Pointers for these pointers...?

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  • DirtyClamDigger
    #1

    Pointers for these pointers...?

    Hi Everyone: I'm trying to develop a property list to include as
    metadata about my object classes. i.e. I want each class I'm developing
    to include a PropertyList which will contain ObjectProperty pointers.
    ObjectProperty is a class containing the typeid.name() of a type as
    it's ObjectType as well as an ObjectName and ObjectDescripti on.
    Basically 3 strings of metadata describing each of a class' member
    variables (and hopefully functions) so that the class can report to a
    query from another class what properties it has available for access at
    run time.

    Here is what I have and the error I'm getting:

    // ObjectProperty. hpp
    #pragma once
    #include <string>
    #include <list>
    #include <typeinfo>


    namespace Properties
    {
    template<typena me aProperty> class ObjectProperty
    {
    private:
    std::string PropertyName;
    std::string PropertyType;
    std::string PropertyDescrip tion;

    public:
    ObjectProperty(
    const std::string& _PropertyName,
    const std::string& _PropertyType,
    const std::string& _PropertyDescri ption ):
    PropertyName(_P ropertyName),
    PropertyType(_P ropertyType),
    PropertyDescrip tion(_PropertyD escription){}

    ObjectProperty(
    const std::string& _PropertyName,
    const std::string& _PropertyDescri ption ):
    PropertyName(_P ropertyName),
    PropertyType(ty peid(aProperty) .name()),
    PropertyDescrip tion(_PropertyD escription){}

    ObjectProperty( ):
    PropertyName(),
    PropertyType(ty peid(aProperty) .name()),
    PropertyDescrip tion(){}

    ~ObjectProperty (){}

    const std::string& getPropertyName () const
    {
    return PropertyName;
    }

    const std::string& getPropertyType () const
    {
    return PropertyType;
    }

    const std::string& getPropertyDesc ription() const
    {
    return PropertyDescrip tion;
    }

    void setPropertyName ( const std::string& _PropertyName )
    {
    PropertyName = _PropertyName;
    }

    void setPropertyType ( const std::string& _PropertyType )
    {
    PropertyType = _PropertyType;
    }

    void setPropertyDesc ription( const std::string& _PropertyDescri ption
    )
    {
    PropertyDescrip tion = _PropertyDescri ption;
    }
    };

    // a simple wrapper to have further functionality added
    class PropertyList
    {
    public:
    // will be made private later after I get it working :o)
    std::list<Objec tProperty*> theProperties;

    // public functions such as....
    // void displayProperti es();
    // const list<ObjectProp erty*>& getProperties() ;
    // bool compareProperti es(PropertyList &, PropertyList&);
    // ....
    };

    };

    // ObjectPropertyD river.cpp
    #include <iostream>
    #include "ObjectProperty .hpp"

    using namespace Properties;
    using namespace std;

    int main(void)
    {
    try
    {
    // active code

    PropertyList pl;
    ObjectProperty< char* >* op = new ObjectProperty< char* >("My char*
    Property", "My char* Property Description");
    pl.thePropertie s.push_back(op) ;

    return 0;
    }
    catch(...) // any old exception not already caught
    {
    cerr << "OOooops ... unexpected exception\n";
    }

    }

    Error 1 error C2664: 'std::list<_Ty> ::push_back' : cannot convert
    parameter 1 from 'Properties::Ob jectProperty<aP roperty> *' to
    'Properties::Ob jectProperty *const &' ...\objectprope rtydriver.cpp 15

    compiler is devstudio 8.blah....

    If I'm going about it completely wrong then a pointer in the right
    direction would be helpful, otherwise any suggestions at all are
    welcome....

    TIA,
    LJH.

    Tags: None
    • Artie Gold
      #2
      Re: Pointers for these pointers...?

      DirtyClamDigger wrote:[color=blue]
      > Hi Everyone: I'm trying to develop a property list to include as
      > metadata about my object classes. i.e. I want each class I'm developing
      > to include a PropertyList which will contain ObjectProperty pointers.
      > ObjectProperty is a class containing the typeid.name() of a type as
      > it's ObjectType as well as an ObjectName and ObjectDescripti on.
      > Basically 3 strings of metadata describing each of a class' member
      > variables (and hopefully functions) so that the class can report to a
      > query from another class what properties it has available for access at
      > run time.
      >
      > Here is what I have and the error I'm getting:[/color]

      I'm not entirely clear on what you're doing (and I haven't spent
      sufficient time looking) but I this might help. See below:[color=blue]
      >
      > // ObjectProperty. hpp
      > #pragma once
      > #include <string>
      > #include <list>
      > #include <typeinfo>
      >
      >
      > namespace Properties
      > {
      > template<typena me aProperty> class ObjectProperty
      > {
      > private:
      > std::string PropertyName;
      > std::string PropertyType;
      > std::string PropertyDescrip tion;
      >
      > public:
      > ObjectProperty(
      > const std::string& _PropertyName,
      > const std::string& _PropertyType,
      > const std::string& _PropertyDescri ption ):
      > PropertyName(_P ropertyName),
      > PropertyType(_P ropertyType),
      > PropertyDescrip tion(_PropertyD escription){}
      >
      > ObjectProperty(
      > const std::string& _PropertyName,
      > const std::string& _PropertyDescri ption ):
      > PropertyName(_P ropertyName),
      > PropertyType(ty peid(aProperty) .name()),
      > PropertyDescrip tion(_PropertyD escription){}
      >
      > ObjectProperty( ):
      > PropertyName(),
      > PropertyType(ty peid(aProperty) .name()),
      > PropertyDescrip tion(){}
      >
      > ~ObjectProperty (){}
      >
      > const std::string& getPropertyName () const
      > {
      > return PropertyName;
      > }
      >
      > const std::string& getPropertyType () const
      > {
      > return PropertyType;
      > }
      >
      > const std::string& getPropertyDesc ription() const
      > {
      > return PropertyDescrip tion;
      > }
      >
      > void setPropertyName ( const std::string& _PropertyName )
      > {
      > PropertyName = _PropertyName;
      > }
      >
      > void setPropertyType ( const std::string& _PropertyType )
      > {
      > PropertyType = _PropertyType;
      > }
      >
      > void setPropertyDesc ription( const std::string& _PropertyDescri ption
      > )
      > {
      > PropertyDescrip tion = _PropertyDescri ption;
      > }
      > };
      >
      > // a simple wrapper to have further functionality added
      > class PropertyList
      > {
      > public:
      > // will be made private later after I get it working :o)
      > std::list<Objec tProperty*> theProperties;[/color]
      // ITYM:
      std::list<Objec tProperty<aProp erty>*> theProperties;

      // as ObjectProperty is a templated class[color=blue]
      >
      > // public functions such as....
      > // void displayProperti es();
      > // const list<ObjectProp erty*>& getProperties() ;
      > // bool compareProperti es(PropertyList &, PropertyList&);
      > // ....
      > };
      >
      > };
      >
      > // ObjectPropertyD river.cpp
      > #include <iostream>
      > #include "ObjectProperty .hpp"
      >
      > using namespace Properties;
      > using namespace std;
      >
      > int main(void)
      > {
      > try
      > {
      > // active code
      >
      > PropertyList pl;
      > ObjectProperty< char* >* op = new ObjectProperty< char* >("My char*
      > Property", "My char* Property Description");
      > pl.thePropertie s.push_back(op) ;
      >
      > return 0;
      > }
      > catch(...) // any old exception not already caught
      > {
      > cerr << "OOooops ... unexpected exception\n";
      > }
      >
      > }
      >
      > Error 1 error C2664: 'std::list<_Ty> ::push_back' : cannot convert
      > parameter 1 from 'Properties::Ob jectProperty<aP roperty> *' to
      > 'Properties::Ob jectProperty *const &' ...\objectprope rtydriver.cpp 15
      >
      > compiler is devstudio 8.blah....
      >
      > If I'm going about it completely wrong then a pointer in the right
      > direction would be helpful, otherwise any suggestions at all are
      > welcome....
      >[/color]
      See above.

      HTH,
      --ag


      --
      Artie Gold -- Austin, Texas
      http://goldsays.blogspot.com (new post 8/5)
      http://www.cafepress.com/goldsays
      "If you have nothing to hide, you're not trying!"

        Comment

        • DirtyClamDigger
          #3
          Re: Pointers for these pointers...?

          Thanks, Artie, but that doesn't seem to work either. What is bugging me
          is that if I comment out the push_back call in the code above then it
          compiles and runs fine. I'm simply trying to find a way to have a
          property list associated with each class I create so that I can query
          objects of that class as to the descriptions of their data. i.e. data
          about the data is called 'meta'data. In my mind that means having a
          static list of name/type/description triplets describing the
          datamembers of a class..

          e.g. // this code is just off the top of my head to demo my
          intent...don't expect correctness! :o)

          class aClass{
          public:

          int anInt;
          double aDouble;
          static PropertyList dataProperties;

          //...class def'ns etc...
          void loadProperites( ){
          ObjectProperty* <double> op = new ObjectProperty< double>("aDoubl e", "A
          Double defined for this dummy class);
          dataProperties. push_back(*op);
          }
          };...//end class

          Anyway, I tried your suggestion and it still fetches up with a type
          mismatch error. I guess I'm going to have to sit and think on it a bit
          more....

          Thanks anyway.

          regards,
          LJH

            Comment

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