2013-08-09 12:17, Murray Cumming skrev:
On Thu, 2013-08-08 at 16:40 +0200, Kjell Ahlstedt wrote:
Templated get_*() methods can be added as overloaded methods, because
the number of parameters will be different. Example:
_WRAP_METHOD(Glib::VariantBase get_action_state(const
Glib::ustring& action_name) const,
g_action_group_get_action_state)
template <typename T_Value>
void get_action_state(const Glib::ustring& action_name,
T_Value& value) const;
It's also possible to deprecate the old get_action_state() and add a
new get_action_state_variant(), identical except for its name.
Yes, thanks for the suggestion. I've done that.
I'm not sure whether it's possible to overload other methods, e.g.
_WRAP_METHOD(void change_action_state(const Glib::ustring&
action_name, const Glib::VariantBase& value),
g_action_group_change_action_state)
template <typename T_Value>
void change_action_state(const Glib::ustring& action_name,
const T_Value& value);
Overload resolution prefers a non-template method to a template
method, but perhaps that's true only when the parameter types exactly
match those of the non-template method. The last parameter in a
typical call would not be a Glib::VariantBase& but a
Glib::Variant<T>&.
I tried. But you are right, the compiler calls the templated
change_state<>() with the Variant<>, trying to call
change_state_variant() with a Variant<Variant<int>>, for instance. At
least that would be an API change instead of an ABI change,
because existing already-compiled applications would be unaffected, but
it would be a hard one to detect.
So, in Action, I added
template<typename T_Value>
void change_state(const Glib::Variant<T_Value>& value)
to give the compiler something to call.
https://git.gnome.org/browse/glibmm/commit/?id=8acf6182ee6e54040cec1a049704c7563f67475a
Hopefully there's no case where someone would really want to call
change_state() with a Variant.
It seems to work. Does it seem OK to you? If so, I'll do it for similar
API.
Yes, it seems to work. I tested with the attached short program. No
complaints about ambiguous calls, and the correct template
change_state() function is called in both calls. I see no problem with
this solution.
#include <giomm.h>
#include <glibmm.h>
int main()
{
Gio::init();
Glib::RefPtr<Gio::SimpleAction> action1 =
Gio::SimpleAction::create("action1", Glib::VariantType("i"), Glib::Variant<gint32>::create(0));
Glib::Variant<gint32> variant32 = Glib::Variant<gint32>::create(17);
action1->change_state(variant32);
action1->change_state(17);
return 0;
}
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