C++ lambda callbacks, how to initialize with NULL pointer ?
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Hi all, I need callback functions between different classes. I had already a solution based on stl, which was compilable with VS2010. Unfortunately I was not able to find a way to compile it with VS2015. I got weird error messages. Now I found a solution with lamda C++11 lambda function pointers. Actually it works, but I have one open issue. For having a save source code, I want to initialize the function pointer with NULL. But compiler is producing weird error messages again! My Code:
typedef std::function _tcedit_cb_;
class MyClass
{
public:
MyClass ()
{
m_cbGetItemData = NULL; // <--- compile error because of the NULL pointer
}
_tcedit_cb_ m_cbGetItemData;...
}How I can initialize the function callback pointer? I need to initialize in order to avoid running into illegal code! e.g. I tried to cast ... = (_tcedit_cb_) NULL; error messages:
c:\program files(x86)\microsoft visual studio 14.0\vc\include\type_traits(1501) : error C2893 : Failed to specialize function template 'unknown-type std::invoke(_Callable &&,_Types &&...)'
1> c:\program files(x86)\microsoft visual studio 14.0\vc\include\type_traits(1501) : note : With the following template arguments :
1> c:\program files(x86)\microsoft visual studio 14.0\vc\include\type_traits(1501) : note : '_Callable=_Decayed &'
1> c:\program files(x86)\microsoft visual studio 14.0\vc\include\type_traits(1501) : note : '_Types={int, int, ATL::CStringT>> }'
1> c:\program files(x86)\microsoft visual studio 14.0\vc\include\functional(210) : note : see reference to function template instantiation '_Rx std::_Invoke_ret<_Rx,_Callable&,_Ty,_Ty,ATL::CStringT>>>(std::_Forced<_Rx,false>,_Callable &,_Ty &&,_Ty &&,ATL::CStringT>> &&)' being compiled
1> with
1>[
1> _Rx = bool,
1> _Callable = _Decayed,
1> _Ty = int
1>] -
Hi all, I need callback functions between different classes. I had already a solution based on stl, which was compilable with VS2010. Unfortunately I was not able to find a way to compile it with VS2015. I got weird error messages. Now I found a solution with lamda C++11 lambda function pointers. Actually it works, but I have one open issue. For having a save source code, I want to initialize the function pointer with NULL. But compiler is producing weird error messages again! My Code:
typedef std::function _tcedit_cb_;
class MyClass
{
public:
MyClass ()
{
m_cbGetItemData = NULL; // <--- compile error because of the NULL pointer
}
_tcedit_cb_ m_cbGetItemData;...
}How I can initialize the function callback pointer? I need to initialize in order to avoid running into illegal code! e.g. I tried to cast ... = (_tcedit_cb_) NULL; error messages:
c:\program files(x86)\microsoft visual studio 14.0\vc\include\type_traits(1501) : error C2893 : Failed to specialize function template 'unknown-type std::invoke(_Callable &&,_Types &&...)'
1> c:\program files(x86)\microsoft visual studio 14.0\vc\include\type_traits(1501) : note : With the following template arguments :
1> c:\program files(x86)\microsoft visual studio 14.0\vc\include\type_traits(1501) : note : '_Callable=_Decayed &'
1> c:\program files(x86)\microsoft visual studio 14.0\vc\include\type_traits(1501) : note : '_Types={int, int, ATL::CStringT>> }'
1> c:\program files(x86)\microsoft visual studio 14.0\vc\include\functional(210) : note : see reference to function template instantiation '_Rx std::_Invoke_ret<_Rx,_Callable&,_Ty,_Ty,ATL::CStringT>>>(std::_Forced<_Rx,false>,_Callable &,_Ty &&,_Ty &&,ATL::CStringT>> &&)' being compiled
1> with
1>[
1> _Rx = bool,
1> _Callable = _Decayed,
1> _Ty = int
1>]Here's a stab in the dark: Instead of initializing to
NULL, try setting it tonullptr.The difficult we do right away... ...the impossible takes slightly longer.
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Here's a stab in the dark: Instead of initializing to
NULL, try setting it tonullptr.The difficult we do right away... ...the impossible takes slightly longer.
oh....you are right! with
nullptrit works!!! never, never used it before! Many Thanks Richard
