Klaas Vantournhout wrote in message
<4560e845$0$1120$ba620e4c@news.skynet.be>...
Quote:
>Hi,
>
>Recently I obtained a problem with virtual inheritance when implementing
>it in multiple files. To present the problem I have included at the
>bottom of this post the code of the 4 files. I show results with the
>gnu compiler but i have the same results with the intel compiler.
>
>file1.cpp compiles without a problem, the problem occurs when compiling
>file2.cpp. It complains about not finding the constructor of the class
>base.
>
>[klaas@blackdwarf cpptest]$ g++ -c -Wall file2.cpp
>file2.cpp: In constructor 'doublederived::doublederived(int)':
>file2.cpp:3: error: no matching function for call to 'base::base()'
>file1.hpp:3: note: candidates are: base::base(int)
>file1.hpp:1: note: base::base(const base&)
>
>When derived does not virtual inherit base, this does not give a
>problem. Is there a reason why this is not working?
>
>Regards
>Klaas
>
>// file1.hpp
>class base {
public:
base(int);
>};
>
>class derived : public virtual base {
public:
derived(int);
>};
>
>// file1.cpp
>#include <iostream>
>#include "file1.hpp"
>base::base(int a) { std::cout << a << std::endl;}
>derived::derived(int a) : base(a) { }
>
>// file2.hpp
>#include "file1.hpp"
>class doublederived : public derived {
public:
doublederived(int);
>};
>
>// file2.cpp
>#include "file2.hpp"
>doublederived::doublederived(int a) : derived(a) { }
I'm not real sharp on this one. I looked at Eckel's and found this (in
diamond example):
class Left : virtual public Top { public: <snip>
Left(int m, int n) : Top(m) { y = n; }
};
class Right : virtual public Top { public: <snip>
Right(int m, int n) : Top(m) { z = n; }
};
class Bottom : public Left, public Right {
int w;
public:
Bottom(int i, int j, int k, int m)
: Top(i), Left(0, j), Right(0, k) { w = m; }
};
Note how, even though Bottom did not directly derive from Top, it was still
initialised in Bottom.
So, maybe try(?):
doublederived::doublederived(int a) : base(a), derived(a) { }
Makes since to me because your error is in looking for a base default
constructor, instead of using your defined constructor.
I'm just guessing at this, but, it shouldn't hurt to try it.
I tried it (in a single file) and it worked.
--
Bob R
POVrookie
