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Kjell Ahlstedt
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slot: Handle auto-disconnection when a slot contains a slot
* sigc++/functors/macros/slot.h.m4: Add sigc::visitor<> specializations for slot# and slot. * tests/test_disconnect.cc: Test auto-disconnection of a slot that contains a slot. Bug #755003.
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‎sigc++/functors/macros/slot.h.m4

Lines changed: 89 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -39,11 +39,6 @@ FOR(1,$1,[
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*
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* @ingroup slot
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*/
42-
/* TODO: Where put the following bit of information? I can't make any
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* sense of the "because", by the way!
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*
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* Because slot is opaque, visit_each() will not visit its internal members.
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*/
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template <LIST(class T_return, LOOP(class T_arg%1, $1))>
4843
class slot$1
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: public slot_base
@@ -122,9 +117,48 @@ FOR(1, $1,[
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}
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};
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#ifndef DOXYGEN_SHOULD_SKIP_THIS
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//template specialization of visitor<>::do_visit_each<>(action, functor):
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/** Performs a functor on each of the targets of a functor.
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* The function overloads for sigc::slot$1 are similar to the function
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* overloads for sigc::slot. See the description of those overloads.
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*
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* @ingroup slot
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*/
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template <LIST(typename T_return, LOOP(typename T_arg%1, $1))>
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struct visitor<slot$1<LIST(T_return, LOOP(T_arg%1, $1))>>
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{
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static void do_visit_each(const internal::limit_derived_target<trackable*, internal::slot_do_bind>& _A_action,
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const slot$1<LIST(T_return, LOOP(T_arg%1, $1))>& _A_target)
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{
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if (_A_target.rep_ && _A_target.rep_->parent_ == nullptr)
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_A_target.rep_->set_parent(_A_action.action_.rep_, &internal::slot_rep::notify);
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}
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static void do_visit_each(const internal::limit_derived_target<trackable*, internal::slot_do_unbind>& _A_action,
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const slot$1<LIST(T_return, LOOP(T_arg%1, $1))>& _A_target)
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{
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if (_A_target.rep_ && _A_target.rep_->parent_ == _A_action.action_.rep_)
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_A_target.rep_->set_parent(nullptr, nullptr);
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}
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template <typename T_action>
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static void do_visit_each(const T_action& _A_action,
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const slot$1<LIST(T_return, LOOP(T_arg%1, $1))>& _A_target)
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{
149+
_A_action(_A_target);
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}
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};
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#endif // DOXYGEN_SHOULD_SKIP_THIS
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125154
])
126155
define([SLOT],[dnl
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ifelse($1, $2,[dnl
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// Because slot is opaque, visit_each() will not visit its internal members.
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// Those members are not reachable by visit_each() after the slot has been
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// constructed. But when a slot contains another slot, the outer slot will become
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// the parent of the inner slot, with similar results. See the description of
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// slot's specialization of the visitor struct.
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/** Convenience wrapper for the numbered sigc::slot# templates.
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* Slots convert arbitrary functors to unified types which are opaque.
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* sigc::slot itself is a functor or to be more precise a closure. It contains
@@ -190,6 +224,56 @@ public:
190224
: parent_type(reinterpret_cast<const parent_type&>(src)) {}
191225
};
192226
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ifelse($1, $2,[dnl
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#ifndef DOXYGEN_SHOULD_SKIP_THIS
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//template specialization of visitor<>::do_visit_each<>(action, functor):
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/** Performs a functor on each of the targets of a functor.
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*
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* There are three function overloads for sigc::slot.
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*
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* The first two overloads are very specialized. They handle the (probably unusual)
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* case when the functor, stored in a slot, contains a slot. They are invoked from
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* the constructor, destructor or destroy() method of typed_slot_rep.
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* The first overload, called from the constructor of the outer slot, sets
238+
* the outer slot as the parent of the inner slot. The second overload, called from
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* the destructor or destroy() of the outer slot, unsets the parent of the inner slot.
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* When an object referenced from the inner slot is deleted, the inner slot calls
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* its slot_rep::disconnect(), which calls the outer slot's slot_rep::notify().
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* The outer slot is informed just as if one of its directly referenced objects
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* had been deleted. Result: The outer slot is disconnected from its parent,
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* if any (for instance a sigc::signal).
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* See https://bugzilla.gnome.org/show_bug.cgi?id=755003
246+
*
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* The third overload is identical to do_visit_each() in visitor's primary template.
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*
249+
* @ingroup slot
250+
*/
251+
template <LIST(typename T_return, LOOP(typename T_arg%1, $1))>
252+
struct visitor<slot<LIST(T_return, LOOP(T_arg%1, $1))>>
253+
{
254+
static void do_visit_each(const internal::limit_derived_target<trackable*, internal::slot_do_bind>& _A_action,
255+
const slot<LIST(T_return, LOOP(T_arg%1, $1))>& _A_target)
256+
{
257+
if (_A_target.rep_ && _A_target.rep_->parent_ == nullptr)
258+
_A_target.rep_->set_parent(_A_action.action_.rep_, &internal::slot_rep::notify);
259+
}
260+
261+
static void do_visit_each(const internal::limit_derived_target<trackable*, internal::slot_do_unbind>& _A_action,
262+
const slot<LIST(T_return, LOOP(T_arg%1, $1))>& _A_target)
263+
{
264+
if (_A_target.rep_ && _A_target.rep_->parent_ == _A_action.action_.rep_)
265+
_A_target.rep_->set_parent(nullptr, nullptr);
266+
}
267+
268+
template <typename T_action>
269+
static void do_visit_each(const T_action& _A_action,
270+
const slot<LIST(T_return, LOOP(T_arg%1, $1))>& _A_target)
271+
{
272+
_A_action(_A_target);
273+
}
274+
};
275+
#endif // DOXYGEN_SHOULD_SKIP_THIS
276+
])
193277
])
194278
define([SLOT_CALL],[dnl
195279
/** Abstracts functor execution.

‎tests/test_disconnect.cc

Lines changed: 37 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,3 @@
1-
// -*- c++ -*-
21
/* Copyright 2002, The libsigc++ Development Team
32
* Assigned to public domain. Use as you wish without restriction.
43
*/
@@ -7,6 +6,7 @@
76
#include <sigc++/trackable.h>
87
#include <sigc++/signal.h>
98
#include <sigc++/connection.h>
9+
#include <sigc++/adaptors/compose.h>
1010
#include <sigc++/functors/ptr_fun.h>
1111
#include <sigc++/functors/mem_fun.h>
1212
#include <sstream>
@@ -58,7 +58,7 @@ struct B : public sigc::trackable
5858

5959
void destroy() // Calling destroy() during signal emission seems weird!
6060
{ // However, if this works, anything will work!
61-
delete this;
61+
delete this; // valgrind reports a small memory leak, that's all.
6262
}
6363

6464
void boom()
@@ -127,6 +127,41 @@ int main(int argc, char* argv[])
127127

128128
cona.disconnect(); // already disconnected -> legal with connection objects, however, nothing happens ...
129129

130+
{
131+
A a2;
132+
sig.connect(sigc::compose(sigc::mem_fun(&a2, &A::foo), &foo));
133+
result_stream << "sig is connected to compose(A::foo, foo) (size=" << sig.size() << "): ";
134+
sig(7);
135+
util->check_result(result_stream, "sig is connected to compose(A::foo, foo) (size=1): foo(7) A::foo(1) ");
136+
}
137+
result_stream << "sig is empty (size=" << sig.size() << "): ";
138+
sig(8);
139+
util->check_result(result_stream, "sig is empty (size=0): ");
140+
141+
{ // A slot# within a slot
142+
A a2;
143+
sigc::slot1<int, int> setter = sigc::mem_fun(&a2, &A::foo);
144+
sig.connect(sigc::compose(setter, &foo));
145+
result_stream << "sig is connected to compose(slot1(A::foo), foo) (size=" << sig.size() << "): ";
146+
sig(9);
147+
util->check_result(result_stream, "sig is connected to compose(slot1(A::foo), foo) (size=1): foo(9) A::foo(1) ");
148+
}
149+
result_stream << "sig is empty (size=" << sig.size() << "): ";
150+
sig(10);
151+
util->check_result(result_stream, "sig is empty (size=0): ");
152+
153+
{ // A slot within a slot
154+
A a2;
155+
sigc::slot<int, int> setter = sigc::mem_fun(&a2, &A::foo);
156+
sig.connect(sigc::compose(setter, &foo));
157+
result_stream << "sig is connected to compose(slot(A::foo), foo) (size=" << sig.size() << "): ";
158+
sig(11);
159+
util->check_result(result_stream, "sig is connected to compose(slot(A::foo), foo) (size=1): foo(11) A::foo(1) ");
160+
}
161+
result_stream << "sig is empty (size=" << sig.size() << "): ";
162+
sig(12);
163+
util->check_result(result_stream, "sig is empty (size=0): ");
164+
130165
result_stream << "deleting a signal during emission... ";
131166
auto b = new B;
132167
b->emit();

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