.. highlightlang:: us

.. _us_lock:

us_lock
=======

.. index:: us_lock

.. us.tag us_lock NOTREADYENGLISH ProgMisc New5145

:ref:`us_lock` locks the Windows message loop
while an UniScript function is executed.

.. function:: old_lock = us_lock(bLock)

.. us.return

**Return Value**

*old_lock* is the value of the lock flag before the function call.

.. us.params

**Parameters**

.. uparam:: bLock

   If *bLock* is TRUE (1) the message loop is locked
   and if *bLock* is FALSE (0) the message loop is unlocked.

.. us.comment

**Comment**

If the lock flag is enabled, the execution of a UniScript function cannot
be aborted (via ESC key or Ctrl+C). Paint messages are not executed, the
UniPlot window is not updated. It is also not possible to start another 
UniScript command.

If the lock flag is not set to ``us_lock(FALSE)`` 5 seconds after 
``us_lock(TRUE)`` has been called it will be set to FALSE automatically.

The following while loop cannot be interrupted for 5 seconds (Ctrl+C or ESC).

::

   { us_lock(1); while (1) a=1; }

.. us.example

**Example**

::

   old = us_lock(TRUE);
   
   // Do something

   us_lock(old);

.. us.history

.. us.history

**History**

.. list-table::
   :header-rows: 1

   * - Version
     - Description
   * - 5.14.5
     - New.

.. seealso::
   :ref:`overview-programming`

:sub:`id-47519`