Quote
"Christian Lotze" <_chrissi...@hotmail.com> wrote in message
news:b2a5c2$spc$03$1@news.t-online.com...
Quote
> Hello,
> Problem:
> Type of object (TButton, TEdit,...) ist given as a variable
> (TypeName:AnsiString). How can i create such an object
> [TypeName].Create.... (can only work with similar objects, derived from
> TWinControl)
> Solution ????????
> other than case-switch.....!
Well, you are talking about a factory. There are many ways to do this. You
should read about this in the GoF Design Patterns book for some background.
One approach is to create a map of factories, something similar to this...
#include <memory>
#include <map>
class Abstract_TWinControl_Factory
: public TComponent
{
public:
__fastcall Abstract_TWinControl_Factory(
TComponent * owner = 0)
: TComponent(owner)
{
}
__fastcall virtual ~Abstract_TWinControl_Factory()
{
}
virtual TWinControl * create() = 0;
template <class TYPE>
class Specific_TWinControl_Factory
: public Abstract_TWinControl_Factory
{
public:
Specific_TWinControl_Factory(
TComponent * owner = 0)
: Abstract_TWinControl_Factory(owner)
{
}
virtual TWinControl * create()
{
std::auto_ptr<TWinControl> control(new TYPE(this));
return control.release();
}
class TWinControl_Factory
: public TComponent
{
public:
__fastcall TWinControl_Factory(
TComponent * owner = 0)
: TComponent(owner)
{
factories_["TButton"] = new Specific_TWinControl_Factory<TButton>(this);
factories_["TEdit"] = new Specific_TWinControl_Factory<TEdit>(this);
}
TWinControl * create(
AnsiString const & type_name)
{
Factories::iterator iter(factories_.find(type_name));
if (iter == factories_.end())
{
return 0;
}
return iter->second->create();
}
private:
typedef std::map<AnsiString, Abstract_TWinControl_Factory*> Factories;
Factories factories_;
