Re: __dtor vs __xdtor

[Marco Leise via Digitalmars-d-learn]

Am Fri, 11 Aug 2017 17:10:14 +
schrieb bitwise :

> Ok thanks.
> 
> I don't understand why you would ever want to call __dtor 
> then...is it possible to have only __dtor without also having 
> __xdtor? Like, if I want to call a struct's destructor, do I have 
> to check for both, or can I just always check for, and call 
> __xdtor?

I think it was simply that all the special methods needed a
symbol name, so this() was called __ctor and ~this() was
called __dtor. It was never supposed to cover field
destruction, mixed in destructors or inheritance in classes.
User code was not expected to call these directly anyways.
Not very long ago __xdtor and __xpostblit were introduced
that wrap up the entire finalization and copy operation.
__dtor will remain as the 1:1 representation of the ~this()
method.

-- 
Marco

Re: __dtor vs __xdtor

[bitwise via Digitalmars-d-learn]

On Friday, 11 August 2017 at 17:20:18 UTC, HyperParrow wrote:

[...]
I made a mistake but it's not about i, which is a global.
I meant "other.__dtor." just before the last assert.
This doesn't change the results.


hmm...indeed ;)

On Friday, 11 August 2017 at 17:24:17 UTC, HyperParrow wrote:

[...]

is it possible to have only __dtor without also having 
__xdtor? Like, if I want to call a struct's destructor, do I 
have to check for both, or can I just always check for, and 
call __xdtor?


Always use __xdtor unless you know there's no other destructor 
to call.


Ok cool, thanks.

Re: __dtor vs __xdtor

[HyperParrow via Digitalmars-d-learn]

On Friday, 11 August 2017 at 17:10:14 UTC, bitwise wrote:

On Friday, 11 August 2017 at 17:02:20 UTC, HyperParrow wrote:

On Friday, 11 August 2017 at 16:53:02 UTC, bitwise wrote:

What do they do?
What's the difference?

Thanks


__xdtor() also calls the __dtor() that are mixed with template 
mixins while __dtor() only call the __dtor() that matches to 
the normal ~this(){}


Ok thanks.

I don't understand why you would ever want to call __dtor 
then...


Indeed. And there's also another one for the field called 
__fieldDtor.


is it possible to have only __dtor without also having __xdtor? 
Like, if I want to call a struct's destructor, do I have to 
check for both, or can I just always check for, and call 
__xdtor?


Always use __xdtor unless you know there's no other destructor to 
call.
Actually these functions are an implementation details and should 
be only used for low level things like custom memory handling.


You can look at core/lifetime.d to see how it's used by the d 
runtime.

Re: __dtor vs __xdtor

[HyperParrow via Digitalmars-d-learn]

On Friday, 11 August 2017 at 17:12:22 UTC, bitwise wrote:

On Friday, 11 August 2017 at 17:06:40 UTC, HyperParrow wrote:
[...]

int i;
struct Foo
{
template ToMix(){ ~this(){i;}}
~this(){++i;}
mixin ToMix;
}

void main()
{
Foo* foo = new Foo;
foo.__xdtor;
assert(i==3);
Foo* other = new Foo;
foo.__dtor;
assert(i==4); // and not 6 ;)
}
=


I think you mean assert(i == 1) for the second one, right?


I made a mistake but it's not about i, which is a global.
I meant "other.__dtor." just before the last assert.
This doesn't change the results.

Re: __dtor vs __xdtor

[bitwise via Digitalmars-d-learn]

On Friday, 11 August 2017 at 17:06:40 UTC, HyperParrow wrote:
[...]

int i;
struct Foo
{
template ToMix(){ ~this(){i;}}
~this(){++i;}
mixin ToMix;
}

void main()
{
Foo* foo = new Foo;
foo.__xdtor;
assert(i==3);
Foo* other = new Foo;
foo.__dtor;
assert(i==4); // and not 6 ;)
}
=


I think you mean assert(i == 1) for the second one, right?

Re: __dtor vs __xdtor

[bitwise via Digitalmars-d-learn]

On Friday, 11 August 2017 at 17:02:20 UTC, HyperParrow wrote:

On Friday, 11 August 2017 at 16:53:02 UTC, bitwise wrote:

What do they do?
What's the difference?

Thanks


__xdtor() also calls the __dtor() that are mixed with template 
mixins while __dtor() only call the __dtor() that matches to 
the normal ~this(){}


Ok thanks.

I don't understand why you would ever want to call __dtor 
then...is it possible to have only __dtor without also having 
__xdtor? Like, if I want to call a struct's destructor, do I have 
to check for both, or can I just always check for, and call 
__xdtor?

Re: __dtor vs __xdtor

[HyperParrow via Digitalmars-d-learn]

On Friday, 11 August 2017 at 17:02:20 UTC, HyperParrow wrote:

On Friday, 11 August 2017 at 16:53:02 UTC, bitwise wrote:

What do they do?
What's the difference?

Thanks


__xdtor() also calls the __dtor() that are mixed with template 
mixins while __dtor() only call the __dtor() that matches to 
the normal ~this(){}


Nice example that speaks by itself:

=
int i;
struct Foo
{
template ToMix(){ ~this(){i;}}
~this(){++i;}
mixin ToMix;
}

void main()
{
Foo* foo = new Foo;
foo.__xdtor;
assert(i==3);
Foo* other = new Foo;
foo.__dtor;
assert(i==4); // and not 6 ;)
}
=

Re: __dtor vs __xdtor

[HyperParrow via Digitalmars-d-learn]

On Friday, 11 August 2017 at 16:53:02 UTC, bitwise wrote:

What do they do?
What's the difference?

Thanks


__xdtor() also calls the __dtor() that are mixed with template 
mixins while __dtor() only call the __dtor() that matches to the 
normal ~this(){}

__dtor vs __xdtor

[bitwise via Digitalmars-d-learn]

What do they do?
What's the difference?

Thanks