[英]C++ member-function pointer
Consider the following class 考虑以下课程
class Foo
{
typedef bool (*filter_function)(Tree* node, std::list<std::string>& arg);
void filter(int filter, std::list<std::string>& args)
{
...
if (filter & FILTER_BY_EVENTS) {
do_filter(events_filter, args, false, filter & FILTER_NEGATION);
}
...
}
void do_filter(filter_function ff, std::list<std::string>& arg,
bool mark = false, bool negation = false, Tree* root = NULL)
{
...
}
bool events_filter(Tree* node, std::list<std::string>& arg)
{
...
}
};
I can pass events_filter
as a parameter to the do_filter
only when events_filter
is static
member. 只有当
events_filter
是static
成员时,我才能将events_filter
作为参数传递给do_filter
。 But I don't want to make it static
. 但我不想让它变得
static
。 Is there a way in which I can pass pointer to the member-function to another function? 有没有办法可以将指向成员函数的指针传递给另一个函数? May be using boost libraries (like function) or so.
可能正在使用boost库(如函数)左右。
Thanks. 谢谢。
bool (Foo::*filter_Function)(Tree* node, std::list<std::string>& arg)
Will give you a member function pointer. 会给你一个成员函数指针。 You pass one with:
你通过一个:
Foo f;
f.filter(&Foo::events_filter,...);
And invoke it with: 并调用它:
(this->*ff)(...); // the parenthesis around this->*ff are important
If you want to be able to pass any kind of function / functor that follows your syntax, use Boost.Function , or if your compiler supports it, use std::function. 如果您希望能够传递遵循语法的任何类型的函数/函子,请使用Boost.Function ,或者如果您的编译器支持它,请使用std :: function。
class Foo{
typedef boost::function<bool(Tree*,std::list<std::string>&)> filter_function;
// rest as is
};
And then pass anything you want. 然后传递你想要的任何东西。 A functor, a free function (or static member function) or even a non-static member function with Boost.Bind or std::bind (again, if your compiler supports it):
一个仿函数,一个自由函数(或静态成员函数),甚至是一个带有Boost.Bind或std :: bind的非静态成员函数(再次,如果你的编译器支持它):
Foo f;
f.do_filter(boost::bind(&Foo::events_filter,&f,_1,_2),...);
//member function pointer is declared as
bool (*Foo::filter_function)(Tree* node, std::list<std::string>& arg);
//Usage
//1. using object instance!
Foo foo;
filter_function = &foo::events_filter;
(foo.*filter_function)(node, arg); //CALL : NOTE the syntax of the line!
//2. using pointer to foo
(pFoo->*filter_function)(node, arg); //CALL: using pFoo which is pointer to Foo
(this->*filter_function)(node, arg); //CALL: using this which is pointer to Foo
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