- Assigning a Procedure variable
- Multiple assignment of a Procedure variable
- Runtime order of procedures
- Passing Procedure parameters by reference or by value
- Call to the procedures found in a Procedure variable
Procedure (Type of variable) In french: Procedure
The Procedure type is used to handle: - the procedures or methods found in the project.
- the procedures or methods in an internal component.
- the procedures or methods in an external component.
This type of variable is very useful, especially: - to optimize the time for starting the procedures. Using this type of variable allows you to replace the procedures run by ExecuteProcess.
- to implement advanced algorithms (custom events, notifications, ...).
This help page presents:
p is procédure
// Assign the Procedure variable with the "MyProcedure" procedure found in the project
p = MyProcedure
// Run the procedure
p(5)
// Equivalent to MyProcedure(5)
Remarks Assigning a Procedure variable A Procedure variable can be assigned with: - a procedure known in the project.
The following syntax must be used:
<Name of Procedure variable> = <Procedure>
For example:
p is procédure
p = CheckExistence
Remarks: - The <Procedure> parameter must correspond to a procedure found in the project.
- The <Procedure> parameter must not be enclosed in quotes.
- The <Procedure> parameter must not be followed by call parameters.
- The <Procedure> parameter must not correspond to the name of an internal procedure.
   a procedure dynamically compiled by Compile.
The following syntax must be used:
<Name of Procedure variable> = Compile(<Procedure code>) or <Name of Procedure variable> = Compile(<Procedure Name>, <Procedure Code>)
For example:
p is procédure
p = Compile("RESULT n1 + n2")
Remarks: - If the name of the procedure is specified, the procedure can also be executed by Execute and ExecuteProcess.
- By default, the procedure dynamically compiled is a global procedure. To define a local procedure, you muse use the syntax defining the name of the procedure in order to specify the requested element in the name of the procedure.
- a class method.
The following syntax must be used:
<Name of Procedure variable> = <Method>
Remarks: - The <Method> parameter can correspond to a method of the current class or of a base class.
- If <Method> is an instance method, the following notation should be used:
Other possible syntaxes - You also have the ability to copy the procedures of a Procedure variable into another Procedure variable. The syntax is as follows:
<Name of destination Procedure variable> =
<Name of Source Procedure Variable>
Remark: It is a copy of variable: any modification made to one of the variables will not be applied to the other one. - You also have the ability to find at runtime a procedure identified by its name and to assign it to a Procedure variable. In this case, the following syntax must be used:
<Name of Procedure variable> = <Procedure name (with quotes)>
Remark: Using this syntax to assign a Procedure variable takes quite a long time because the name of the procedure is sought in all the procedures of the project. - Assignment by reference (<- operator)
The assignment by taking reference forces the destination element to reference the same data area as the source element.
Therefore, a Procedure variable can be handled by another Procedure variable. To do so, we must retrieve a reference on the Procedure variable itself. Any future modification made to one of the variables will be applied to the other one.
The following syntax must be used:
<Name of destination Procedure variable> <- <Name of source Procedure variable>
Multiple assignment of a Procedure variable Several procedures or methods can be assigned to a Procedure variable via the "+=" operator. The different procedures will be called one after another. For example:
p is procédure
p += Proc1
p += Proc2
Remark: To delete a procedure from a Procedure variable, you have the ability to use the "-=" operator. For example:
p is procédure
p += Proc1
p += Proc2
...
p -= Proc2
Runtime order of procedures You have the ability to replace or insert a procedure before or after the other procedures in a Procedure element via Before and After. Example:
p is procédure
p = MyProcedure
p.After = MyProcedureCalledAfter
p.Before = MyProcedureCalledBefore
// The order for calling the procedures will be:
// - MyProcedureCalledBefore
// - MyProcedure
// - MyProcedureCalledAfter
p()
Passing Procedure parameters by reference or by value To handle a procedure as parameter of another procedure, you must use a typed parameter. The following syntax must be used: - to pass parameters by reference:
PROCEDURE <ProcedureName>(MyProcedure is Procedure)
- to pass parameters by value:
PROCEDURE <ProcedureName>(LOCAL MyProcedure is Procedure)
The possible calls to the <ProcedureName> procedure are: - call while specifying a procedure known by the project: the following syntax must be used:
ProcedureName(<Project procedure>)
Remarks: - The <Project Procedure> parameter must correspond to a procedure found in the project.
- The <Project Procedure> parameter must not be enclosed in quotes.
- The <Project Procedure> parameter must not be followed by shortcuts.
- call while specifying a class method: the following syntax must be used:
Remarks: - The <Method> parameter can correspond to a method of the current class or of a base class.
- If <Method> is an instance method, the following notation should be used: <An_Object>.<Method>.
- call with reference to a procedure variable: the following syntax must be used:
ProcedureName(<Name of Procedure variable>)
- call with search at runtime for a procedure identified by its name: the following syntax must be used:
ProcedureName(<Procedure name (with quotes)>)
Call to the procedures found in a Procedure variable The call to the procedures found in a Procedure variable is performed by the standard syntax of procedures. This syntax is directly used on the Procedure variable with brackets containing 0, 1 or several parameters:
<Name of Procedure variable> ([<Parameter 1> [, ...[, <Parameter N>]]])
Examples:
p1 is procédure
p1 = Proc1
p1()
p2 is procédure
p2 = Proc2
p2(1,2)
If the Procedure variable contains several procedures, all the procedures are run according to the order of assignments.
p3 is procédure
p3 += Proc3_1
p3 += Proc3_2
p3("parameter") // calls Proc3_1 and Proc3_2
Managing the return value - If the Procedure variable contains a single procedure, the call returns the return value of the procedure.
- If the Procedure variable contains several procedures, the call returns the return value of the last procedure called.
Related Examples:
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Unit examples (WINDEV): The Procedure type
[ + ] Using the Procedure type of WLanguage. This Procedure type is used to easily manage a list of procedures. You have the ability to dynamically add some or delete some (with the += and -= operators)
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