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digitalmars.D - How do I do placement delete in D?

reply "Craig Black" <craigblack2 cox.net> writes:
I know emplace is used to do placement new.  What is the equivalent 
placement delete?

-Craig
Dec 14 2010
parent reply "Steven Schveighoffer" <schveiguy yahoo.com> writes:
On Tue, 14 Dec 2010 15:18:32 -0500, Craig Black <craigblack2 cox.net>  
wrote:


 I know emplace is used to do placement new.  What is the equivalent  
 placement delete?


x = emplace(yourAllocationFunction!T());

...

clear(x);
yourDeallocationFunction(x); // if necessary.  For instance, stack data  
doesn't need to be deallocated

-Steve
Dec 14 2010
parent reply "Craig Black" <craigblack2 cox.net> writes:
"Steven Schveighoffer" <schveiguy yahoo.com> wrote in message 
news:op.vnpz6ob6eav7ka steve-laptop...

 On Tue, 14 Dec 2010 15:18:32 -0500, Craig Black <craigblack2 cox.net> 
 wrote:


 I know emplace is used to do placement new.  What is the equivalent 
 placement delete?


 x = emplace(yourAllocationFunction!T());

 ...

 clear(x);
 yourDeallocationFunction(x); // if necessary.  For instance, stack data 
 doesn't need to be deallocated

 -Steve


Is there a way to explicitly invoke a struct destructor without doing an 
explicit delete?

-Craig
Dec 14 2010
parent reply "Steven Schveighoffer" <schveiguy yahoo.com> writes:
On Tue, 14 Dec 2010 15:33:26 -0500, Craig Black <craigblack2 cox.net>  
wrote:


 "Steven Schveighoffer" <schveiguy yahoo.com> wrote in message  
 news:op.vnpz6ob6eav7ka steve-laptop...

 On Tue, 14 Dec 2010 15:18:32 -0500, Craig Black <craigblack2 cox.net>  
 wrote:


 I know emplace is used to do placement new.  What is the equivalent  
 placement delete?


 x = emplace(yourAllocationFunction!T());

 ...

 clear(x);
 yourDeallocationFunction(x); // if necessary.  For instance, stack data  
 doesn't need to be deallocated

 -Steve


 Is there a way to explicitly invoke a struct destructor without doing an  
 explicit delete?


Not sure what you mean.  All clear is going to do is invoke the  
destructor, so I don't know what else you need?

-Steve
Dec 14 2010
next sibling parent reply "Craig Black" <craigblack2 cox.net> writes:
Thanks Steve.  clear seems to be calling the destructor twice.  Is this 
intentional?

-Craig
Dec 14 2010
next sibling parent reply "Steven Schveighoffer" <schveiguy yahoo.com> writes:
On Tue, 14 Dec 2010 16:05:14 -0500, Craig Black <craigblack2 cox.net>  
wrote:


 Thanks Steve.  clear seems to be calling the destructor twice.  Is this  
 intentional?


No.  Can you file a bug?

-Steve
Dec 14 2010
next sibling parent "Craig Black" <craigblack2 cox.net> writes:
 No.  Can you file a bug?
 
 -Steve


done
Dec 14 2010
prev sibling parent reply "Craig Black" <craigblack2 cox.net> writes:
Arg!  Someone removed my bug report and assumed I was wrong about it without 
even checking into it.  Why do I even try to help the D community?
Dec 14 2010
next sibling parent reply Andrei Alexandrescu <SeeWebsiteForEmail erdani.org> writes:
On 12/14/10 5:09 PM, Craig Black wrote:

 Arg! Someone removed my bug report and assumed I was wrong about it
 without even checking into it. Why do I even try to help the D community?


The bug report stands, thanks for clarifying it.

Andrei
Dec 14 2010
parent "Craig Black" <craigblack2 cox.net> writes:
"Andrei Alexandrescu" <SeeWebsiteForEmail erdani.org> wrote in message 
news:ie8vpc$2gbg$1 digitalmars.com...

 On 12/14/10 5:09 PM, Craig Black wrote:

 Arg! Someone removed my bug report and assumed I was wrong about it
 without even checking into it. Why do I even try to help the D community?


 The bug report stands, thanks for clarifying it.

 Andrei


Thanks!
Dec 14 2010
prev sibling parent "Steven Schveighoffer" <schveiguy yahoo.com> writes:
On Tue, 14 Dec 2010 18:09:44 -0500, Craig Black <craigblack2 cox.net>  
wrote:


 Arg!  Someone removed my bug report and assumed I was wrong about it  
 without even checking into it.  Why do I even try to help the D  
 community?


Nobody removed your report, I'm not sure why you think that.  I hope you  
don't stop trying to improve D, we need everyone's support who is willing  
to give it.

-Steve
Dec 15 2010
prev sibling parent reply Stanislav Blinov <blinov loniir.ru> writes:
15.12.2010 0:05, Craig Black пишет:

 Thanks Steve.  clear seems to be calling the destructor twice.  Is 
 this intentional?

 -Craig


AFAIR, it's not 'clear()' that calls destructor twice. Some time ago, 
there has been discussion on how to properly implement clear(). Initial 
implementation calls dtor, then calls default ctor to leave the object 
in a meaningful state for the GC to consume. Therefore, when object is 
being collected, dtor gets called for a second time. The discussion 
ended on the proposal of nullifying objec't vtbl instead of calling 
default ctor, which will obviate the need of a second dtor call, but I 
think this is not currently implemented.
Dec 15 2010
parent "Steven Schveighoffer" <schveiguy yahoo.com> writes:
On Wed, 15 Dec 2010 12:46:34 -0500, Stanislav Blinov <blinov loniir.ru>  
wrote:


 15.12.2010 0:05, Craig Black пишет:

 Thanks Steve.  clear seems to be calling the destructor twice.  Is this  
 intentional?

 -Craig


 AFAIR, it's not 'clear()' that calls destructor twice. Some time ago,  
 there has been discussion on how to properly implement clear(). Initial  
 implementation calls dtor, then calls default ctor to leave the object  
 in a meaningful state for the GC to consume. Therefore, when object is  
 being collected, dtor gets called for a second time. The discussion  
 ended on the proposal of nullifying objec't vtbl instead of calling  
 default ctor, which will obviate the need of a second dtor call, but I  
 think this is not currently implemented.


No, the issue is different.  Struct dtors are not called when GC memory is  
collected.  I found the issue.  I just checked in a fix:

http://www.dsource.org/projects/druntime/changeset/451

-Steve
Dec 15 2010
prev sibling parent "Craig Black" <craigblack2 cox.net> writes:
About the destructor being called twice, perhaps clear is passing by value 
rather than by reference?  If so, is this desirable?

-Craig
Dec 14 2010