Boost:Bind//Boost:Function -- Need some help with a constructor trying to bind to a function
I am struggling to try to get bind/function working like I want. Some code
first though:
1. We have a POD object.
namespace POD{ class POD{};}
2. We have another class that wants to do something with a POD*.
namespace Alpha{ class MethodsInHere{
void doesSomething(POD::POD* arg0){}
};}
3. We have a third class, essentially a function handler, that has a
boost::function reference whose signature matches the method in #2, and a
constructor which wants to set the reference.
namespace EventHandler{ class EventHandler{
public:
EventHandler(boost::function
Charles Milutinovic
namespace Alpha{ class MethodsInHere{ void doesSomething(POD::POD* arg0){} };}
[snip]
namespace EventHandler{ class EventHandler{ public: EventHandler(boost::function
& function) : assign_to_me(function){} boost::function & assign_to_me; };}
<aside> I don't think you want assign_to_me to be a reference, but just hold by value. Otherwise you're holding a reference to a temporary below. </aside>
Alpha::MethodsInHere mih; EventHandler eh(boost::bind(&Alpha::MethodsInHere::doesSomething, ????, _1))
--------My question is basically if this is possible. I was having a ton of trouble getting this to work, and after digging through some docs it seems like the '?????' in line of code in #4 needs to be a reference to eh . . . which isn't constructed yet. If I'm wrong, please tell me how to construct this bind properly. [snip]
Sorry, but you're wrong. You want "????" to be "mih", not "eh". "doesSomething"'s type is basically "(Alpha::MethodsInHere&, POD::POD*) -> void" hence you need and instance of Alpha::MethodsInHere. HTH, -Ryan
You're absolutely right about the reference. That led to a process of
chasing bugs in much more complex code than in my example that made me
sprint right past the way to properly use the boost::bind/boost::function
pair I needed in my event handler because I attributed some seg faults to
it.
Do not code while half asleep!
Thank you for your and Alan's reply.
On Sun, Nov 2, 2008 at 6:57 PM, Ryan Gallagher
Charles Milutinovic
writes: [snip] namespace Alpha{ class MethodsInHere{ void doesSomething(POD::POD* arg0){} };}
[snip]
namespace EventHandler{ class EventHandler{ public: EventHandler(boost::function
& function) : assign_to_me(function){} boost::function & assign_to_me; };} <aside> I don't think you want assign_to_me to be a reference, but just hold by value. Otherwise you're holding a reference to a temporary below. </aside>
Alpha::MethodsInHere mih; EventHandler eh(boost::bind(&Alpha::MethodsInHere::doesSomething, ????, _1))
--------My question is basically if this is possible. I was having a ton of trouble getting this to work, and after digging through some docs it seems like the '?????' in line of code in #4 needs to be a reference to eh . . . which isn't constructed yet. If I'm wrong, please tell me how to construct this bind properly. [snip]
Sorry, but you're wrong. You want "????" to be "mih", not "eh". "doesSomething"'s type is basically "(Alpha::MethodsInHere&, POD::POD*) -> void" hence you need and instance of Alpha::MethodsInHere. HTH,
-Ryan
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participants (2)
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Charles Milutinovic -
Ryan Gallagher