[Issue 2557] inconsistent behavior when taking reference to member without instance
https://issues.dlang.org/show_bug.cgi?id=2557 Mike Franklin changed: What|Removed |Added Status|NEW |RESOLVED Resolution|--- |WONTFIX --
[Issue 2557] inconsistent behavior when taking reference to member without instance
https://issues.dlang.org/show_bug.cgi?id=2557 --- Comment #11 from Mike Franklin --- I tested the test case with DMD 2.077.1 and it correctly rejects taking a reference to a non-static member function through the type Also, the "Version" for this PR is listed as "D1 (Retired)". It is my understanding that D1 is no longer supported, so closing this issue. --
[Issue 2557] inconsistent behavior when taking reference to member without instance
https://issues.dlang.org/show_bug.cgi?id=2557
Mike Franklin changed:
What|Removed |Added
CC||slavo5...@yahoo.com
--- Comment #10 from Mike Franklin ---
For convenience, I'm adding the source code from the original post's attachment
here:
module method_ref;
class A {
void fun() {}
}
void main() {
/* This works correctly and can sometimes be very useful */
A a = new A;
void function() fn1 = &A.fun;
void delegate() dg1;
dg1.ptr = cast(void*)a;
dg1.funcptr = fn1;
dg1();
}
class B {
/+ static /* works if static */ +/ void dofun() {
/* Error: this for fun needs to be type A not type method_ref.B */
A a = new A;
void function() fn2 = &A.fun;
void delegate() dg2;
dg2.ptr = cast(void*)a;
dg2.funcptr = fn2;
dg2();
}
}
It can be tested online here: https://run.dlang.io/is/9GAvd4
--
[Issue 2557] inconsistent behavior when taking reference to member without instance
https://issues.dlang.org/show_bug.cgi?id=2557 Mike Franklin changed: What|Removed |Added See Also||https://issues.dlang.org/sh ||ow_bug.cgi?id=3720 --
[Issue 2557] inconsistent behavior when taking reference to member without instance
http://d.puremagic.com/issues/show_bug.cgi?id=2557 --- Comment #9 from d...@brian.codekitchen.net 2009-01-14 16:46 --- > It doesn't work. "works" means "behaves correctly", not "compiles without > error". I understand the difference between "works" and "compiles', it does work in my testing. The method body I'm taking a pointer to is empty in the test case but I first ran into this inconsistency while refactoring some code, where the method body was *not* empty and the code inside the method executed correctly. Whether it *should* work or not is certainly debatable, but I find it a useful behavior except for the inconsistency shown. --
[Issue 2557] inconsistent behavior when taking reference to member without instance
http://d.puremagic.com/issues/show_bug.cgi?id=2557 --- Comment #8 from s...@iname.com 2009-01-12 07:15 --- (In reply to comment #7) > Makes sense. Perhaps, another enhancement report should be created with a > request to change typeof(&A.foo) from void function() to void delegate() with > a > dg.ptr being null. That would still be prone to accidental misuse IMO. Really, D should do one of the following: (a) add method pointer types (b) define &A.foo to be of a type that has the context pointer as just another parameter (which might break if ABI changes to support function-to-delegate conversion are implemented) (c) (continue to) disallow &A.foo altogether --
[Issue 2557] inconsistent behavior when taking reference to member without instance
http://d.puremagic.com/issues/show_bug.cgi?id=2557 --- Comment #7 from 2kor...@gmail.com 2009-01-12 04:53 --- Makes sense. Perhaps, another enhancement report should be created with a request to change typeof(&A.foo) from void function() to void delegate() with a dg.ptr being null. --
[Issue 2557] inconsistent behavior when taking reference to member without instance
http://d.puremagic.com/issues/show_bug.cgi?id=2557 --- Comment #6 from s...@iname.com 2009-01-12 03:09 --- (In reply to comment #5) > That's a feature! Even if method is not static, it still has a single unique > body. If so, why can't you take its address? http://www.digitalmars.com/d/1.0/type.html#delegates "There are no pointers-to-members in D, but a more useful concept called delegates are supported." Even if there were, the type would not be void function() as is declared in the attached code, but rather void function(A) or perhaps something like void A.function() akin to C++ notation (IIRC) void (A::*)() Maybe void function() would work if the calling convention specifies that the context pointer be always passed in a register that is never used for any other kind of function argument, but that isn't the case in the current ABI. --
[Issue 2557] inconsistent behavior when taking reference to member without instance
http://d.puremagic.com/issues/show_bug.cgi?id=2557 --- Comment #5 from 2kor...@gmail.com 2009-01-12 00:26 --- That's a feature! Even if method is not static, it still has a single unique body. If so, why can't you take its address? --
[Issue 2557] inconsistent behavior when taking reference to member without instance
http://d.puremagic.com/issues/show_bug.cgi?id=2557 --- Comment #4 from s...@iname.com 2009-01-11 19:09 --- But your code tries to use &A.fun, not &a.fun. For &A.fun to make any sense with A being a type, fun would have to be a static method of A. --
[Issue 2557] inconsistent behavior when taking reference to member without instance
http://d.puremagic.com/issues/show_bug.cgi?id=2557 --- Comment #3 from 2kor...@gmail.com 2009-01-11 17:42 --- (In reply to comment #2) > The code is wrong regardless of whether dofun is static or not. A.fun needs > an > object of type A. But it doesn't have one. > I'm not so sure. Object of type A is provided by these two lines of code: A a = new A; dg2.ptr = cast(void*)a; --
[Issue 2557] inconsistent behavior when taking reference to member without instance
http://d.puremagic.com/issues/show_bug.cgi?id=2557 s...@iname.com changed: What|Removed |Added CC||s...@iname.com Keywords||accepts-invalid --- Comment #2 from s...@iname.com 2009-01-11 17:28 --- It doesn't work. "works" means "behaves correctly", not "compiles without error". The code is wrong regardless of whether dofun is static or not. A.fun needs an object of type A. But it doesn't have one. -- bz2557.d(21): Error: this for fun needs to be type A not type method_ref.B bz2557.d(21): Error: cannot implicitly convert expression (&this.fun) of type void delegate() to void function() -- --
[Issue 2557] inconsistent behavior when taking reference to member without instance
http://d.puremagic.com/issues/show_bug.cgi?id=2557 --- Comment #1 from d...@brian.codekitchen.net 2009-01-05 09:50 --- Created an attachment (id=285) --> (http://d.puremagic.com/issues/attachment.cgi?id=285&action=view) test case --
