Pass and store static function pointer in constructor

Question

I have a class Foo.

class Foo
{
public:
    int(_bar)(const int);

    Foo(int(bar)(const int))
    {
        _bar = bar;
    }
};

I am trying to pass in a pointer to a static function on creation, and retain that in the class so I can call it later.

I am getting an error of...

error C2659: '=' : function as left operand

...but I don't understand why.

Can anyone please advise?

Drax · Accepted Answer · 2014-10-06 12:46:25Z

2

Function:

int(_bar)(const int);

Function pointer:

int(*_bar)(const int);

You just forgot the *

answered Oct 6, 2014 at 12:46

Drax

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5 Comments

Beakie Over a year ago

Thanks. But why is this not needed on the param?

Drax Over a year ago

It is needed if you want to take a function pointer as a parameter, the error just happens to occur on the member because you are trying to assign to it, which you can do with a function pointer but not with a function (if that even makes sense).

Beakie Over a year ago

So is Foo(int(bar)(const int)) invalid as a constructor definition if I were to pass the method like so: Foo(&someStaticFunc);

Beakie Over a year ago

...because it does compile?

Drax Over a year ago

Well interestingly enough, in a parameter declaration contexte it seems you can assign a parameter of type function when you call the function taking that parameter, it does probably act as a function pointer, but in other contexts (within a class, function, or the global scope) that does not work.

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