Macro
A name (possibly followed by a
formal argument list) that is equated to a text or symbolic expression to which it is to be expanded (possibly with the substitution of actual arguments) by a macro expander.
The term "macro" originated in early
assemblers, which encouraged the use of macros as a structuring and information-hiding device.
During the early 1970s, macro assemblers became ubiquitous, and sometimes quite as powerful and expensive as
HLLs, only to fall from favour as improving
compiler technology marginalised
assembly language programming (see
languages of choice).
Nowadays the term is most often used in connection with the
C preprocessor,
Lisp, or one of several special-purpose languages built around a macro-expansion facility (such as
TeX or
Unix's
troff suite).
Indeed, the meaning has drifted enough that the collective "macros" is now sometimes used for code in any special-purpose application control language (whether or not the language is actually translated by text expansion), and for macro-like entities such as the "keyboard macros" supported in some text editors (and
PC TSRs or
Macintosh INIT/CDEV keyboard enhancers).
