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digitalmars.D.bugs - [Issue 8031] New: If a class have some signals it's impossible for a derived class to have any signals

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=8031

           Summary: If a class have some signals it's impossible for a
                    derived class to have any signals
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: blocker
          Priority: P2
         Component: Phobos
        AssignedTo: nobody puremagic.com
        ReportedBy: verylonglogin.reg gmail.com


--- Comment #0 from Denis <verylonglogin.reg gmail.com> 2012-05-04 14:55:44 MSD
---
`Signal` methods should never ever by virtual. We don't want user to override
connect/disconnect etc.

All `Signal` methods are virtual. As a result with current named mixin
templates behavior (they can add virtual methods):
---
import std.signals;

class A {
    mixin Signal created;
}
class B : A {
    mixin Signal moved; // Yes, it overrides `created` signal!
}
---
or even worse:
---
import std.signals;

class A {
    mixin Signal s1;
    mixin Signal s2;
}

class B : A {
    mixin Signal s3; // Guess what A signal is overriden?
}
---
or even worse:
---
import std.signals;

class A {
    mixin Signal s1;
}

class B : A {
    // Guess what exectly is overriden?
    // Spoiler: unhook is overriden!
    mixin Signal!int s2;
}
---

Hello heisenbugs for every unlucky person who doesn't compile with `-w`!

That's why it's impossible to use `std.signals` in any GUI library for now.

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next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=8031



--- Comment #1 from github-bugzilla puremagic.com 2012-07-01 19:25:08 PDT ---
Commit pushed to master at https://github.com/D-Programming-Language/phobos

https://github.com/D-Programming-Language/phobos/commit/05a8f316e7e497bcf3c44a5607a9a87da207a7d6
Fix Issue 8031 - If a class have some signals it's impossible for a derived
class to have any signals

All `Signal` methods should be `final` because if they aren't it's impossible
to add any signals into a derived class.

And yes, lets make `Signal` a `mixin template`.

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prev sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=8031


Denis Shelomovskij <verylonglogin.reg gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED


--- Comment #2 from Denis Shelomovskij <verylonglogin.reg gmail.com> 2012-07-06
10:42:02 MSD ---
Since https://github.com/D-Programming-Language/phobos/pull/567 has been merged
now it's impossible for a derived class to have signals only if a base class
has the one and only signal (because of Issue 5028) and this isn't a major luck
of functionality.

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