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Using g_signal_connect in class
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Using g_signal_connect in class
by Marco Rocco
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Hello, this is my first post on this mailing list, now i do my request:
can i use g_signal_connect in a method of my class, using as c_handler a private function of class? ...and if i can, how i can do ? _______________________________________________ gtk-list mailing list gtk-list@... http://mail.gnome.org/mailman/listinfo/gtk-list |
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Re: Using g_signal_connect in class
by Murray Cumming
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On Tue, 2008-07-15 at 12:04 +0200, Marco Rocco wrote:
> Hello, this is my first post on this mailing list, now i do my request: > can i use g_signal_connect in a method of my class, using as c_handler > a private function of class? ...and if i can, how i can do ? You are talking about C++, I believe. The answer is No, not unless your method is a static method. gtkmm makes this possible, using libsigc++ slots. -- murrayc@... www.murrayc.com www.openismus.com _______________________________________________ gtk-list mailing list gtk-list@... http://mail.gnome.org/mailman/listinfo/gtk-list |
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RE: Using g_signal_connect in class
by Vallone, Anthony
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Only if the member function is static. Calling a non-static member
function requires two addresses: the instance address and the function address. Whether its public or private doesn't matter because access to function pointers is not checked by compilers. I frequently do something like this: class SomeClass { ... private: ... static void staticCb(..., gpointer inInstance) { SomeClass* instance = (SomeClass*)inInstance; instance->callback(...); } void callback(...) { ... } ... void someFunc() { ... g_signal_connect(..., G_CALLBACK(&staticCb), this); ... } ... }; -Anthony Vallone -----Original Message----- From: gtk-list-bounces@... [mailto:gtk-list-bounces@...] On Behalf Of Marco Rocco Sent: Tuesday, July 15, 2008 6:04 AM To: gtk-list@... Subject: Using g_signal_connect in class Hello, this is my first post on this mailing list, now i do my request: can i use g_signal_connect in a method of my class, using as c_handler a private function of class? ...and if i can, how i can do ? _______________________________________________ gtk-list mailing list gtk-list@... http://mail.gnome.org/mailman/listinfo/gtk-list _______________________________________________ gtk-list mailing list gtk-list@... http://mail.gnome.org/mailman/listinfo/gtk-list |
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Re: Using g_signal_connect in class
by Chris Vine
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On Tue, 15 Jul 2008 11:34:41 -0400
"Vallone, Anthony" <anthony.vallone@...> wrote: > Only if the member function is static. Calling a non-static member > function requires two addresses: the instance address and the function > address. Whether its public or private doesn't matter because access > to function pointers is not checked by compilers. I frequently do > something like this: > > class SomeClass > { > ... > private: > ... > static void staticCb(..., gpointer inInstance) { > SomeClass* instance = (SomeClass*)inInstance; > instance->callback(...); > } > void callback(...) { > ... > } > ... > void someFunc() { > ... > g_signal_connect(..., G_CALLBACK(&staticCb), this); > ... > } > ... > }; This will work with gcc/g++ but it is not standard conforming, as static class functions do not have C linkage, and the C++ standard states that functions otherwise identical with C++ and C linkage are different types. To be standard conforming you should use a friend function (if it needs access to private data) declared extern "C". Chris _______________________________________________ gtk-list mailing list gtk-list@... http://mail.gnome.org/mailman/listinfo/gtk-list |
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Re: Using g_signal_connect in class
by Jean Bréfort
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Le samedi 19 juillet 2008 à 12:29 +0100, Chris Vine a écrit :
> On Tue, 15 Jul 2008 11:34:41 -0400 > "Vallone, Anthony" <anthony.vallone@...> wrote: > > > Only if the member function is static. Calling a non-static member > > function requires two addresses: the instance address and the function > > address. Whether its public or private doesn't matter because access > > to function pointers is not checked by compilers. I frequently do > > something like this: > > > > class SomeClass > > { > > ... > > private: > > ... > > static void staticCb(..., gpointer inInstance) { > > SomeClass* instance = (SomeClass*)inInstance; > > instance->callback(...); > > } > > void callback(...) { > > ... > > } > > ... > > void someFunc() { > > ... > > g_signal_connect(..., G_CALLBACK(&staticCb), this); > > ... > > } > > ... > > }; > > This will work with gcc/g++ but it is not standard conforming, as > static class functions do not have C linkage, and the C++ standard > states that functions otherwise identical with C++ and C linkage are > different types. > > To be standard conforming you should use a friend function (if it needs > access to private data) declared extern "C". > > Chris The extern "C" declaration is not needed. Regards, Jean _______________________________________________ gtk-list mailing list gtk-list@... http://mail.gnome.org/mailman/listinfo/gtk-list |
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Re: Using g_signal_connect in class
by Chris Vine
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On Sat, 19 Jul 2008 13:42:58 +0200
Jean Bréfort <jean.brefort@...> wrote: > Le samedi 19 juillet 2008 à 12:29 +0100, Chris Vine a écrit : > > This will work with gcc/g++ but it is not standard conforming, as > > static class functions do not have C linkage, and the C++ standard > > states that functions otherwise identical with C++ and C linkage are > > different types. > > > > To be standard conforming you should use a friend function (if it > > needs access to private data) declared extern "C". > > The extern "C" declaration is not needed. Are you saying there is a misprint in the C++ standard, or that with the particular compiler you use it is not necessary? If the latter, what part of my post do you disagree with? Chris _______________________________________________ gtk-list mailing list gtk-list@... http://mail.gnome.org/mailman/listinfo/gtk-list |
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Re: Using g_signal_connect in class
by milosz derezynski
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I think he meant that in order to use the function with g_signal_connect(), a C linkage is not needed (and i think this is actually right, too).
2008/7/19 Chris Vine <chris@...>:
-- ------------ Please note that according to the German law on data retention, information on every electronic information exchange with me is retained for a period of six months. [Bitte beachten Sie, dass dem Gesetz zur Vorratsdatenspeicherung zufolge jeder elektronische Kontakt mit mir sechs Monate lang gespeichert wird.] _______________________________________________ gtk-list mailing list gtk-list@... http://mail.gnome.org/mailman/listinfo/gtk-list |
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Re: Using g_signal_connect in class
by Chris Vine
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On Sat, 19 Jul 2008 16:40:17 +0200
"Milosz Derezynski" <internalerror@...> wrote: > I think he meant that in order to use the function with > g_signal_connect(), a C linkage is not needed (and i think this is > actually right, too). No, g_signal_connect() takes a function pointer and in C++ function pointers have a linkage type. For GObject/GTK functions they have C linkage type. By default, when compiled in a C++ environment non-member functions and non-member function pointers have C++ linkage type, so that amongst other things functions can be overloaded, but some compilers may also keep arguments on the stack for function calls with C linkage differently from functions calls with C++ linkage. The way to give them C linkage type is to declare them extern "C". Passing functions with C++ linkage type as GSignal callbacks works with gcc/g++, but it is not guaranteed by the standard. For more discussion you might want to read section 9.2.5 of TC++PL. Chris _______________________________________________ gtk-list mailing list gtk-list@... http://mail.gnome.org/mailman/listinfo/gtk-list |
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RE: Using g_signal_connect in class
by Vallone, Anthony
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Thanks for the linkage info Chris. I've been using static class members
successfully with the Sun compiler on Solaris, but I'll start declaring my callbacks with c linkage to be standard conforming. Sun's documentation gives the same advice: https://developers.sun.com/solaris/articles/mixing.html -Anthony Vallone -----Original Message----- From: gtk-list-bounces@... [mailto:gtk-list-bounces@...] On Behalf Of Chris Vine Sent: Saturday, July 19, 2008 4:51 PM To: Milosz Derezynski Cc: gtk-list@...; Vallone, Anthony Subject: Re: Using g_signal_connect in class On Sat, 19 Jul 2008 16:40:17 +0200 "Milosz Derezynski" <internalerror@...> wrote: > I think he meant that in order to use the function with > g_signal_connect(), a C linkage is not needed (and i think this is > actually right, too). No, g_signal_connect() takes a function pointer and in C++ function pointers have a linkage type. For GObject/GTK functions they have C linkage type. By default, when compiled in a C++ environment non-member functions and non-member function pointers have C++ linkage type, so that amongst other things functions can be overloaded, but some compilers may also keep arguments on the stack for function calls with C linkage differently from functions calls with C++ linkage. The way to give them C linkage type is to declare them extern "C". Passing functions with C++ linkage type as GSignal callbacks works with gcc/g++, but it is not guaranteed by the standard. For more discussion you might want to read section 9.2.5 of TC++PL. Chris _______________________________________________ gtk-list mailing list gtk-list@... http://mail.gnome.org/mailman/listinfo/gtk-list _______________________________________________ gtk-list mailing list gtk-list@... http://mail.gnome.org/mailman/listinfo/gtk-list |
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