• Gary Willoughby (10/10) Jun 20 2016 Is there any way to make opApply @nogc? or provide the same
• Mathias Lang (3/13) Jun 20 2016 Can't `opApply` with `auto` return type works since it infers
• Gary Willoughby (3/5) Jun 20 2016 I think the problem is that the delegate which is required by
• Adam D. Ruppe (3/5) Jun 20 2016 make the delegate in opApply scope
• Gary Willoughby (2/7) Jun 20 2016 What effect does this have? and how does it beat the GC?
• Gary Willoughby (4/13) Jun 20 2016 Found the explanation here:
• Gary Willoughby (7/12) Jun 21 2016 I'm still not sure what this achieves. The description on the
• Adam D. Ruppe (6/8) Jun 21 2016 So when you use local variables in a delegate, the compiler
• Gary Willoughby (3/11) Jun 21 2016 Right ok, thanks! It doesn't seem to help though as the compiler
• Marc =?UTF-8?B?U2Now7x0eg==?= (4/6) Jun 22 2016 You probably need to declare the delegate and opApply() itself as
• Gary Willoughby (2/8) Jun 22 2016 That fixed it, thanks all for your help. :)

Gary Willoughby <dev nomad.so> writes:

Is there any way to make opApply  nogc? or provide the same 
foreach functionality without implementing a range interface?

I want to iterate over a piece of memory using a pointer. I 
thought about using opSlice but that doesn't provide information 
for an index in a foreach loop.

auto opSlice()
{
     return this._pointer[0 .. size];
}

Anyone got any ideas?

Mathias Lang <mathias.lang sociomantic.com> writes:

On Monday, 20 June 2016 at 14:08:58 UTC, Gary Willoughby wrote:
 Is there any way to make opApply  nogc? or provide the same 
 foreach functionality without implementing a range interface?

 I want to iterate over a piece of memory using a pointer. I 
 thought about using opSlice but that doesn't provide 
 information for an index in a foreach loop.

 auto opSlice()
 {
     return this._pointer[0 .. size];
 }

 Anyone got any ideas?

Can't `opApply` with `auto` return type works since it infers 
attributes ?

Gary Willoughby <dev nomad.so> writes:

On Monday, 20 June 2016 at 14:34:33 UTC, Mathias Lang wrote:
 Can't `opApply` with `auto` return type works since it infers 
 attributes ?

I think the problem is that the delegate which is required by 
opApply is allocated using the GC.

Adam D. Ruppe <destructionator gmail.com> writes:

On Monday, 20 June 2016 at 15:13:53 UTC, Gary Willoughby wrote:
 I think the problem is that the delegate which is required by 
 opApply is allocated using the GC.

make the delegate in opApply scope

int opApply(scope int delegate(whatever) dg)

Gary Willoughby <dev nomad.so> writes:

On Monday, 20 June 2016 at 15:27:32 UTC, Adam D. Ruppe wrote:
 On Monday, 20 June 2016 at 15:13:53 UTC, Gary Willoughby wrote:
 I think the problem is that the delegate which is required by 
 opApply is allocated using the GC.

 make the delegate in opApply scope

 int opApply(scope int delegate(whatever) dg)

What effect does this have? and how does it beat the GC?

Gary Willoughby <dev nomad.so> writes:

On Monday, 20 June 2016 at 15:47:44 UTC, Gary Willoughby wrote:
 On Monday, 20 June 2016 at 15:27:32 UTC, Adam D. Ruppe wrote:
 On Monday, 20 June 2016 at 15:13:53 UTC, Gary Willoughby wrote:
 I think the problem is that the delegate which is required by 
 opApply is allocated using the GC.

 make the delegate in opApply scope

 int opApply(scope int delegate(whatever) dg)

 What effect does this have? and how does it beat the GC?

Found the explanation here:

http://stackoverflow.com/questions/4711309/meaning-of-scope-in-d-for-a-parameter

I give it a go. Thanks.

Gary Willoughby <dev nomad.so> writes:

On Monday, 20 June 2016 at 15:27:32 UTC, Adam D. Ruppe wrote:
 On Monday, 20 June 2016 at 15:13:53 UTC, Gary Willoughby wrote:
 I think the problem is that the delegate which is required by 
 opApply is allocated using the GC.

 make the delegate in opApply scope

 int opApply(scope int delegate(whatever) dg)

I'm still not sure what this achieves. The description on the 
stackoverflow question reads: "And when the compiler sees this on 
delegates, it will avoid allocating a closure when taking the 
address of a local function. This is essential in opApply loops."

I have no idea what that means. Can anyone shed more light on 
this, please?

Adam D. Ruppe <destructionator gmail.com> writes:

On Tuesday, 21 June 2016 at 12:48:04 UTC, Gary Willoughby wrote:
 I have no idea what that means. Can anyone shed more light on 
 this, please?

So when you use local variables in a delegate, the compiler 
usually makes a copy of them just in case the delegate gets saved 
for later.

When you mark it scope, you promise that you won't save it for 
later, so the compiler skips making the copy.

Gary Willoughby <dev nomad.so> writes:

On Tuesday, 21 June 2016 at 12:53:11 UTC, Adam D. Ruppe wrote:
 On Tuesday, 21 June 2016 at 12:48:04 UTC, Gary Willoughby wrote:
 I have no idea what that means. Can anyone shed more light on 
 this, please?

 So when you use local variables in a delegate, the compiler 
 usually makes a copy of them just in case the delegate gets 
 saved for later.

 When you mark it scope, you promise that you won't save it for 
 later, so the compiler skips making the copy.

Right ok, thanks! It doesn't seem to help though as the compiler 
complains about it being not  nogc.

Marc =?UTF-8?B?U2Now7x0eg==?= <schuetzm gmx.net> writes:

On Tuesday, 21 June 2016 at 19:21:01 UTC, Gary Willoughby wrote:
 Right ok, thanks! It doesn't seem to help though as the 
 compiler complains about it being not  nogc.

You probably need to declare the delegate and opApply() itself as 
 nogc, too:

int opApply(scope int delegate(int)  nogc dg)  nogc { }

Gary Willoughby <dev nomad.so> writes:

On Wednesday, 22 June 2016 at 13:36:54 UTC, Marc Schütz wrote:
 On Tuesday, 21 June 2016 at 19:21:01 UTC, Gary Willoughby wrote:
 Right ok, thanks! It doesn't seem to help though as the 
 compiler complains about it being not  nogc.

 You probably need to declare the delegate and opApply() itself 
 as  nogc, too:

 int opApply(scope int delegate(int)  nogc dg)  nogc { }

That fixed it, thanks all for your help. :)