7.1 Global m4 Settings

The ``settings'' set of m4 commands defines the m4 environment that is used in the CÆSAR Code Package:

• The m4 quotation characters are changed to ``['' and ``]'', to avoid interaction with standard F90 syntax.
• The m4 comment character is changed to ``!'', to coincide with the F90 comment character. Note that comments in m4 are echoed to the output with no macro expansion. To avoid echoing at all, the m4 command ``dnl'' must be used (this may change in future versions of Gnu m4).
• Builtin m4 macros must be called with a prefix of ``m4_''. For example, the ``format'' macro must be called via ``m4_format''. Therefore, all of the m4 preprocessing in the CÆSAR Code Package must be done with Gnu m4, using either the -P or -prefix-builtins option.
• Certain commonly used m4 builtins are defined to be usable without an ``m4_'' prefix.

In addition to these environmental settings, some globally useful macros are defined.

m4 macros defined in the include/settings.m4 file:

	__date__		Date field (mm/dd/yy).
	__file__		Unprefixed form of m4___file__.
	__line__		Unprefixed form of m4___line__.
	__time__		Time field (hh:mm:ss, 24-hour).
	define		Unprefixed form of m4_define.
	dnl		Unprefixed form of m4_dnl.
	expand		Force macro expansion in words containing underscores.
	firstword		Returns the first word from a space-delimited list of words.
	forloop		A numerical text iterator (see code listing for input/output details).
	fortext		A textual text iterator (see code listing for input/output details).
	ifdef		Unprefixed form of m4_ifdef.
	ifelse		Unprefixed form of m4_ifelse.
	include		Unprefixed form of m4_include.
	m4_chop		Removes last character of input string.
	m4_die		Prints error message and terminates.
	popdef		Unprefixed form of m4_popdef.
	pushdef		Unprefixed form of m4_pushdef.
	tailwords		Returns everything except the first word from a space-delimited list of words.
	undefine		Unprefixed form of m4_undefine.

The Settings m4 Macros code listing contains additional documentation.