?explicit instantiation member function of class template

[henkoo@gmail.com]

i want to explicit instantiate a member function of a class template,
and got some error,
can anyone give some advice to correct it?
3x

complier: g++ 3.2

#include <iostream>
#include <string>
using namespace std;

template <class BT> class FilterRangeItem {
public:
bool m_bIsSetLow;
bool m_bIsSetHigh;
bool m_bIsFailed;
BT m_low;
BT m_high;
FilterRangeItem ();
virtual BT _Convert(string );
virtual bool SetFilter(strin g,string);
};

template <class BT>
FilterRangeItem <BT>::FilterRan geItem() {
m_bIsSetLow = m_bIsSetHigh = m_bIsFailed = false;
}

template <class BT>
BT FilterRangeItem <BT>::_Convert( string str) {
BT a;
cout <<"FilterRAngeI tem<BT>::_Conve rt()"<<endl;
return a;
}

template <class BT>
bool FilterRangeItem <BT>::SetFilter (string low, string high) {
if (low.length()>0 ) {
m_low = _Convert(low);
if (!m_bIsFailed) m_bIsSetLow = true;
}
if (high.length() > 0) {
m_high = _Convert(high);
if (!m_bIsFailed) m_bIsSetHigh = true;
}
cout <<"SetFilter finished"<<endl ;
return m_bIsSetFailed;
}

template int FilterRangeItem <int>::_Convert (string str) {
cout <<"FilterRangeI tem<int>::_Conv ert"<<endl;
return 0;
}
template double FilterRangeItem <double>::_Conv ert(string str) {
cout <<"FilterRangeI tem<double>::_C onvert"<<endl;
return 0.0
}

class Filter {
public:
FilterRangeItem <int> iFlt;
FilterRangeItem <double> dFlt;
};

int main(int argc, char* argv[])
{
{
Filter f;
iFlt.SetFilter( "3", "5");
dFlt.SetFilter( "6.0", "9.10");
}
int x;
cin>>x;

return 0;
}

compiler error:
t1.cpp:43: parse error before `{' token
t1.cpp:47: parse error before `{' token
t1.cpp: In function `int main(int, char**)':
t1.cpp:62: `iFlt' undeclared (first use this function)
t1.cpp:62: (Each undeclared identifier is reported only once for each
function
it appears in.)
t1.cpp:63: `dFlt' undeclared (first use this function)

[Neelesh Bodas]

Re: ?explicit instantiation member function of class template


henkoo@gmail.co m wrote:[color=blue]
> i want to explicit instantiate a member function of a class template,
> and got some error,
> can anyone give some advice to correct it?[/color]

Best advice is to understand the compiler-given errors and fix them one
by one.[color=blue]
>
> complier: g++ 3.2
>
> #include <iostream>
> #include <string>
> using namespace std;
>
> template <class BT> class FilterRangeItem {
> public:
> bool m_bIsSetLow;
> bool m_bIsSetHigh;
> bool m_bIsFailed;
> BT m_low;
> BT m_high;[/color]

It is a *very_bad* idea to declare your data members all public.
[color=blue]
> FilterRangeItem ();
> virtual BT _Convert(string );[/color]

Avoid using names that start with an underscore, they are reserved for
implementation.
[color=blue]
> virtual bool SetFilter(strin g,string);
> };[/color]

If you expect the class to be polymorphic (as indicated by virtual
functions), always define a virtual destructor.

[color=blue]
>
> template <class BT>
> FilterRangeItem <BT>::FilterRan geItem() {
> m_bIsSetLow = m_bIsSetHigh = m_bIsFailed = false;
> }[/color]

Use constructor-initialization list instead of assignments in the body
of the constructor.

[...snip...]
[color=blue]
> template int FilterRangeItem <int>::_Convert (string str) {
> cout <<"FilterRangeI tem<int>::_Conv ert"<<endl;
> return 0;[/color]

This is a complete specialization of the member template. Hence you
need to introduce empty angle-brackets after the word template.

template<> int FilterRangeItem <int>::_Convert (string str) {
[color=blue]
> }
> template double FilterRangeItem <double>::_Conv ert(string str) {
> cout <<"FilterRangeI tem<double>::_C onvert"<<endl;
> return 0.0[/color]

Same here.
[color=blue]
> }
>
> class Filter {
> public:
> FilterRangeItem <int> iFlt;
> FilterRangeItem <double> dFlt;
> };
>
> int main(int argc, char* argv[])
> {
> {
> Filter f;
> iFlt.SetFilter( "3", "5");[/color]

Whats that? C++ needs variables to be declared before they are used.
[color=blue]
> dFlt.SetFilter( "6.0", "9.10");[/color]

Same.

Hope this helps.

[Viktor Prehnal]

Re: ?explicit instantiation member function of class template

specialization is done as, in VS.NET otherwise works....

template<> int f(......)


henkoo@gmail.co m wrote:[color=blue]
> i want to explicit instantiate a member function of a class template,
> and got some error,
> can anyone give some advice to correct it?
> 3x
>
> complier: g++ 3.2
>
> #include <iostream>
> #include <string>
> using namespace std;
>
> template <class BT> class FilterRangeItem {
> public:
> bool m_bIsSetLow;
> bool m_bIsSetHigh;
> bool m_bIsFailed;
> BT m_low;
> BT m_high;
> FilterRangeItem ();
> virtual BT _Convert(string );
> virtual bool SetFilter(strin g,string);
> };
>
> template <class BT>
> FilterRangeItem <BT>::FilterRan geItem() {
> m_bIsSetLow = m_bIsSetHigh = m_bIsFailed = false;
> }
>
> template <class BT>
> BT FilterRangeItem <BT>::_Convert( string str) {
> BT a;
> cout <<"FilterRAngeI tem<BT>::_Conve rt()"<<endl;
> return a;
> }
>
> template <class BT>
> bool FilterRangeItem <BT>::SetFilter (string low, string high) {
> if (low.length()>0 ) {
> m_low = _Convert(low);
> if (!m_bIsFailed) m_bIsSetLow = true;
> }
> if (high.length() > 0) {
> m_high = _Convert(high);
> if (!m_bIsFailed) m_bIsSetHigh = true;
> }
> cout <<"SetFilter finished"<<endl ;
> return m_bIsSetFailed;
> }
>
> template int FilterRangeItem <int>::_Convert (string str) {
> cout <<"FilterRangeI tem<int>::_Conv ert"<<endl;
> return 0;
> }
> template double FilterRangeItem <double>::_Conv ert(string str) {
> cout <<"FilterRangeI tem<double>::_C onvert"<<endl;
> return 0.0
> }
>
> class Filter {
> public:
> FilterRangeItem <int> iFlt;
> FilterRangeItem <double> dFlt;
> };
>
> int main(int argc, char* argv[])
> {
> {
> Filter f;
> iFlt.SetFilter( "3", "5");
> dFlt.SetFilter( "6.0", "9.10");
> }
> int x;
> cin>>x;
>
> return 0;
> }
>
> compiler error:
> t1.cpp:43: parse error before `{' token
> t1.cpp:47: parse error before `{' token
> t1.cpp: In function `int main(int, char**)':
> t1.cpp:62: `iFlt' undeclared (first use this function)
> t1.cpp:62: (Each undeclared identifier is reported only once for each
> function
> it appears in.)
> t1.cpp:63: `dFlt' undeclared (first use this function)
>[/color]

[henkoo@gmail.com]

Re: ?explicit instantiation member function of class template

thanks a lot.

also i'd found some snippet on specialization without <> like:

template class vector<int>;

what is it?

p.s. i found your reply after deleting my original post

[henkoo@gmail.com]

Re: ?explicit instantiation member function of class template

thanks a lot.

also i'd found some snippet on specialization without <> like:

template class vector<int>;

what is it?

p.s. i found your reply after deleting my original post

Neelesh Bodas wrote:[color=blue]
> henkoo@gmail.co m wrote:[color=green]
> > i want to explicit instantiate a member function of a class template,
> > and got some error,
> > can anyone give some advice to correct it?[/color]
>
> Best advice is to understand the compiler-given errors and fix them one
> by one.[color=green]
> >
> > complier: g++ 3.2
> >
> > #include <iostream>
> > #include <string>
> > using namespace std;
> >
> > template <class BT> class FilterRangeItem {
> > public:
> > bool m_bIsSetLow;
> > bool m_bIsSetHigh;
> > bool m_bIsFailed;
> > BT m_low;
> > BT m_high;[/color]
>
> It is a *very_bad* idea to declare your data members all public.
>[color=green]
> > FilterRangeItem ();
> > virtual BT _Convert(string );[/color]
>
> Avoid using names that start with an underscore, they are reserved for
> implementation.
>[color=green]
> > virtual bool SetFilter(strin g,string);
> > };[/color]
>
> If you expect the class to be polymorphic (as indicated by virtual
> functions), always define a virtual destructor.
>
>[color=green]
> >
> > template <class BT>
> > FilterRangeItem <BT>::FilterRan geItem() {
> > m_bIsSetLow = m_bIsSetHigh = m_bIsFailed = false;
> > }[/color]
>
> Use constructor-initialization list instead of assignments in the body
> of the constructor.
>
> [...snip...]
>[color=green]
> > template int FilterRangeItem <int>::_Convert (string str) {
> > cout <<"FilterRangeI tem<int>::_Conv ert"<<endl;
> > return 0;[/color]
>
> This is a complete specialization of the member template. Hence you
> need to introduce empty angle-brackets after the word template.
>
> template<> int FilterRangeItem <int>::_Convert (string str) {
>[color=green]
> > }
> > template double FilterRangeItem <double>::_Conv ert(string str) {
> > cout <<"FilterRangeI tem<double>::_C onvert"<<endl;
> > return 0.0[/color]
>
> Same here.
>[color=green]
> > }
> >
> > class Filter {
> > public:
> > FilterRangeItem <int> iFlt;
> > FilterRangeItem <double> dFlt;
> > };
> >
> > int main(int argc, char* argv[])
> > {
> > {
> > Filter f;
> > iFlt.SetFilter( "3", "5");[/color]
>
> Whats that? C++ needs variables to be declared before they are used.
>[color=green]
> > dFlt.SetFilter( "6.0", "9.10");[/color]
>
> Same.
>
> Hope this helps.[/color]

[henkoo@gmail.com]

Re: ?explicit instantiation member function of class template

thanks a lot.

also i'd found some snippet on specialization without <> like:

template class vector<int>;

what is it?

p.s. i found your reply after deleting my original post

Neelesh Bodas wrote:[color=blue]
> henkoo@gmail.co m wrote:[color=green]
> > i want to explicit instantiate a member function of a class template,
> > and got some error,
> > can anyone give some advice to correct it?[/color]
>
> Best advice is to understand the compiler-given errors and fix them one
> by one.[/color]
[color=blue][color=green]
> > template <class BT>
> > FilterRangeItem <BT>::FilterRan geItem() {
> > m_bIsSetLow = m_bIsSetHigh = m_bIsFailed = false;
> > }[/color]
>
> Use constructor-initialization list instead of assignments in the body
> of the constructor.
>
> [...snip...]
>[color=green]
> > template int FilterRangeItem <int>::_Convert (string str) {
> > cout <<"FilterRangeI tem<int>::_Conv ert"<<endl;
> > return 0;[/color]
>
> This is a complete specialization of the member template. Hence you
> need to introduce empty angle-brackets after the word template.
>
> template<> int FilterRangeItem <int>::_Convert (string str) {
>[color=green]
> > }
> > template double FilterRangeItem <double>::_Conv ert(string str) {
> > cout <<"FilterRangeI tem<double>::_C onvert"<<endl;
> > return 0.0[/color]
>
> Same here.
>[color=green]
> > }[/color][/color]
[color=blue]
>
> Same.
>
> Hope this helps.[/color]