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5
The Elements of PlanetPress Talk
PlanetPress Talk includes all of the features one expects in a scripting language. It has a defined set of data
types (see “Data Types” on page 8) and the following categories of elements that you use to build scripts:
What are the elements of the PlanetPress Talk scripting language?
Category: Description:
Variables A variable is a value that changes over time. See “Variables” on page 13.
System objects An object is a set of related system variables. For example the
physical system object
contains the system variables that describe the current x and y coordinates of the drawing
pen on the physical page. You reference one of the system variables in an object by prefixing
the name of the system object to the name of the variable. For example
&physical.x
references the x coordinate system variable in the physical system object.
Operators and
Operator functions
An operator is a symbol that performs a common operation. For example, the
+ is an
operator that adds two numbers together or concatenates two strings. An operator function
is an operator that does not use a symbol to represent its operation. For example the
add
command is an operator function. Both operators and operator functions operate on one or
more operands. For example the
add command operates on two measure or integer values
(the operands). See “Operators and Operator Functions” on page 44 for a complete list of all
operators and operator functions available in PlanetPress Talk.
Procedures A procedure performs an action. For example the
curveto procedure draws a Bezier curve,
the
rectangle procedure draws a rectangle, and the setfillcolor procedure sets the fill
color. Most procedures require arguments. For example, the
rectangle procedure requires
six arguments: the x and y coordinates of the upper left hand corner of the rectangle, the
width and height of the rectangle, and whether it is filled and/or stroked.
Functions A function performs an action and returns a value. For example the
inttostr function
converts an integer to a string, and returns the value of the resulting string. A function thus
has a data type that corresponds to that of the value it returns. You assign the result of a
function to a variable or use it as an argument in another command. Most functions require
arguments. For example the
inttostr command requires a single argument: the integer you
want to convert to a string; it returns a string and thus the
inttostr function is of type string.
Loop structures Repeat a sequence of one or more commands until a specified condition is met. See “Loop
Structures” on page 48.
Condition structures Control when a sequence of one or more commands executes. See “Condition Structures” on
page 48.
Comments Provide a means for embedding documentation in your code, or for commenting out lines
of code during debugging. See “% (procedure)” on page 62.