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).
