Basic Characteristics RAPID

Basic Characteristics RAPID Expressions
7.5 Using aggregates in expressions
An aggregate is used for record or array values.
Example: pos := [x, y, 2*x]; pos record aggregate
posarr := [[0, 0, 100], [0,0,z]]; pos array aggregate
It must be possible to determine the data type of an aggregate the context. The data type
of each aggregate member must be equal to the type of the corresponding member of
the determined type.
Example VAR pos pl;
p1 :=[1, -100, 12]; aggregate type pos - determined
by p1
IF [1, -100, 12] = [a,b,b,] THEN illegal since the data type of neither
of the aggregates can be
determined by the context.
7.6 Using function calls in expressions
A function call initiates the evaluation of a specific function and receives the value
returned by the function.
Example: Sin(angle)
The arguments of a function call are used to transfer data to (and possibly from) the
called function. The data type of an argument must be equal to the type of the corresponding
parameter of the function. Optional arguments may be omitted but the order
of the (present) arguments must be the same as the order of the formal parameters. In
addition, two or more optional arguments may be declared to exclude each other, in
which case, only one of them may be present in the argument list.
A required (compulsory) argument is separated from the preceding argument by a
comma “,”. The formal parameter name may be included or omitted.
Example: Polar(3.937, 0.785398) two required arguments
Polar(Dist:=3.937, Angle:=0.785398)... using names
An optional argument must be preceded by a backslash “\” and the formal parameter
name. A switch type argument is somewhat special; it may not include any argument
expression. Instead, such an argument can only be either "present" or "not present".
Example: Cosine(45) one required argument
Cosine(0.785398\Rad) ... and one switch
Dist(p2) one required argument
Dist(\distance:=pos1, p2) ... and one optional
Conditional arguments are used to support smooth propagation of optional arguments
through chains of routine calls. A conditional argument is considered to be “present”
if the specified optional parameter (of the calling function) is present, otherwise it is
RAPID Reference Manual 5-29