Control (Type of variable)

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Declaring a Control variable
Assigning a Control variable
Using a Control variable in a procedure
Optimizing the processes with indirection
Properties associated with a Control variable
Functions that handle a Control variable

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Control (Type of variable)

In french: Champ

The Control type is used to define the characteristics of a control. This control can be dynamically created by ControlCreate or it can be a control found in a window or in a report.

ControlCreate is not available.

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

Example

// Dynamically create a control in a window
c is Control
c <- ControlCreate("BUTTON_1", typBouton, 30, 40, 140, 20) // Caution, not '='

c.Caption = "Click here"

c.Process[trtClick] = myProcedure

Remarks

Declaring a Control variable

The following syntax is used to declare a Control variable:

<Variable Name> is Control

Assigning a Control variable

A Control variable can be used to handle:

a control found in a window or in a report.
a control created by ControlCreate.

The assignment of a Control variable must be performed by the '<-' operator.

Examples:

// Assignment with an existing control
c is Control
c <- EDT_Edit1

// Assignment by using the indirection
// The variable references the EDT_EDIT2 control
c <- {"EDT_EDIT2"}

// Assignment with a control created by ControlCreate
c is Control
c <- ControlCreate("BUTTON_1", typButton, 30, 40, 140, 20)

Caution: The '=' operator must not be used to assign a Control variable. This operator is used to transfer the value of a control into another control of the same type. For example:

// Assignment with an existing control
c is Control
c <- EDT_Edit1

// Modify the value
c = EDT_Edit3 // Equivalent code: EDT_Edit1.Value = EDT_Edit3.Value

c = "Text" // Equivalent code: EDT_Edit1.Value = "Text"

Remark: To know if a value has been assigned to the Control variable, use the Type property on the variable.

Using a Control variable in a procedure

The Control type can be a parameter of a procedure. You can write for example:

the code of the procedure:
PROCEDURE MyProcedure(C is Control)
C = "It is " + TimeSys()
the call to the procedure:
MyProcedure(EDT_Edit1)

Optimizing the processes with indirection

The Control type can be used to optimize the processes that use the indirections. You can write for example:

C is Control <-{s, indControl}
C.Width = 10
C.Height = 20

rather than the following code:

{s, indControl}..Width = 10
{s, indControl}..Height = 20

Properties associated with a Control variable

The Control type is used to handle all types of controls found in a window or in a report. The available properties depend on the type of control used.

Therefore, if a Control variable is used to handle an edit control, all the WLanguage properties available for the edit control will be usable on the Control variable.

To get the properties of a control, see the control help page: the "See Also" link is used to access all the control properties. For more details, see Window controls.

Functions that handle a Control variable

All the WLanguage functions that handle the controls can be used on a Control variable. However, only the WLanguage functions corresponding to the type of control used will be available.

Therefore, the TableXXX functions can be used on a Control variable that handles a Table control.