I am asking for some advice on a problem that is hard to understand about the delegate of the Unreal Engine.

Development Programming & Scripting C++
, , ,
3

Thank you for reply. But I did not have a luck.

#include "SomeEmptyPlugin.h"
#include<functional> 

#define LOCTEXT_NAMESPACE "FSomeEmptyPluginModule"

void FSomeEmptyPluginModule::SomeTest()
{
	DelegateWithoutPayload.BindRaw(
	this
	, &FSomeEmptyPluginModule::FunctionWithoutParameter
	);

	DelegateWithValuePayload.BindRaw(
		this
		, &FSomeEmptyPluginModule::FunctionWithValueParameter
		, SomeStruct
		);

	DelegateWithPointerPayload.BindRaw(
		this
		, &FSomeEmptyPluginModule::FunctionWithPointerParameter
		, &SomeStruct
		);
	
	DelegateWithReferencePayload.BindRaw(
		this
		, &FSomeEmptyPluginModule::FunctionWithReferenceParameter
		, std::ref(SomeStruct)
		);
	
	void (FSomeEmptyPluginModule::*SomeFunctionPtrWithValueParam)(FSomeStruct) = nullptr;
	SomeFunctionPtrWithValueParam = &FSomeEmptyPluginModule::FunctionWithValueParameter;
	(this->*SomeFunctionPtrWithValueParam)(this->SomeStruct);

	void (FSomeEmptyPluginModule::*SomeFunctionPtrWithRefParam)(FSomeStruct&) = nullptr;
	SomeFunctionPtrWithRefParam = &FSomeEmptyPluginModule::FunctionWithReferenceParameter;
	(this->*SomeFunctionPtrWithRefParam)(this->SomeStruct);
	
}

And I got this message. In IDE Toolip,

No viable function. Argument types: FSomeEmptyPluginModule*, void(FSomeEmptyPluginModule::*)(FSomeStruct&), std::reference_wrapper<FSomeStruct>. Candidates considered:   inline void BindRaw<UserClass, VarTypes...>(UserClass* InUserObject, typename TMemFunPtrType<false, UserClass, TDelegate<void()>::RetValType(std::decay_t<VarTypes>...)>::Type InFunc, VarTypes&&...) (in class TDelegate<void(), FDefaultDelegateUserPolicy>)     conversion of 2nd argument &FSomeEmptyPluginModule::FunctionWithReferenceParameter is ill-formed: cannot convert void(FSomeEmptyPluginModule::*)(FSomeStruct&) to parameter type TMemFunPtrType<false, FSomeEmptyPluginModule, TDelegate<void()>::RetValType(std::decay_t<std::reference_wrapper<FSomeStruct>>)>::Type (aka void(FSomeEmptyPluginModule::*)(std::reference_wrapper<FSomeStruct>)),       because source function and target function have different 1st parameter types: FSomeStruct& and std::reference_wrapper<FSomeStruct>   inline void BindRaw<UserClass, VarTypes...>(const UserClass* InUserObject, typename TMemFunPtrType<true, UserClass, TDelegate<void()>::RetValType(std::decay_t<VarTypes>...)>::Type InFunc, VarTypes&&...) (in class TDelegate<void(), FDefaultDelegateUserPolicy>)     conversion of 2nd argument &FSomeEmptyPluginModule::FunctionWithReferenceParameter is ill-formed: cannot convert void(FSomeEmptyPluginModule::*)(FSomeStruct&) to parameter type TMemFunPtrType<true, FSomeEmptyPluginModule, TDelegate<void()>::RetValType(std::decay_t<std::reference_wrapper<FSomeStruct>>)>::Type (aka void(FSomeEmptyPluginModule::*)(std::reference_wrapper<FSomeStruct>) const),       because target function has const qualifier

And in the compile error,

0>Executing up to 12 actions based on MaxProcessorCount override
0>------ Building 4 action(s) started ------
0>[1/4] Compile [x64] Module.SomeEmptyPlugin.cpp
0>SomeEmptyPlugin.cpp(27): Error C2665 : 'TDelegate<void (void),FDefaultDelegateUserPolicy>::BindRaw': no overloaded function could convert all the argument types
0>DelegateSignatureImpl.inl(400): Reference  : could be 'void TDelegate<void (void),FDefaultDelegateUserPolicy>::BindRaw<FSomeEmptyPluginModule,std::reference_wrapper<FSomeStruct>>(const UserClass *,void (__cdecl FSomeEmptyPluginModule::* )(std::reference_wrapper<FSomeStruct>) const,std::reference_wrapper<FSomeStruct> &&)'
0>        with
0>        [
0>            UserClass=FSomeEmptyPluginModule
0>        ]
0>SomeEmptyPlugin.cpp(27): Reference  : 'void TDelegate<void (void),FDefaultDelegateUserPolicy>::BindRaw<FSomeEmptyPluginModule,std::reference_wrapper<FSomeStruct>>(const UserClass *,void (__cdecl FSomeEmptyPluginModule::* )(std::reference_wrapper<FSomeStruct>) const,std::reference_wrapper<FSomeStruct> &&)': cannot convert argument 2 from 'void (__cdecl FSomeEmptyPluginModule::* )(FSomeStruct &)' to 'void (__cdecl FSomeEmptyPluginModule::* )(std::reference_wrapper<FSomeStruct>) const'
0>        with
0>        [
0>            UserClass=FSomeEmptyPluginModule
0>        ]
0>SomeEmptyPlugin.cpp(29): Reference  : Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or parenthesized function-style cast
0>DelegateSignatureImpl.inl(393): Reference  : or       'void TDelegate<void (void),FDefaultDelegateUserPolicy>::BindRaw<FSomeEmptyPluginModule,std::reference_wrapper<FSomeStruct>>(UserClass *,void (__cdecl FSomeEmptyPluginModule::* )(std::reference_wrapper<FSomeStruct>),std::reference_wrapper<FSomeStruct> &&)'
0>        with
0>        [
0>            UserClass=FSomeEmptyPluginModule
0>        ]
0>SomeEmptyPlugin.cpp(27): Reference  : 'void TDelegate<void (void),FDefaultDelegateUserPolicy>::BindRaw<FSomeEmptyPluginModule,std::reference_wrapper<FSomeStruct>>(UserClass *,void (__cdecl FSomeEmptyPluginModule::* )(std::reference_wrapper<FSomeStruct>),std::reference_wrapper<FSomeStruct> &&)': cannot convert argument 2 from 'void (__cdecl FSomeEmptyPluginModule::* )(FSomeStruct &)' to 'void (__cdecl FSomeEmptyPluginModule::* )(std::reference_wrapper<FSomeStruct>)'
0>        with
0>        [
0>            UserClass=FSomeEmptyPluginModule
0>        ]
0>SomeEmptyPlugin.cpp(29): Reference  : Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or parenthesized function-style cast
0>SomeEmptyPlugin.cpp(27): Reference  : while trying to match the argument list '(FSomeEmptyPluginModule *, void (__cdecl FSomeEmptyPluginModule::* )(FSomeStruct &), std::reference_wrapper<FSomeStruct>)'