casacore::PtrHolder< T > Class Template Reference

Hold and delete pointers not deleted by object destructors. More...

#include <PtrHolder.h>

Public Member Functions
	PtrHolder ()
	The default constructor uses a null pointer. More...
	PtrHolder (T *pointer, Bool isCArray=False)
	Construct a PtrHolder from a pointer which MUST have been allocated from new, since the destructor will call delete on it. More...
	~PtrHolder ()
void	set (T *pointer, Bool isCarray=False, Bool deleteCurrentPtr=True)
	Set the pointer to a new value. More...
void	clear (Bool deleteCurrentPtr=True)
	Set the current pointer to null; if deletePtr is True (the default), then the current pointer is deleted first. More...
T *	ptr ()
	Release the pointer for use. More...
const T *	ptr () const
	operator T * ()
	Attempt to automatically release a pointer when required. More...
	operator T * () const

Detailed Description

template<class T>
class casacore::PtrHolder< T >

Hold and delete pointers not deleted by object destructors.

Intended use:

Public interface

Review Status

Reviewed By:

troberts

Date Reviewed:

1995/07/29

Test programs:

tPtrHolder

Prerequisite

• module Exceptions

Synopsis

PtrHolders hold allocated pointers which should be deleted when an exception is thrown. Exceptions only call destructors of objects. Thus, for example, storage allocated in a global function (outside of an object)is not deleted. A PtrHolder solves this problem: it merely holds the pointer and deletes it when it is destroyed itself, e.g. when an exception is thrown or when the function exits normally.

Example

void func(Int *ptr); // some other function that takes a pointer
//..\.
// True below means it's an array, False (the default) would mean
// a singleton object.
PtrHolder<Int> iholder(new Int[10000], True);
func(iholder);                           // converts automatically to ptr
(iholder.ptr() + 5) = 11;                // use pointer explicitly
some_function_that_throws_exception();   // pointer is deleted

Motivation

Avoid leaks when throwing/catching exceptions.

To Do

• Use the autoptr class from the Standard Library

Definition at line 81 of file PtrHolder.h.

Constructor & Destructor Documentation

template<class T>

casacore::PtrHolder< T >::PtrHolder

(

)

The default constructor uses a null pointer.

template<class T>

casacore::PtrHolder< T >::PtrHolder	(	T *	pointer,
		Bool	isCArray = False
	)

Construct a PtrHolder from a pointer which MUST have been allocated from new, since the destructor will call delete on it.

If the pointer is to an array, i.e. allocated with operator new[], then isCarray should be set to True. (This parameter is required because C-arrays need to be deleted with delete[].)

After the pointer is placed into the holder, the user should not manually delete the pointer; the PtrHolder object will do that, unless set() or clear() is called with deleteCurrentPtr set to False. The pointer must also only be put into one holder to avoid double deletion.

template<class T>

casacore::PtrHolder< T >::~PtrHolder

(

)

Member Function Documentation

template<class T>

void casacore::PtrHolder< T >::clear

(

Bool

deleteCurrentPtr = True

)

Set the current pointer to null; if deletePtr is True (the default), then the current pointer is deleted first.

template<class T>

casacore::PtrHolder< T >::operator T * ( )

inline

Attempt to automatically release a pointer when required.

If the compiler can't figure it out, you can use the ptr() member function directly.

Definition at line 124 of file PtrHolder.h.

template<class T>

casacore::PtrHolder< T >::operator T * ( ) const

inline

Definition at line 125 of file PtrHolder.h.

template<class T>

T* casacore::PtrHolder< T >::ptr ( )

inline

Release the pointer for use.

Definition at line 117 of file PtrHolder.h.

template<class T>

const T* casacore::PtrHolder< T >::ptr ( ) const

inline

Definition at line 118 of file PtrHolder.h.

template<class T>

void casacore::PtrHolder< T >::set	(	T *	pointer,
		Bool	isCarray = False,
		Bool	deleteCurrentPtr = True
	)

Set the pointer to a new value.

If deleteCurrentPtr is True (the default), then delete the existing pointer first. If isCarray is True, then the new pointer is assumed to have been allocated with new[].

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The documentation for this class was generated from the following file:

• casa/Utilities/PtrHolder.h