " ~ server.ip ~ ":" ~ server.port;
}

```

and call it with UFSC:

```d
string p = server.prompt;
```

is this the correct way to use struct and UFCS? it does not seem 
to copy there.

"Puming" <zhaopuming gmail.com> writes:

On Tuesday, 1 July 2014 at 05:09:49 UTC, Puming wrote:
 Hi,

 I have a struct and want to extends its methods, like:

 ```d
 struct Server
 {
   string name;
   string ip;
   int port;
   string user;
 }
 ```

 extension method here:

 ```d
 string prompt(ref in Server server)
 {
    return server.user ~ " " ~ server.ip ~ ":" ~ server.port;
 }

 ```

should be `server.port.to!int`;
 and call it with UFSC:

 ```d
 string p = server.prompt;
 ```

 is this the correct way to use struct and UFCS? it does not 
 seem to copy there.

=?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:

On 06/30/2014 10:11 PM, Puming wrote:

 On Tuesday, 1 July 2014 at 05:09:49 UTC, Puming wrote:
 Hi,

 I have a struct and want to extends its methods, like:

 ```d
 struct Server
 {
   string name;
   string ip;
   int port;
   string user;
 }
 ```

 extension method here:

 ```d
 string prompt(ref in Server server)
 {
    return server.user ~ " " ~ server.ip ~ ":" ~ server.port;
 }

 ```

 should be `server.port.to!int`;

I think it should actually be server.port.to!string;

 is this the correct way to use struct and UFCS? it does not seem to
 copy there.


I don't understand your question but I wanted to help others by making 
complete code from your messages:

import std.conv;

struct Server
{
     string name;
     string ip;
     int port;
     string user;
}

string prompt(ref in Server server)
{
     return server.user ~ " " ~ server.ip ~ ":" ~ server.port.to!string;
}

void main()
{
     auto server = Server("bzzt", "192.168.0.1", 80, "nobody");
     string p = server.prompt;
}

Ali

"Puming" <zhaopuming gmail.com> writes:

On Tuesday, 1 July 2014 at 05:26:47 UTC, Ali Çehreli wrote:
 On 06/30/2014 10:11 PM, Puming wrote:

 On Tuesday, 1 July 2014 at 05:09:49 UTC, Puming wrote:
 Hi,

 I have a struct and want to extends its methods, like:

 ```d
 struct Server
 {
   string name;
   string ip;
   int port;
   string user;
 }
 ```

 extension method here:

 ```d
 string prompt(ref in Server server)
 {
    return server.user ~ " " ~ server.ip ~ ":" ~ server.port;
 }

 ```

 should be `server.port.to!int`;

 I think it should actually be server.port.to!string;

 is this the correct way to use struct and UFCS? it does not


 seem to
 copy there.


 I don't understand your question but I wanted to help others by 
 making complete code from your messages:

 import std.conv;

 struct Server
 {
     string name;
     string ip;
     int port;
     string user;
 }

 string prompt(ref in Server server)
 {
     return server.user ~ " " ~ server.ip ~ ":" ~ 
 server.port.to!string;
 }

 void main()
 {
     auto server = Server("bzzt", "192.168.0.1", 80, "nobody");
     string p = server.prompt;
 }

 Ali

Thanks, This code works and my question is that is this a good 
practice to use `ref in` with structs instead of traditional 
pointer syntax (which does not play well with UFCS though) ? Is 
there any perfomance implications with `ref in`? I tried that it 
does not seem to copy the parameter value, which is good for me:


```d


import std.stdio;

struct Server
{
	string name;
}

string prompt(ref in Server server)
{
	__server.name = "new name";
	return server.name ~ ">";
}

Server __server;

void main()
{
	__server.name = "old_name";

	writeln(__server.prompt);
}
```

which prints

```
newname>
```

meaning the `return server.name ~ ">"` code in promt is using a 
reference of __server instead of copying the value.

"bearophile" <bearophileHUGS lycos.com> writes:

Puming:

 is this a good practice to use `ref in` with structs instead of 
 traditional pointer syntax (which does not play well with UFCS 
 though) ? Is there any perfomance implications with `ref in`? I 
 tried that it does not seem to copy the parameter value,

A "ref" is equivalent to a pointer that can't be null, so 
performance is the same as using a pointer (so it's good for 
larger structs, but not good if your struct is tiny).

Bye,
bearophile

"Puming" <zhaopuming gmail.com> writes:

On Tuesday, 1 July 2014 at 07:53:27 UTC, bearophile wrote:
 Puming:

 is this a good practice to use `ref in` with structs instead 
 of traditional pointer syntax (which does not play well with 
 UFCS though) ? Is there any perfomance implications with `ref 
 in`? I tried that it does not seem to copy the parameter value,

 A "ref" is equivalent to a pointer that can't be null, so 
 performance is the same as using a pointer (so it's good for 
 larger structs, but not good if your struct is tiny).

 Bye,
 bearophile

Thanks for the clarification. Now I can safely assume ref is 
better than pointer here because it plays nicely with UFCS.

=?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:

On 07/01/2014 03:21 AM, Puming wrote:

 I can safely assume ref is better than pointer here

I agree.

 because it plays nicely with UFCS.

I don't understand that part. :) The following is the same program with 
just two differences: prompt() takes a pointer and 'server' is a pointer.

import std.conv;

struct Server
{
     string name;
     string ip;
     int port;
     string user;
}

string prompt(Server * server)
{
     return server.user ~ " " ~ server.ip ~ ":" ~ server.port.to!string;
}

void main()
{
     auto server = new Server("bzzt", "192.168.0.1", 80, "nobody");
     string p = server.prompt;
}

Ali

"Puming" <zhaopuming gmail.com> writes:

On Tuesday, 1 July 2014 at 13:53:12 UTC, Ali Çehreli wrote:
 On 07/01/2014 03:21 AM, Puming wrote:

 I can safely assume ref is better than pointer here

 I agree.

 because it plays nicely with UFCS.

 I don't understand that part. :) The following is the same 
 program with just two differences: prompt() takes a pointer and 
 'server' is a pointer.

 import std.conv;

 struct Server
 {
     string name;
     string ip;
     int port;
     string user;
 }

 string prompt(Server * server)
 {
     return server.user ~ " " ~ server.ip ~ ":" ~ 
 server.port.to!string;
 }

 void main()
 {
     auto server = new Server("bzzt", "192.168.0.1", 80, 
 "nobody");
     string p = server.prompt;
 }

 Ali

Wow, I've tested with some other code and pointer did not work, 
maybe I got something else wrong. Anyway, it's nice to know 
pointers also works with UFCS :-)