NetNews Usenet Archive 1992 #30/NN_1992_30.iso/spool/comp/lang/cplus/18005

Text File | 1992-12-15 | 1.9 KB | 56 lines

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From: [e-mail] (Douglas Scott)
Newsgroups: comp.lang.c++
Subject: Calling a member functn via ptr passed as arg to another functn
Message-ID: <[e-mail]>
Date: 15 Dec 92 04:46:35 GMT
Sender: [e-mail]
Organization: Center for Computer Music Research and Composition, UCSB
Lines: 45

Here is a very much simplified case of what I wish to do:

class Object;    // to allow typedef
typedef int (*Object::InternalFun)(int); // or close to this...

class Object {
    int internalFunctionA(int i);
    int internalFunctionB(int i);

    int anotherFunction(int x, InternalFun funptr);
public:
    int pubFunA(int x) { return anotherFunction(x, internalFunctionA); }
    int pubFunB(int x) { return anotherFunction(x, internalFunctionB); }
};

// trivial cases of these...

int Object::internalFunctionA(int i) { return i * 5; }

int Object::internalFunctionB(int i) { return i * 6; }

int Object::anotherFunction(int x, InternalFun funptr) {
    return (*funptr)(x);    // this is obviously wrong
}

What I wish to do is create a series of public functions that all call a
single private function, with the difference being that pointers to various
other internal functions are passed as the second argument.

I dont have my ARM handy, so I may have the declaration of the typedef wrong,
but my question relates to the final function definition:

How do I call funptr within anotherFunction()?  Something like:

this->(*funptr)(x) ??  (*this->funptr)(x) ??

-- perhaps??  I have not been able to come up with the correct one yet.

Thank you very much in advance.

--
Douglas Scott                              [phone]
Center for Computer Music Research and Composition
University of California, Santa Barbara
Internet: (NeXTMail ok)   <[e-mail]>