• Xiaoxi (4/4) Jun 20 2015 When passing a struct by value:
• =?UTF-8?B?QWxpIMOHZWhyZWxp?= (36/40) Jun 20 2015 Can you show with an example please. I don't see either of those called
• Xiaoxi (43/50) Jun 21 2015 Dear Ali,
• Namespace (8/11) Jun 21 2015 Change 'foo' to this:

"Xiaoxi" <xiaoxi 163.com> writes:

When passing a struct by value:

Is there any way to trick the compiler to elide unnecessary 
post-blit & dtor pair?

Maybe using an union, somehow?

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

On 06/20/2015 02:09 PM, Xiaoxi wrote:
 When passing a struct by value:

 Is there any way to trick the compiler to elide unnecessary post-blit &
 dtor pair?

 Maybe using an union, somehow?

Can you show with an example please. I don't see either of those called 
for the following program:

import std.stdio;

struct S
{
     this(int)
     {
         writeln(__FUNCTION__);
     }

     this(this)
     {
         writeln(__FUNCTION__);
     }

     ~this()
     {
         writeln(__FUNCTION__);
     }
}

S foo()
{
     auto s = S(42);
     return s;
}

void main()
{
     writeln("before");
     auto s = foo();
     writeln("after");
}

The output:

before
deneme.S.this
after
deneme.S.~this

Ali

"Xiaoxi" <xiaoxi 163.com> writes:

On Saturday, 20 June 2015 at 22:44:17 UTC, Ali Çehreli wrote:
 On 06/20/2015 02:09 PM, Xiaoxi wrote:
 The output:

 before
 deneme.S.this
 after
 deneme.S.~this

 Ali

Dear Ali,

thank you for helping! Problem happens when passing by value as 
in param.

DMD32 D Compiler v2.067.0
deneme.S.this
before
deneme.S.__postblit
deneme.S.__postblit
deneme.S.~this
deneme.S.~this
after
deneme.S.~this

import std.stdio;

struct S
{
     int val;
     this(int par)
     {
         val = par;
         writeln(__FUNCTION__);
     }

     this(this)
     {
         writeln(__FUNCTION__);
     }

     ~this()
     {
         writeln(__FUNCTION__);
     }
}

S foo(S s)
{
     s.val+=1;
     return s;
}

void main()
{
     auto s = S(42);
     writeln("before");
     foo(s);
     writeln("after");
}

"Namespace" <rswhite4 gmail.com> writes:

 Dear Ali,

 thank you for helping! Problem happens when passing by value as 
 in param.

Change 'foo' to this:
----
ref S foo(ref S s)
{
     s.val+=1;
     return s;
}
----