Opened 6 years ago
#12483 new Support Requests
signals2 bind to member function by value fail to signal when using trackable
| Reported by: | Owned by: | Douglas Gregor | |
|---|---|---|---|
| Milestone: | To Be Determined | Component: | signals |
| Version: | Boost 1.61.0 | Severity: | Not Applicable |
| Keywords: | signals2 trackable bind | Cc: |
Description
In my trail to learn and get comfortable with signals2 I wrote a small test program. In this program I encountered what I believe to be inconsistency in the way that signals2 connect to member functions when using bind, when using trackable aswell.
Test program:
#include "boost/signals2.hpp" #include <iostream> class SignalTest : public boost::signals2::trackable { public: SignalTest() {}; void printInfo(const std::string name, int num) { std::cout << "Signal: " << name << " " << num << std::endl; } }; int main() { boost::signals2::signal<void (const std::string&, int)> sig; SignalTest test1; sig.connect(boost::bind(&SignalTest::printInfo, test1, _1, _2)); sig("Test", 1); { SignalTest test2; sig.connect(boost::bind(&SignalTest::printInfo, test2, _1, _2)); sig("Test", 2); } return 0; }
The code above compiles and running it I'd expect both signals to be printed, however nothing is printed. If however I bind the signalTest object "test2" by reference like the code below:
Bind by reference:
sig.connect(boost::bind(&SignalTest::printInfo, &test2, _1, _2));
The following is printed:
test2 bind by reference print
Signal: Test 2
And if I also bind signalTest object "test1" by reference the following is printed:
test1 and test2 bind by reference print
Signal: Test 1 Signal: Test 2 Signal: Test 2
As I was lead to understand from the example code of section "Automatic Connection Management" in the tutorial at http://www.boost.org/doc/libs/1_61_0/doc/html/signals2/tutorial.html#idp394616720 I should be able to call the member function by value, however this is not the case using trackable.
