VariableGuard< T > Class Template Reference

Resets a variable when the object goes out of scope. More...

#include <VariableGuard.h>

Inheritance diagram for VariableGuard< T >:

Public Member Functions
	VariableGuard (T &variable)
	Guards the given variable, restoring its value when this object instance goes out of scope. More...
	VariableGuard (T &variable, T value)
	Guards the given variable, and sets it to the specified value. More...
	~VariableGuard ()
	Restores the variable to its original value. More...
T	GetCurrentValue () const
	Retrieves the current value of the guarded variable. More...
void	SetCurrentValue (T value)
	Sets the variable to the specified value. More...
void	RestoreValue ()
	Restores the variable to its original value Note that the variable will be restored again to its original value when the object instance goes out of scope. More...

Detailed Description

template<typename T>
class MaxSDK::VariableGuard< T >

Resets a variable when the object goes out of scope.

Following the principle of resource acquisition is allocation, this class, which should always be allocated on the stack, will set a variable to the given value, then set the variable back to its original value when it goes out of score. This is safer than setting things by hand since the destructor will still be executed if an exception is thrown from the guarded block. An example given a member variable mRecursionLocked:

void SomeClass::SomeFunction() {
  if (!mRecursionLocked) {
    VariableGuard<bool> guard(mRecursionLocked, true);
    // some possibly recursive code...
  }
} 

Constructor & Destructor Documentation

VariableGuard() [1/2]

VariableGuard ( T &  variable )

inline

Guards the given variable, restoring its value when this object instance goes out of scope.

Parameters

variable

- the variable to be guarded (whose value needs to be restored)

                                   :
                    mVariable(variable),
                    mOriginalValue(variable)
                { }

VariableGuard() [2/2]

VariableGuard ( T &  variable, T  value  )

inline

Guards the given variable, and sets it to the specified value.

The variable is restored to its original value when this object instance goes out of scope.

Parameters

variable	- the variable to be guarded (whose value needs to be restored)
value	- the new value the variable should be set to right away

                                                    :
                    mVariable(variable),
                    mOriginalValue(variable)
                {
                    SetCurrentValue(value);
                }

~VariableGuard()

~VariableGuard ( )

inline

Restores the variable to its original value.

                {
                    RestoreValue();
                }

Member Function Documentation

GetCurrentValue()

T GetCurrentValue ( ) const

inline

Retrieves the current value of the guarded variable.

                {
                    return mVariable;
                }

SetCurrentValue()

void SetCurrentValue ( T  value )

inline

Sets the variable to the specified value.

Upon this guard's destruction, the variable will be reset to the original value found during the guard's construction.

Parameters

value

- the new value the variable should be set to

                {
                    mVariable = value;
                }

RestoreValue()

void RestoreValue ( )

inline

Restores the variable to its original value Note that the variable will be restored again to its original value when the object instance goes out of scope.

                {
                    mVariable = mOriginalValue;
                }