Thread (Variable type)

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Help / WLanguage / WLanguage functions / Standard functions / Process functions / Threads, semaphores, signals and mutex

Declaration
Properties specific to Thread variables
WLanguage functions that use Thread variables

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Thread (Variable type)

In french: Thread

The Thread type allows you to define all the characteristics of a thread. You can define and change the characteristics of this thread using different WLanguage properties.

Note: For more details on the declaration of this type of variable and the use of WLanguage properties, see Declaring a variable.

New in version 2025

This type of variable is now available for Android applications.

This type of variable is now available in Android widget mode.

This type of variable is now available for Java applications.

Example

// Declare a variable to handle a thread
t is Thread
// Build a thread and trigger its execution on a procedure
t = ThreadExecute(Proc, ("First parameter", 2))

// Build a thread
t is Thread(Proc, ("First parameter", 2))
// Trigger the execution of the thread
ThreadExecute(t)

Declaration

Declaring a non-described thread Hide the details

MyVariable is Thread

In this case, the thread is not described. The variable will have to be assigned with an existing thread or with the result of one of the thread execution functions.

Describing a thread via the Thread type Hide the details

MyVariable is Thread (<Procedure> [, <Parameters> [, <Options>]])

<Procedure>: Character string or Procedure variable

Procedure to run. This parameter can correspond to:
the name of the procedure to run.
the name of Procedure variable corresponding to the procedure to run.

<Parameters>: List of values enclosed in brackets and separated by commas

Parameters of procedure to run. This list of parameters has the following format:
(<Parameter 1>, ..., <Parameter N>)
where:
<Paramètre 1> First parameter of the procedure.
...
<Paramètre N> Nth parameter of the procedure.

<Options>: Optional Integer constant

Mode for starting the thread.
threadFullCopyHFSQLContext
(Default value) Triggers the immediate copy of the current HFSQL context.
Recommended if the thread must take into account the current positions in the files and queries of caller context.
threadGlobalContext Forces the use of the global context of the project if the thread is run from a window. The thread will continue to run until the application is closed.
The window context is used by default, therefore the thread is stopped when closing the window.
threadLightCopyHFSQLContext Triggers the immediate copy of a part of the current HFSQL context.
The following are memorized:
the directories where the HFSQL Classic data files are located.
HFSQL Client/Server connections.
threadWaitForStart Waits for the actual start of the thread before continuing the execution.

In this case:

the thread is described and its description can no longer be modified.
The thread is not executed automatically, so a declaration alone will not start the execution of the thread. You must call one of the thread execution functions to start the thread execution.
thread is automatically secured. In this mode:
- a compilation error will be displayed if fields are accessed in the thread.
- an exception will be thrown:
  - if the thread accesses the controls at runtime,
  - if the ThreadStop function is called.
- when the window that triggered the thread is closed, a request to stop the thread is generated (but the thread continues to run after the window is closed).

Properties

Properties specific to Thread variables

The following properties can be used to handle Thread variables:

Property name	Type used	Effect

New in version 2025 Extra	Variant	Allows you to store advanced information without affecting the execution of the application. You can store values of any type (array, etc.). It is also possible to add members to the Extra property. Example: MyVariable.Extra.Info1 = Value MyVariable.Extra[Info2] = Value2 MyVariable.Extra.Date = DateSys()
Name	Character string	Thread name. This property is read-only.
Priority	Integer constant	Current priority level of thread: High priority: High priority. Normal priority: Normal priority. Low Priority: Low Priority. Not available.
ReturnedValue	Value returned by the thread.	Caution: If the thread is still running, the ReturnedValue property blocks the execution until the thread terminates. If the thread terminates without a fatal error, the property returns the return value(s) of the main procedure of the thread. This property is read-only. Reminder: The State property is used to determine the state of the thread. It is possible to wait for the end of a thread with ThreadWait. New in version 2025 This property is non-blocking under Android 6. An error appears if the thread has not been completed.
Status	Integer constant	Thread status: threadStopRequested: Thread stop requested. threadEncours: The thread is currently running.. threadNotExecuted: Thread not executed. threadSuspended: The thread is suspended. threadTerminated: The thread exists but is terminated.. This property is read-only.
StopRequested	Boolean	True if the thread was requested to stop, False otherwise. This property is read-only.

Remarks

WLanguage functions that use Thread variables


ThreadExecute	Starts the execution of a secondary thread.
ThreadRequestStop	Sends a stop request to a thread.
ThreadSendSignal	The current thread sends a signal to the specified thread in order to unlock it.
ThreadWait	Waits for the end of the execution of the specified thread.