On 07/07/2018 05:29 PM, Charlie Sale wrote:
Hello M4
Hi,
I am trying to write an m4 macro that has the literal $0 character in
its expansion. Basically, I'm trying to do something like this:
define(`my_macro', `/$1/ { print $0 }')
my_macro(`foo')
--> /foo/ { print $0 }
Whenever I use the above macro, it turns into this unterminating recursive
loop that re-expands the macro in the back. I am aware that the token
$0 prints the name of the defined macro in M4, but I would like to print
the literal characters instead. How can I do this?
Does the following do what you want?
define(`my_macro', `/$1/ { print $`'0 }')
Each additional `' delays expansion until the next round of parsing. So
you could end up with something like this:
define(`my_macro', `/$1/ { print $````''''0 }')
What happens is the inner most `' is removed each parse cycle. So the
above would only expand $0 on the 5th parsing cycle. (If you had that
many.)
At least that's my understanding. -- Grant. . . . unix || die
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