M4 has some well-known uses like Sendmail and GNU Autoconf, but I don’t think this can be counted in M4’s favor: For operating in a standard Unix-like environment, there is really no good alternative to m4 for generic text macro expansion. You can try to force cpp – the C preprocessor – into this, but it is really only suited to being part of a C compiler pipeline. For better or for worse, m4 is it in the world of Unix and shell tools, even though its syntax is quite annoying to use.
Of course, if you operate within a language ecosystem, you can probably find a nice templating system there. Python, for instance, has Jinja2. Or, if your needs are simple, you can use something more basic, like sed(1).
> M4 syntax looks that way because it has to work for arbitrary text files.
That seems like an odd assertion given the existence of other templating systems which have friendlier syntax while being capable of generating arbitrary output. Is there a reason why you think on the M4 approach is valid?
Most templating systems work in combination with an external program written in a high-level language, e.g. Ruby for Liquid or Python for jinja2. m4 does not.
And m4 works in combination with a bunch of C code. Virtually any system with m4 can come with an interpreter for a higher level language without running out of space (I can't imagine many uses for m4 at runtime on systems where, say, a perl interpreter wouldn't fit). Why is relying on such a runtime a problem?
What does “autonomous” mean? There are a ton of template engines that don’t depend on a parent framework, there is no reason you can’t implement all features in C.
Jinja2 is an API and it needs a Python program to determine the values for the substitution variable and invoke the template engine. In contrast the M4 executable is the engine.
I use PHP when I need non-trivial templating. Always struck me as odd that people would invent/use their own templating engines (think HCL, jinja, smarty, m4). All of these are implementable as either a PHP file or a haskell interface
Of course, if you operate within a language ecosystem, you can probably find a nice templating system there. Python, for instance, has Jinja2. Or, if your needs are simple, you can use something more basic, like sed(1).
(Repost: https://news.ycombinator.com/item?id=22770406)