There is a special notation for the number of actual arguments supplied, and for all the actual arguments.
The number of actual arguments in a macro call is denoted by $#
in the expansion text. Thus, a macro to display the number of arguments
given can be
define(`nargs', `$#') => nargs =>0 nargs() =>1 nargs(arg1, arg2, arg3) =>3
The notation $* can be used in the expansion text to denote all
the actual arguments, unquoted, with commas in between. For example
define(`echo', `$*') => echo(arg1, arg2, arg3 , arg4) =>arg1,arg2,arg3 ,arg4
Often each argument should be quoted, and the notation $@ handles
that. It is just like $*, except that it quotes each argument.
A simple example of that is:
define(`echo', `$@') => echo(arg1, arg2, arg3 , arg4) =>arg1,arg2,arg3 ,arg4
Where did the quotes go? Of course, they were eaten, when the expanded
text were reread by m4. To show the difference, try
define(`echo1', `$*') => define(`echo2', `$@') => define(`foo', `This is macro `foo'.') => echo1(foo) =>This is macro This is macro foo.. echo2(foo) =>This is macro foo.
See section Tracing macro calls, if you do not understand this.
A `$' sign in the expansion text, that is not followed by anything
m4 understands, is simply copied to the macro expansion, as any
other text is.
define(`foo', `$$$ hello $$$') => foo =>$$$ hello $$$
If you want a macro to expand to something like `$12', put a pair
of quotes after the $. This will prevent m4 from
interpreting the $ sign as a reference to an argument.
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