casa::PtrHolder< T > Class Template Reference
[Utilities]

#include <PtrHolder.h>

Collaboration diagram for casa::PtrHolder< T >:

[legend]List of all members.

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Detailed Description

template<class T>
class casa::PtrHolder< T >

Hold and delete pointers not deleted by object destructors.

Intended use:

Part of API

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.

Public Member Functions
	PtrHolder ()
	The default constructor uses a null pointer.
	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.
	~PtrHolder ()
void	set (T *pointer, Bool isCarray=False, Bool deleteCurrentPtr=True)
	Set the pointer to a new value.
void	clear (Bool deleteCurrentPtr=True)
	Set the current pointer to null; if deletePtr is True (the default), then the current pointer is deleted first.
Bool	isCArray () const
	See if the pointer points to a C-array.
T *	ptr ()
	Release the pointer for use.
const T *	ptr () const
	operator T * ()
	Attempt to automatically release a pointer when required.
	operator const T * () const
Private Member Functions
	PtrHolder (const PtrHolder< T > &other)
PtrHolder< T > &	operator= (const PtrHolder< T > &other)
void	delete_pointer_if_necessary ()
Private Attributes
T *	ptr_p
Bool	isCarray_p

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Constructor & Destructor Documentation

template<class T>

casa::PtrHolder< T >::PtrHolder

(

)

The default constructor uses a null pointer.

template<class T>

casa::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>

casa::PtrHolder< T >::~PtrHolder

(

)

template<class T>

casa::PtrHolder< T >::PtrHolder

(

const PtrHolder< T > &

other

)

[private]

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Member Function Documentation

template<class T>

void casa::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[].

template<class T>

void casa::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>

T* casa::PtrHolder< T >::ptr

(

)

[inline]

Release the pointer for use.

Definition at line 117 of file PtrHolder.h.

template<class T>

const T* casa::PtrHolder< T >::ptr

(

)

const [inline]

Definition at line 118 of file PtrHolder.h.

template<class T>

casa::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 125 of file PtrHolder.h.

References casa::PtrHolder< T >::ptr_p.

template<class T>

casa::PtrHolder< T >::operator const T *

(

)

const [inline]

Definition at line 126 of file PtrHolder.h.

References casa::PtrHolder< T >::ptr_p.

template<class T>

Bool casa::PtrHolder< T >::isCArray

(

)

const [inline]

See if the pointer points to a C-array.

Definition at line 130 of file PtrHolder.h.

template<class T>

PtrHolder<T>& casa::PtrHolder< T >::operator=

(

const PtrHolder< T > &

other

)

[private]

template<class T>

void casa::PtrHolder< T >::delete_pointer_if_necessary

(

)

[private]

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Member Data Documentation

template<class T>

T* casa::PtrHolder< T >::ptr_p [private]

Definition at line 144 of file PtrHolder.h.

Referenced by casa::PtrHolder< T >::operator const T *(), casa::PtrHolder< T >::operator T *(), and casa::PtrHolder< casa::Measure >::ptr().

template<class T>

Bool casa::PtrHolder< T >::isCarray_p [private]

Definition at line 146 of file PtrHolder.h.

Referenced by casa::PtrHolder< casa::Measure >::isCArray().

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

• casa/implement/Utilities/PtrHolder.h

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