AmigaOS Manual: ARexx Glossary

This glossary provides definitions of terms used in the ARexx manual.

Address

An identifying number assigned to every byte of information in a computer's memory and every sector on a disk.

argument

An additional piece of information included with an instruction or function. The argument determines the action to be taken.

assignment clause

A variable symbol (simple, stem or compound symbol) followed by an = operator. In an assignment clause, the token to the right of the = sign are evaluated and the result is assigned to the variable symbol.

Boolean

Having two possible states: 0 (false) or 1 (true).

clause

The smallest executable language unit.

clip list

A clipboard used for intertask communication. Names and value pairs can be added to the clip list with the SETCLIP() function.

command clause

An ARexx expression in which the result is issued as a command to an external application.

command interface

A message port through which ARexx issues commands to compatible applications.

comment

A group of characters enclosed in /*...*/ symbols. Each ARexx program starts with a comment.

compound symbol

A token made up of alphanumeric or ., !, ?, $, _ characters with one or more periods within the name. Compound symbols have the structure stem.n1.n2...nk.

concatenation

The process of linking together two strings.

debugging

Finding and fixing errors in a program.

delimiter

A character that marks the beginning and end of a string. ARexx delimiters are a single quote (') and a double quote (").

expression

A group of tokens to be evaluated. Expressions are made up of strings, symbols, operators, and parentheses.

fixed symbol

A token beginning with a digit or a period.

function

A group of statements that can be executed as a whole. Functions allow you to build complex programs from smaller modules.

function hosts

An external application that contains an ARexx port. The name of a function host is the name of the program's public message port.

function libraries

A collection of one or more functions organized as an Amiga shared library. A function library must contain a library name, a search priority, an entry point offset, and a version number.

global environment

The fixed components of an ARexx program, including the program source code, static data strings, and argument strings.

host address

In an outside application, the host address is the name of the message port to which ARexx commands can be sent.

instruction

A clause beginning with a certain keyword that tells ARexx to perform an action.

interprocess communication

The exchange of information between applications.

interrupts

Internal flags in ARexx that allow a program to detect errors and retain control when the program would normally abort. Interrupts are controlled by the SIGNAL: instruction.

iteration

Repeating a section of a program.

label

A symbol token followed by a colon (:). Labels identify a particular location in the program.

library list

An internal list, maintained by ARexx, of all the currently available function libraries and function hosts. Applications can add or remove function as needed.

macro

Another name for an ARexx program.

marker

A token that determines the beginning and end of a parse string.

message port

An interface in an Amiga application that allows the program to communicate with an ARexx program.

null clause

A blank line or a comment line.

numeric precision

The number of decimal places in an arithmetic result. As the number of decimal places decreases, the result becomes less precise.

operators

A character such as (+), (-), or (|) used in an arithmetic, concatenation, comparison, or logical operation.

parsing

Breaking a string into smaller units.

return code

The severity level of an error. This number (5, 10, or 20) is displayed when an error occurs in an ARexx program.

RexxMast

The program that acts as an interpreter for ARexx programs.

simple symbol

A token that does not begin with a digit or contain any periods.

statement

An assignment, instruction, or command clause.

stem symbol

A token that has one period at the end of its name. Stem symbols are used to initialize compound symbols.

storage environment

The variable components of an ARexx program, including the symbol table, numeric options, trace options, and host address strings.

string

A group of characters beginning and ending with a delimiter (single or double quote). The value of a string is the string itself.

symbol

Any group of the alphanumeric characters a-z, A-Z, 0-9, period (.), exclamation point (!), question mark (?), dollar sign ($), or underscore (_).

symbol table

An internal table created by ARexx that stores the value strings that have been assigned to the variables in a program.

target

A symbol, usually a variable symbol, that is assigned a value during a parsing operation.

template

A group of tokens that specifies the variables used in a parsing operation. It also specifies the way in which the values will be determined.

tokenization

The process of breaking a statement into its individual tokens.

tokens

The smallest entities of the ARexx language.

tracing

Displaying the lines of an ARexx program as the program is executing. This allows you to determine exactly where any errors are occurring.

variable

A symbol that can be assigned a value.