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.TH MI5 1df "June 2017" "Manual page for mi5"
.SH NAME
.B mi5
\- m4 inverted preprocessor
.SH SYNOPSIS
.B mi5
FILE > out.m4
.br
.B mi5
FILE1 FILE2 > out.m4
.br
prog |
.B mi5 > out.m4
.br
.SH DESCRIPTION
.B mi5
is a simple and crude m4 preprocessor to make using m4 slightly more bearable
and predictable for its author, who wants badly to like m4 but doesn't. It's
primarily intended for situations where the majority of a file is simple static
text, and only a few simple macros need to be defined and expanded, which
covers almost every usage case for the author. It's written to work with any
POSIX m4.
.P
mi5 inverts m4's usual approach by approaching most of the file as if it were
part of an m4 comment, with <% and %> as the delimiters to specify markers in
which macro expansion should occur. This makes m4 work in a way reminiscent of
templating libraries or languages like PHP.
.P
Macros can be expanded as blocks:
.P
<%
define(`FOO', `bar')
define(`BAZ', include(`include/quux.inc')
?>
.P
For this format, "dnl" macros to delete newlines for each declaration are
inserted for you. Blank lines are skipped, and leading and trailing spaces are
ignored. The above code therefore produces no actual output, as it only has two
define calls.
.P
For inline expansion, the syntax is similar, but the behaviour slightly different:
.P
The value of the FOO macro is <% FOO %>.
.P
Spaces immediately after the opening delimiter and before the closing delimiter
are ignored, but spaces produced within the macro are preserved.
.P
Ideally, you do macro definition in an mi5 block at the top of your file, and
very simple macro expansion in an mi5 inline.
.SH CAVEATS
Only very simple macro expansions work in inline calls at the moment. This can
be fixed by the author tokenizing the line properly, which he'll do Real Soon
Now (TM). Specifically, neither comment delimiters nor macro parameters work.
The latter is because of a nasty corner-case in m4 where parameter expansions
$1, $2, $*, etc are expanded
.B even within comments,
one of m4's darkest corners. The workaround is to do as much logic as you can
in a block, defining your result as a single simple macros, and then expanding
that inline.
.SH SEE ALSO
bp(1df), xargs(1)
.SH AUTHOR
Tom Ryder <tom@sanctum.geek.nz>
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