Re: how to implement MAP<std::string,TYPE>

From:

tmk124@gmail.com

Newsgroups:

comp.lang.c++.moderated

Date:

31 Aug 2006 20:45:36 -0400

Message-ID:

<1157060299.006617.73610@b28g2000cwb.googlegroups.com>

Oscar wrote:

class CA
{
};

class CB
{
};

<"A", TYPE_OF_CA>,
<"B",TYPE_OF_CB>.

and then i wan to use the key string "A" to get the type TYPE_OF_CA
,that is CA.
how to implement it ?

  If all these classes inherit from the same base class, you can use a
map from string to ptrs to representative objects of each class. This
can serve as a good replacement for your need of type introspection.

class CBase
{
......
  // to return results of default constructor
  virtual CBase * new_obj() = 0;
   // add more prototypes for other constructors
......
  virtual const char *name() = 0; // type name
};

class CA : public CBase
{
...
};

class CB : public CBase
{
......
};

std::map<std::string, CBase *> name_to_type;

  After filling the map, you would be able to use these objects, call
their common methods, create objects of the same type, query the name
of their type etc.

  Michael

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