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digitalmars.D.bugs - [Issue 11616] New: Introduce virtual keyword and remove virtual-by-default

reply d-bugmail puremagic.com writes:
https://d.puremagic.com/issues/show_bug.cgi?id=11616

           Summary: Introduce virtual keyword and remove
                    virtual-by-default
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Keywords: preapproved
          Severity: enhancement
          Priority: P2
         Component: DMD
        AssignedTo: yebblies gmail.com
        ReportedBy: yebblies gmail.com



Thread with discussion and Walter-approval:

http://forum.dlang.org/thread/yzsqwejxqlnzryhrkfuq forum.dlang.org?page=28#post-koqkhc:244nn:241:40digitalmars.com

1. Add warning for not marking a virtual method with 'virtual'
2. Deprecate not marking a virtual method with 'virtual'
3. Make it an error to not mark virtual methods with 'virtual'

At this point, all methods are marked with either 'virtual', 'final',
'abstract', or 'override' or are implicitly final. (eg template methods,
constructors)

4. Do not require 'final' to mark a function as final. (optional)

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next sibling parent d-bugmail puremagic.com writes:
https://d.puremagic.com/issues/show_bug.cgi?id=11616


Manu <turkeyman gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |turkeyman gmail.com





 Thread with discussion and Walter-approval:
 
 http://forum.dlang.org/thread/yzsqwejxqlnzryhrkfuq forum.dlang.org?page=28#post-koqkhc:244nn:241:40digitalmars.com
 
 1. Add warning for not marking a virtual method with 'virtual'
 2. Deprecate not marking a virtual method with 'virtual'
 3. Make it an error to not mark virtual methods with 'virtual'
 
 At this point, all methods are marked with either 'virtual', 'final',
 'abstract', or 'override' or are implicitly final. (eg template methods,
 constructors)
 
 4. Do not require 'final' to mark a function as final. (optional)


Since I already started writing this, I may as well paste it here:
http://wiki.dlang.org/DIP51
It can be updated if details emerge.

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prev sibling next sibling parent d-bugmail puremagic.com writes:
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 Thread with discussion and Walter-approval:
 
 http://forum.dlang.org/thread/yzsqwejxqlnzryhrkfuq forum.dlang.org?page=28#post-koqkhc:244nn:241:40digitalmars.com
 
 1. Add warning for not marking a virtual method with 'virtual'
 2. Deprecate not marking a virtual method with 'virtual'
 3. Make it an error to not mark virtual methods with 'virtual'
 
 At this point, all methods are marked with either 'virtual', 'final',
 'abstract', or 'override' or are implicitly final. (eg template methods,
 constructors)
 
 4. Do not require 'final' to mark a function as final. (optional)


 
 Since I already started writing this, I may as well paste it here:
 http://wiki.dlang.org/DIP51
 It can be updated if details emerge.


I updated it.  The warning goes on the introducing method, not on the
overriding one.  This forces all methods to be correctly annotated, even if
there are no derived classes.

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 Thread with discussion and Walter-approval:
 
 http://forum.dlang.org/thread/yzsqwejxqlnzryhrkfuq forum.dlang.org?page=28#post-koqkhc:244nn:241:40digitalmars.com
 
 1. Add warning for not marking a virtual method with 'virtual'
 2. Deprecate not marking a virtual method with 'virtual'
 3. Make it an error to not mark virtual methods with 'virtual'
 
 At this point, all methods are marked with either 'virtual', 'final',
 'abstract', or 'override' or are implicitly final. (eg template methods,
 constructors)
 
 4. Do not require 'final' to mark a function as final. (optional)


 
 Since I already started writing this, I may as well paste it here:
 http://wiki.dlang.org/DIP51
 It can be updated if details emerge.


 
 I updated it.  The warning goes on the introducing method, not on the
 overriding one.  This forces all methods to be correctly annotated, even if
 there are no derived classes.


You mean to disallow an implicit state? So it's not final-by-default, rather,
it MUST be explicitly specified?

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prev sibling next sibling parent d-bugmail puremagic.com writes:
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 You mean to disallow an implicit state? So it's not final-by-default, rather,
 it MUST be explicitly specified?


final-by-default comes last.  The plan is to force the user to annotate
everything, then relax the rules again.  This way no functions move from
virtual->non-virtual without user intervention.

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 You mean to disallow an implicit state? So it's not final-by-default, rather,
 it MUST be explicitly specified?


 
 final-by-default comes last.  The plan is to force the user to annotate
 everything, then relax the rules again.  This way no functions move from
 virtual->non-virtual without user intervention.


Hmmm, okay. I guess that's fair enough. It makes it explicit for a while then
there's no ambiguity of intent.

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prev sibling next sibling parent d-bugmail puremagic.com writes:
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12:58:07 PST ---
*** Issue 7726 has been marked as a duplicate of this issue. ***

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Feb 12 2014
prev sibling next sibling parent d-bugmail puremagic.com writes:
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Commits pushed to master at https://github.com/D-Programming-Language/dmd

https://github.com/D-Programming-Language/dmd/commit/b900262a9cbde7247a5eb0abc9de218500f7e229
Issue 11616 - Introduce virtual keyword

Introduce the virtual keyword

https://github.com/D-Programming-Language/dmd/commit/28acc4a364f751225b544b12c082dab037783d12


Issue 11616 - Introduce virtual keyword

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prev sibling next sibling parent d-bugmail puremagic.com writes:
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bearophile_hugs eml.cc changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bearophile_hugs eml.cc



A possibly silly question, is this code OK (currently it compiles)?


class Foo {
    virtual final void bar() {}
}
void main() {}

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prev sibling next sibling parent d-bugmail puremagic.com writes:
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 A possibly silly question, is this code OK (currently it compiles)?
 
 
 class Foo {
     virtual final void bar() {}
 }
 void main() {}


An oversight, it should give you an error the same as ` safe  system void
fun();`  does.  Please file a bug for it.

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prev sibling next sibling parent d-bugmail puremagic.com writes:
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 An oversight, it should give you an error the same as ` safe  system void
 fun();`  does.  Please file a bug for it.


Yet it seems C++11 allows it:

http://en.wikipedia.org/wiki/C%2B%2B0x#Explicit_overrides_and_final

http://stackoverflow.com/questions/6788338/final-virtual-functions-in-c0x

http://stackoverflow.com/questions/11704406/whats-the-point-of-a-final-virtual-function

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prev sibling parent d-bugmail puremagic.com writes:
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 An oversight, it should give you an error the same as ` safe  system void
 fun();`  does.  Please file a bug for it.


 
 Yet it seems C++11 allows it:
 
 http://en.wikipedia.org/wiki/C%2B%2B0x#Explicit_overrides_and_final
 
 http://stackoverflow.com/questions/6788338/final-virtual-functions-in-c0x
 
 http://stackoverflow.com/questions/11704406/whats-the-point-of-a-final-virtual-function


Interesting...  Still, because we have attribute scopes/labels that would be
harmful in D.

eg

virtual:
final:
    void fun();

Here fun should be final, not both virtual and final.  This should behave the
same way as "virtual final".

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