Re: Class hierarchy generated from a template

From:
"Victor Bazarov" <v.Abazarov@comAcast.net>
Newsgroups:
comp.lang.c++.moderated
Date:
30 Apr 2006 12:56:15 -0400
Message-ID:
<3uidnashtJqT4c7ZnZ2dnUVZ_smdnZ2d@comcast.com>
Dimitar wrote:

What is wrong with the following:

template<size_t size> class X;


'size_t' is undefined. You need to add '#include <cstddef>' before
this line, for example. Otherwise, change 'size_t' to 'unsigned'.

template<>
class X<0> {};

template<>
class X<1>
{
public:
 void M(const char (&x)[1]) {}
};

template<size_t size>
class X : public X<size - 1>
{
public:
 void M(const char (&x)[size]) {}


This function 'M' hides the 'M' in the base class. Please add

    using X<size-1>::M;

here.

};

Sample use would be:

char arr[3] = "ab";
X<4> x;
x.M(arr);

However this does not compile with MS VC7. If arr has size 4 then it
compiles.


Correct. You need to fix it as I suggested above.

Am I trying to do something that is not possible - for example the
line "class X : public X<size - 1>"? If this is not valid I would
expect that it should not compile at all then (have not had chance to
test with gcc) or at least give some warning.

And No, I can not use vector, or string, or anything more inteligent
than C-array (there are reasons why, but they are not related to the
question in this post)


V
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