Forward declarations

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JoNinty - 17 May 2004 18:01 GMT

Class S contains a pointer to class main
Class main contains and instance of class
I therefore include a forward reference in S of main
The catch is I want to call a method in main from s and if I do this I get an erro
use of undefined type 'Main'
So how can I call a method in main from S and if I cant whats the point in being able to store a pointer to it?

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Rudy Ray Moore - 17 May 2004 18:38 GMT

> I therefore include a forward reference in S of main.

This should be in the .h file

> The catch is I want to call a method in main from s and if I do this I get an error

No problem.

Try this:
1) in s.cpp: #include<main.h>
2) in main.cpp: #inlcude<s.h>

Do not try this:
1) in s.h: #include<main.h>
2) in main.h: #inlcude<s.h>

Rudy

> Class S contains a pointer to class main.
> Class main contains and instance of class S
> I therefore include a forward reference in S of main.
> The catch is I want to call a method in main from s and if I do this I get an error
> use of undefined type 'Main'.
> So how can I call a method in main from S and if I cant whats the point in being able to store a pointer to it?

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JoNinty - 18 May 2004 10:01 GMT

Thank you. A well placed #include solved this
You never see this type of thing in books do you?

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Matt Osborn - 18 May 2004 14:13 GMT

Large-Scale C++ Software Design by John Lakos

> Thank you. A well placed #include solved this !
> You never see this type of thing in books do you?

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mccoyn - 17 May 2004 19:46 GMT

You can't define the function inline. The following should work

class main

class S
main* m
void foo()
}

class main
S s
int i

void S::foo()
do_something(m->i)
}

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Forward declarations

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