pgplot::HandleOfConst< X > Class Template Reference
Base class for handles. More...
#include <pghandle.h>
Inheritance diagram for pgplot::HandleOfConst< X >:
Public Types | |
Typedefs for class template HandleOfConst. | |
| |
| typedef X | Tvalue |
| typedef X * | Tpointer |
| typedef X & | Treference |
| typedef const X * | Tpointer_to_const |
| typedef const X & | Treference_to_const |
| typedef HandleOfConst< Tvalue > | Tcontainer |
| typedef Tcontainer | Tcontainer_of_const |
| typedef Tcontainer_of_const | Tcoc |
Public Member Functions | |
| ~HandleOfConst () | |
| Destructor that takes care of reference count. More... | |
| template<class Y > | |
| Tcontainer & | operator= (const HandleOfConst< Y > &h) |
| Assignement operator that provide transparency for inheritance. More... | |
Constructors | |
| HandleOfConst () | |
| Default constructor if class X provides one too. More... | |
| HandleOfConst (Treference_to_const x) | |
| Constructor to initialize the handle. More... | |
| template<class Y > | |
| HandleOfConst (const HandleOfConst< Y > &h) | |
| Copy constructor that provides transparency for inheritance. More... | |
Read access operators | |
| Tpointer_to_const | operator-> () const |
| Read access operator with pointer semantics. More... | |
| Treference_to_const | operator* () const |
| Read access operator with pointer semantics. More... | |
Protected Member Functions | |
Write access operators must be protected | |
| Tpointer | pointer () const |
| expose the pointer to derived classes More... | |
| Treference | reference () const |
| expose the object to derived classes More... | |
Private Attributes | |
| Tpointer | Mpointer |
| internal pointer to the handled object More... | |
| int * | Mpcount |
| reference counter More... | |
Friends | |
| template<class Y > | |
| class | HandleOfConst |
| friend declaration to other Handle templates is essential for inheritance transparency. More... | |
Detailed Description
template<class X>
class pgplot::HandleOfConst< X >
Base class for handles.
The base class is necessary to promise constness for values that are passed around using handles. Consider a code that uses a handle to pass the contents of a class of type A as defined by
class A {
...
};
Handle<A> a;
A function sample can accept a handle providing access to the values of type A but promising not to changes these values if declared
or briefly
Declaring the function
void sample(const Handle<A>& h);
is not sufficient, since this only promises constness of the handle but not of the values that can be accessed through the handle.
- See also
- Example code is available in pgtestxx.cc
- Therein example code is available in functions testhandle() and testhandlefunction()
Definition at line 85 of file pghandle.h.
The documentation for this class was generated from the following file:
