| procedureCall | statement |
| Syntax | A procedureCall is:
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| Description | A procedure call is a statement that calls (invokes or activates) a procedure. If the procedure has parameters, a parenthesized list of expressions (expns) must follow the procedure's name (procedureId).
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| Example |
procedure greet
put "Hello"
end greet
greet % This is a call to the greet procedure
procedure times ( var i : int, factor : int)
i := factor * i
end times
var j : int
times ( j, 4 ) % Multiply j by 4
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| Details | A parameter declared in the header of a procedure is a formal parameter. For example, i and factor above are formal parameters. Each expression in the call is an actual parameter. For example, j and 4 above are actual parameters. If a formal parameter is declared using var, then the expression passed to that parameter must be a variable reference (so its value can potentially be changed by the procedure). This means, for example, that it would be illegal to pass j+3 as the first parameter to times. The variable reference and the formal parameter must have equivalent types (see equivalence for details). Each actual parameter passed to a non-var formal parameter must be assignable to that parameter (see assignability for details). See also procedureDeclaration. In this explanation of procedureCall, we have up to this point ignored the possibility of procedures exported from modules, monitors and classes. If the procedure is being called from outside of a module or monitor M from which it has been exported, the syntax of the procedureCall is:
M . procedureId [ ( [ expn {, expn } ] ) ]
In other words, the module or monitor name and a dot must precede the procedure's name. If the procedure is being called from outside of a class from which it has been exported, the syntax of the procedureCall is one of:
(a) classId (p) . procedureId [ ( [ expn {, expn } ] ) ]
(b) p -> procedureId [ ( [ expn {, expn } ] ) ]
In these, p must the a pointer value that locates an object in the class. Form (b) is a short form for form (a).
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| See also | class.
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