macro

views updated May 18 2018

macro Short for macroinstruction. An instruction in a programming language (almost always but not necessarily assembly language) that is replaced by a sequence of instructions prior to assembly or compiling. A macroassembler permits the user to define macros, specifying the macroinstruction form, its arguments, and a replacement text (otherwise called the body of the macro), and then allows macroinstructions to be interspersed among the assembly code. On encountering a macro the assembler replaces it by the macro body, substituting the parameters provided in the places marked in the macro body. The macro thus provides a mechanism for inserting a particular body of text at various places in a program (and is thus the same thing as an open subroutine, though this nomenclature is obsolete).

A macroprocessor provides similar facilities, though not in combination with an assembler. It accepts macro definitions and then reads arbitrary text in which macro calls (i.e. instances of a macro name) can occur. Text is copied to the output until a macro name is encountered: when this happens the arguments (parameters) are found and the macro call is replaced by the macro body in the output stream, with appropriate substitution of the parameters.

macro

views updated May 23 2018

mac·ro / ˈmakrō/ • n. (pl. -ros) 1. (also macro instruction) Comput. a single instruction that expands automatically into a set of instructions to perform a particular task.2. Photog. short for macro lens.• adj. 1. large-scale; overall: the analysis of social events at the macro level. Often contrasted with micro.2. Photog. relating to or used in macrophotography.