Call of method in ST

Syntax
( * internal call of method of the current function block *)
THIS.method-name();|method-name();
THIS.method-name|method-name
(input_1:=x1,input_2:=x2,...,input_n:=xn,
output_1=>y1,output_2=>y2,...,output_n=>yn);
( * internal call of a method of the base function block from within a derived function block *)
SUPER.method-name();
SUPER.method-name
(input_1:=x1,input_2:=x2,...,input_n:=xn,
output_1=>y1,output_2=>y2,...,output_n=>yn)
( * external call of a method *)
instance-name.method-name();
instance-name.method-name
(input_1:=x1,input_2:=x2,...,input_n:=xn,
output_1=>y1,output_2=>y2,...,output_n=>yn);

Meaning

formal call of the →method without or with a parameter list
The method is called by the name of the method method-name. The specification in front of this name determines in which context the method is called:

  • THIS. – This calls a method of the same language construct. As an alternative, it is also possible to omit THIS. here.
    Example: THIS.UP5(); or UP5(); – This calls the method UP5 e.g. within the method UP. Both methods are declared in the same →function block or in the base function block (if the function block containing the call of the method is a derived function block; see details on the keyword EXTENDS under " Declaration of a function block in ST ").

  • SUPER. – This calls a method of the base function block from within a derived function block.
    Example: SUPER.UP5(); – This calls the method UP5 of the base function block. The method is called within a function block that has been derived from a base function block by using the keyword EXTENDS .

  • instance-name. – This calls a method of an →instance.
    Example: Inst1.UP5(); – This calls the method UP5 of the instance Inst1.

No check of recursions

Recursions for →functions and →methods are not forbidden or checked by logi.CAD 3 . Nevertheless, do not call a function/method from within itself and avoid 2 (or more) functions/methods calling each other (= mutual recursion) within your application.
Mind that recursions of functions/methods might cause unexpected results when your application is executed. For example, the application might be executed in an infinite loop and/or the →runtime system might not respond anymore.

images/s/b2ic8e/9012/1ca6q62/_/images/icons/emoticons/information.svg The possibilities for the parameter list are analogous to the call of a function .

This parameter list of a formal →call may contain the following elements:

  • →assignments to →input variables (incl. to input EN)
    The expression on the right side of the assignment operator ":=" in the assignments to input variables may be one of the constructs as listed under Assignment.

  • assignments to →in-out variables
    The expression on the right side of the assignment operator ":=" in the assignments to in-out variables may be just a construct which might be on the left side of the assignment operator ":=" as well.

  • assignments of →output variables (incl. to output ENO)
    The expression on the right side of the assignment operator "=>" in the assignments of output variables may be a declared →variable (e.g. result) of a fitting →data type.

As alternatives, you can use the following variants for the call:

  • non-formal call
    The parameter list must contain the same number of input variables, in exactly the same order and of fitting data types as given in the declaration , except the execution control parameters EN and ENO.
    Example: Inst1.UP3 (10,20,T#3ms); – This non-formal call is equivalent to the formal call: Inst1.UP3 (EN := TRUE, IN1:=10, IN2 := 20, T1 := T#3ms, OUT => result);

  • incomplete parameter list of formal call
    You can omit input variables and output variables within the parameter list. Omitted input variables get the default →initial value.     As previously mentioned, this is analogous to the call of a function (s ee the examples there.

The FAQ article "When to use a formal call? When to use a non-formal call?" lists a table when to use formal call vs. non-formal call.

An example for an internal call of a method with a parameter list but without EN / ENO is listed under " Declaration of a method ".
 An example for the different calls of methods (using THIS., SUPER. and instance-name.) is listed under "Declaration of a function block in ST".