QScopeGuard Class

Provides a scope guard for calling a function at the end of a scope. More...

Header: #include <QScopeGuard>
qmake: QT += core
Since: Qt 5.12

This class was introduced in Qt 5.12.

Public Functions

void dismiss()
QScopeGuard<F> qScopeGuard(F f)

Detailed Description

Member Function Documentation

void QScopeGuard::dismiss()

Disarms the scope guard, so that the function F will not be called at the end of the scope.

Related Non-Members

QScopeGuard<F> QScopeGuard::qScopeGuard(F f)

The qScopeGuard function can be used to call a function at the end of the scope.

QScopeGuard<F> is a class which sole purpose is to run a function F in its destructor. This is useful for guaranteeing your cleanup code is executed, whether the function is exited normally, exited early by a return statement, or exited by an exception.

If F is a lambda then you cannot instantiate the template directly, therefore the qScopeGuard() helper is provided and QScopeGuard<F> is made a private implementation detail.

Example usage is as follows:


  void myComplexCodeWithMultipleReturnPoints(int v)
  {
      // The lambda will be executed right before your function returns
      auto cleanup = qScopeGuard([] { code you want executed goes HERE; });

      if (v == -1)
          return;

      int v2 = code_that_might_throw_exceptions();

      if (v2 == -1)
          return;

      (...)
  }

Note: Exceptions are not supported. The callable shouldn't throw when executed, copied or moved.

See also QScopedValueRollback.