Local Variables And Parameter Keywords - AMX AXCESS CONTROL SYSTEM PROGRAM Instruction Manual

Local Variables and Parameter Keywords

The Local Variables and Parameter keywords supported by Axcess are described below:
Local Variables and Parameter Keywords
CALL
To tell Axcess to execute a
subroutine, use the CALL
keyword and the name of the
subroutine in single quotes.
DEFINE_CALL
In Axcess, subroutines are
created using the
DEFINE_CALL statement.
LOCAL_VAR
This keyword is used inside a
DEFINE_CALL to declare
local variables.
Axcess Programming Language
For example, to execute the subroutine LIGHTS OFF, type the following where
you want the CALL to occur:
CALL 'LIGHTS OFF'
When Axcess executes the CALL, program execution jumps to the first line
inside the braces of the DEFINE_CALL. The subroutine is executed only once,
and then Axcess returns to the statement directly following the CALL state-
ment.
The subroutine name follows the DEFINE_CALL keyword, enclosed in single
quotes. There are certain restrictions for these subroutine names:
• They cannot be previously defined constants or variables.
• They cannot be names that have already been assigned to BUFFERS or
WAITs.
• They are case-sensitive. For example, Test and TEST are not the same.
Subroutines must be defined before they can be used. For this reason,
DEFINE_CALLS are typically placed right before the DEFINE_START section
of the program. Here is the format:
DEFINE_CALL 'subroutine name'
{
(* The subroutine goes here *)
}
Spaces in the subroutine name are allowed because it is a string literal. Notice
that the subroutine's code is enclosed in braces. No matter how long the sub-
routine is, it must be in this format.
A local variable is a variable which is declared inside a DEFINE_CALL and can
only be used inside that same DEFINE_CALL. Variables declared in the main
DEFINE_VARIABLE section are called global variables. The words local and
global refer to a variable's scope, which determines the parts of the program
that can access the variable. Global variables have global scope; that is, the
entire program has access to them. A local variable has local scope, and can
only be accessed inside the DEFINE_CALL in which it is declared.
A local variable can have the same name as a local variable in another subrou-
tine. A local variable can also have the same name as a global variable. If this
happens, the local variable takes precedence in its scope; the global variable is
hidden.
Local variables are best used in cases where a subroutine needs to use a vari-
able, but no other piece of code needs it. Such variables are usually temporary
flags, loop counters, and other variables a subroutine may need to do its work.
Local variables are also static, meaning that they retain their values between
calls to the subroutine.
Using Subroutines
93