QScopedValueRollback< T > Class Template Reference

The QScopedValueRollback class resets a variable to its previous value on destruction. More...

#include <qscopedvaluerollback.h>

Public Functions
void	commit ()
	Updates the previous value of the managed variable to its current value. More...
	QScopedValueRollback (T &var)
	Stores the previous value of var internally, for revert on destruction. More...
	~QScopedValueRollback ()
	Assigns the previous value to the managed variable. More...

Properties
T	oldValue
T &	varRef

Detailed Description

template<typename T>
class QScopedValueRollback< T >

The QScopedValueRollback class resets a variable to its previous value on destruction.

Since

4.8

The QScopedAssignment class can be used to revert state when an exception is thrown without needing to write try-catch blocks.

It can also be used to manage variables that are temporarily set, such as reentrancy guards. By using this class, the variable will be reset whether the function is exited normally, exited early by a return statement, or exited by an exception.

The template can only be instantiated with a type that supports assignment.

See also

QScopedPointer

Definition at line 52 of file qscopedvaluerollback.h.

Constructors and Destructors

QScopedValueRollback()

template<typename T>

QScopedValueRollback< T >::QScopedValueRollback ( T &  var )

inline

Stores the previous value of var internally, for revert on destruction.

Definition at line 55 of file qscopedvaluerollback.h.

                                 :
        varRef(var)
    {
        oldValue = varRef;
    }

~QScopedValueRollback()

template<typename T>

QScopedValueRollback< T >::~QScopedValueRollback ( )

inline

Assigns the previous value to the managed variable.

This is the value at construction time, or at the last call to commit()

Definition at line 61 of file qscopedvaluerollback.h.

    {
        varRef = oldValue;
    }

Functions

commit()

template<typename T>

void QScopedValueRollback< T >::commit ( )

inline

Updates the previous value of the managed variable to its current value.

Definition at line 66 of file qscopedvaluerollback.h.

    {
        oldValue = varRef;
    }

Properties

oldValue

template<typename T>

T QScopedValueRollback< T >::oldValue

private

Definition at line 73 of file qscopedvaluerollback.h.

Referenced by QScopedValueRollback< T >::commit(), QScopedValueRollback< T >::QScopedValueRollback(), and QScopedValueRollback< T >::~QScopedValueRollback().

varRef

template<typename T>

T& QScopedValueRollback< T >::varRef

private

Definition at line 72 of file qscopedvaluerollback.h.

Referenced by QScopedValueRollback< T >::commit(), QScopedValueRollback< T >::QScopedValueRollback(), and QScopedValueRollback< T >::~QScopedValueRollback().

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

• /src/corelib/tools/qscopedvaluerollback.h
• /src/corelib/tools/qscopedvaluerollback.cpp