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(autoconf.info)Macro Names

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Macro Names
===========

   All of the Autoconf macros have all-uppercase names starting with
`AC_' to prevent them from accidentally conflicting with other text.
All shell variables that they use for internal purposes have
mostly-lowercase names starting with `ac_'.  To ensure that your macros
don't conflict with present or future Autoconf macros, you should
prefix your own macro names and any shell variables they use with some
other sequence.  Possibilities include your initials, or an abbreviation
for the name of your organization or software package.

   Most of the Autoconf macros' names follow a structured naming
convention that indicates the kind of feature check by the name.  The
macro names consist of several words, separated by underscores, going
from most general to most specific.  The names of their cache variables
use the same convention (Note: Cache Variable Names, for more
information on them).

   The first word of the name after `AC_' usually tells the category of
feature being tested.  Here are the categories used in Autoconf for
specific test macros, the kind of macro that you are more likely to
write.  They are also used for cache variables, in all-lowercase.  Use
them where applicable; where they're not, invent your own categories.

`C'
     C language builtin features.

`DECL'
     Declarations of C variables in header files.

`FUNC'
     Functions in libraries.

`GROUP'
     UNIX group owners of files.

`HEADER'
     Header files.

`LIB'
     C libraries.

`PATH'
     The full path names to files, including programs.

`PROG'
     The base names of programs.

`MEMBER'
     Members of aggregates.

`SYS'
     Operating system features.

`TYPE'
     C builtin or declared types.

`VAR'
     C variables in libraries.

   After the category comes the name of the particular feature being
tested.  Any further words in the macro name indicate particular aspects
of the feature.  For example, `AC_FUNC_UTIME_NULL' checks the behavior
of the `utime' function when called with a `NULL' pointer.

   An internal macro should have a name that starts with an underscore;
Autoconf internals should therefore start with `_AC_'.  Additionally, a
macro that is an internal subroutine of another macro should have a
name that starts with an underscore and the name of that other macro,
followed by one or more words saying what the internal macro does.  For
example, `AC_PATH_X' has internal macros `_AC_PATH_X_XMKMF' and
`_AC_PATH_X_DIRECT'.