Thread: Mixing templates and inheritance, and the damage caused ;)

I get like 30 errors when I try to compile the following. It is intended to be used something like this.

Code:

Parser parser("inputfile.txt");
parser.addAction("PlayerWeight",new stdRead<float>(someFloat));
parser.addAction("XWidth",new readAndCheck<int>(xWidth, xWidthChanged);
parser.read();

if (!xWidthChanged) {
    xWidth=DEFAULT_X_VALUE;
}

inputfile.txt

PlayerWeight=2.1e2
xWidth=50

I can't understand any of the compiler error messages . When trying to extend a class with a template, how does one say, derived<T> inherits base<T>? I have a feeling that is the root of my problem.

Code:

//Parse.h

// /*

#ifndef PARSE_H_
#define PARSE_H_

#include <string>
#include <fstream>
#include <map>

using namespace std;

class ParseAction;

typedef map<const string, ParseAction*> ActionMap_t;

class Parser {
public:
       Parser(istream &inputFile);
       ~Parser();
       
       /* NOTE: calls to this addAction() must pass a dynamic ParseAction* via new, 
          else the destructor will cause a crash */
       void addAction(const string& identifier, ParseAction* action);      
       void read();
private:
        ActionMap_t actionMap;
        ifstream& input;        
};

class ParseAction {
public:
      virtual void getValue(istream& input)=0;
};
      
template <class T> 
class StdRead: public ParseAction {
public:
       StdRead(T& object);
       virtual void getValue(istream& input);
protected:
        T& obj;            
};

template <class T>
class  ReadAndCheck: public StdRead {
public:
       ReadAndCheck(T& obj, bool& objectSet_);
       virtual void getValue(istream& input);
protected:
          bool& objectSet;
};

template <class T>
class ReadAndMult: public StdRead {
public:
       ReadAndMult(T& object, T mult);
       virtual void getValue(istream& input);
protected:
          T multiplier;
};

#endif // ifndef PARSE_H_

// */

The errors are the following.

1 parsetestmain.cpp
c:\code\c++\gravitysim\parse.h:47: parse error before `{'

50 parse.h
virtual outside class declaration

51 parse.h
parse error before `protected'

56 parse.h
parse error before `{'

59 parse.h
virtual outside class declaration

60 parse.h
parse error before `protected'

3 parse.cpp
c:\code\c++\gravitysim\parse.h:47: parse error before `{'

50 parse.h
virtual outside class declaration

51 parse.h
parse error before `protected'

56 parse.h
parse error before `{'

59 parse.h
virtual outside class declaration

60 parse.h
parse error before `protected'

5 parse.cpp
prototype for `Parser::Parser(ifstream &)' does not match any in class `Parser'

30 parse.h
candidates are: Parser::Parser(const Parser &)

20 parse.h
Parser::Parser(istream &)

12 parse.cpp
no match for `_Rb_tree_iterator<pair<const basic_string<char,string_char_traits<char>,__defau lt_alloc_template<false,0> >,ParseAction *>,pair<const basic_string<char,string_char_traits<char>,__defau lt_alloc_template<false,0> >,ParseAction *> &,pair<const basic_string<char,string_char_traits<char>,__defau lt_alloc_template<false,0> >,ParseAction *> *> & < _Rb_tree_iterator<pair<const basic_string<char,string_char_traits<char>,__defau lt_alloc_template<false,0> >,ParseAction *>,pair<const basic_string<char,string_char_traits<char>,__defau lt_alloc_template<false,0> >,ParseAction *> &,pair<const basic_string<char,string_char_traits<char>,__defau lt_alloc_template<false,0> >,ParseAction *> *>'

52 parse.cpp
syntax error before `::'

57 parse.cpp
syntax error before `::'

62 parse.cpp
syntax error before `::'

68 parse.cpp
syntax error before `::'

70 parse.cpp
ANSI C++ forbids declaration `objectSet' with no type

71 parse.cpp
parse error before `}'

57 parse.cpp
syntax error before `::'

62 parse.cpp
syntax error before `::'

68 parse.cpp
syntax error before `::'

70 parse.cpp
ANSI C++ forbids declaration `objectSetеä

incremental testing...

code... compile... pray... repeat...

break it down into more simple pieces with minimal interactions... then build up...

This one hit me as I was scrolling your code:

Code:

template <class T>
class  ReadAndCheck: public StdRead {

When you derive from template, you must specify its type:

Code:

template <class T>
class  ReadAndCheck: public StdRead<T> {