• How to declare and initialize a variable,
• How to access the properties of a variable,
• The rules for variable scope.

Declaring a variable

Declaring a variable and inializing it

Declaring several variables

Detailed syntaxes

• The a and an keywords are optional: they provide better readability.
• When several variables of the same type are declared and initialized on the same line, only the last variable is initialized.
  To declare and initialize several variables at the same time, use the multiple initialization.
• Several variables with the same name cannot be used in the same process (regardless of the type of these variables).
• The "useful" attribute can be used when declaring a variable to specify that it is used in the project. This notation avoids displaying the warning indicating that a local variable is unused. In this case, the following syntax must be used:
  
  <Variable name> is <Type>, useful[ = "Reason"]
  
  <Variable name> is <Type> <useful [ = "Reason"]>
  "Reason" is a note for the developer.
  Example:
  
  n1 is int, useful = "Variable required by the Webservice"
   
  n2 is int <useful = "Variable required by the Webservice">
  

Examples

• Declaring simple variables:
  
  CustomerName is string
  Counter is int
  Price is real
  i,j,k are int
  
  
  The type inference allows you to use the following syntaxes:
  
  let Amount = 1500.69 // real type
  let City = "Montpellier" // string type
  
• Declaring a Border variable:
  
  MyBorder is Border
  

Associating a critical section with a variable

When declaring a variable, this variable can be associated with a critical section by using the critical section attribute.

The syntax is as follows:

VariableName is VariableType <critical section>

or

VariableName is VariableType, critical section

The code sections that use these variables must be found between CriticalSectionStart and CriticalSectionEnd.

Special case: A critical section is automatically associated with the variables on which simple operations are performed, such as:

• assigning a value.
• retrieving a value.
• incrementat, decrement (+, -, ++, --, +=, -= operators +, -, ++, --, += -=).

Example:

// Global declarations of WIN_STAT window
gcySum is currency, critical section
gcyMax is currency, critical section
...

// Code run by several threads
cyOrderAmount is currency
...
// atomic operation, the critical section is automatically managed by WLanguage
gcySum += cyAmountOrder
 
// multiple operation, it is necessary to implement the critical section explicitly
USING CriticalSection(gcyMax) IN
IF cyAmountOrder > gcyMax THEN
gcyMax = cyAmountOrder
END
END

Remarks:

• The critical section attribute is allowed for:
  • the global project variables, set of procedures, window, page and report.
  • the local variables.
  • the members of classes.
  • the arrays: in this case, the attribute is associated with the array and not with the array elements.
• The queues and the stacks are protected by default: the critical section attribute is not required.

Not available in Android and in Android widget.

Syntaxes

• Assigning a property of the variable:
  
  <Variable name>.<Property> = <Value>
• Reading a property of the variable:
  
  <Variable name>.<Property>

Example

Rule

• If a variable "global" to the project and a variable "global" to a window have the same name:
  • the variable "global" to the window will be used in all the events or processes of the window and window controls as well as in its "local" procedures.
  • the variable "global" to the project will be used in all the other processes.
• If a variable "global" to the project and a variable "local" to a process have the same name:
  • the "local" variable will only be used in the process where this variable was declared.
  • the variable "global" to the project will be used in all the other processes.
• If a variable "global" to a window and a variable "local" to a process of this window have the same name:
  • the "local" variable will only be used in the process where this variable was declared.
  • the variable "global" to the window will be used in all other events or processes of the window and its controls (as well as in its "local" procedures).
  • none of these two variables can be used in the rest of the project.

Exception

Special case: Reports & Queries

• The variables global to the project can be used in the reports and queries created and/or modified in "Reports & Queries".
• The items for which "Visible to the end user in "Reports and Queries"" is checked in the data model editor can be used in "Reports and Queries". If this option is not checked, the item can only be used by indirection (the autocomplete feature is not available to the user, the item is not available in the wizards, description windows, etc.).

Name conflict: ambiguous use of a type