Newsgroups: comp.os.msdos.djgpp
Followup-To: poster
From: frenchc AT cadvision DOT com (Calvin French)
Subject: Re: Inheritence lost in multiple files
References: <6lk7np$pld$2 AT News DOT Dal DOT Ca>
Date: Wed, 10 Jun 1998 00:28:01 GMT
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Message-ID: <357dd21b.0@news.cadvision.com>
Organization: CADVision Development Corporation (http://www.cadvision.com/)
Lines: 101
To: djgpp AT delorie DOT com
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>//In foo.h
>
>class foo
>{
>        public: foo();
>        protected:
>                        int foosint;
>};

Good so far...

>//in foo.cpp
>
>#include "foo.h"
>
>foo::foo()
>{
>        foosint = 0;
>}

Not really important, but a "better" (and of course better is hugely relative) 
way to do this is:

foo::foo()
   : foosint(0)
{
};

Why is this better? Well pretend you had an element in class foo which did not 
have a default constructor. For instance bas( char* S ). You would want to 
initialize bas with some string then, inside foos constructor, but this will 
not work as you expect:

foo::foo()
{
   mybas = bas( "hi" );
};

Because what happens is the compiler stops when it sees it can't generate 
bas() without a string as an argument. And it of course must generate objects 
before you can use any code which manipulates them. So you either have to 
write a default ctor for bas (actually not a bad idea, I usually/almost always 
do anyways) or do this:

foo::foo()
   : mybas( "hi" )
{
};

Er, but anyways, that's nothing to do with what you were asking...

>//in bar.h
>
>#include "foo.h"
>
>class bar : public foo
>{
>        public: foo();
>};

Why are you overloading foo()? Don't you mean bar()? I think that is your 
problem. foo() gets called automatically when you create bar() due to the 
inheritance (well I *think*, best to check it out, but I'm quite sure, grr so 
many things to remember w/ C++)

>//in bar.cpp
>
>#include "bar.h"
>
>bar::bar()
>{
>        foosint = 4;
>}
>
>This creates the error:
>
>Error: member 'foosint' is a protected member of class 'foo';
>
>Somewhere in the multiple files, the compiler lost the inheritence.

Well, I expect what is happening is the compiler does not see bar::bar() as a 
function of bar, so it doesn't pick up on the inheritance (i.e., it just sees 
it as another function, and possibly namespaces make this kind of thing 
perfectly legal, I'm not really sure) But you have the inheritance right. And 
don't worry, djgpp will not "lose" inheritance in multiple files, though you 
may run into trouble yet there... Let me know if that doesn't fix it,

- Calvin -

>By the way, I use DJGPP w/ RHIDE.
>
>Any help welcome.
>

---

http://www.cadvision.com/frenchc/                  (Wig out, peeps.)
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