Re: About class constructores with templates

From:

Pete Becker <pete@versatilecoding.com>

Newsgroups:

comp.lang.c++

Date:

Fri, 16 Nov 2007 19:24:57 -0500

Message-ID:

<2007111619245716807-pete@versatilecodingcom>

On 2007-11-16 18:05:49 -0500, "parag_paul@hotmail.com"
<parag_paul@hotmail.com> said:

hi All ,

I am giving the pseudo code about the problem I am talking about .

I have a class hiearchy which looks like this.

class A;

template <class X1, class X2> class B : public A{}

template <class X3> class C: public B<Xreal1, Xreal2>;

Now is it necessary to put the following statement before the line
above like the following

template <Xreal1, Xreal2> class B;
Anyway, the line "template <class X3> class C: public B<Xreal1,
Xreal2>;" is already showing the path to this hierarhcy,
And also, why do that have to instantiate the class B when you are
talking about the class C.

Since I am getting g++ compilation errors due to it.

I am not able to give the code out as it is too sphegtti type and get
some people confused ( like I did )

The pseudo code should help I guess

No, it doesn't help, because it's not at all clear what's real and
what's pseudo, nor did you mention what the error you got was. The
obvious problems are: Xreal1 and Xreal2 are neither declared nor
defined, so you can't use those names to instantiate B. And since A is
declared but not defined, you can't use it as the name of a base class.

As ever, write a small example that produces the problem that you're
running into.

--
Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com) Author of "The
Standard C++ Library Extensions: a Tutorial and Reference
(www.petebecker.com/tr1book)