Re: Embedding vs. Extending

[ludo@gnu.org (Ludovic Courtès)]

Hi!

Paul Smith <psmith@gnu.org> skribis:

> On Sun, 2011-09-18 at 14:10 +0200, Ludovic Courts wrote:
>> Ideally, when Guile support is enabled, GNU make would be turned into
>> a Guile extension (a shared library and its companion Scheme module
>> that loads it with ‘load-extension’) that would expose make’s
>> functionality.

[...]

> A technically acceptable option would be to build GNU make in two forms:
> first a standalone application that worked as now, and second a
> "library" that could be linked as a Guile extension.

Yes.

> However, from what I've read of Guile that would be an immense amount of
> work: GNU make was created over 20 years ago and has a lot of
> not-completely-clean features and implementation details which rely on
> it being a stand-alone program.  There's massive amounts of global
> memory usage, not even a nod to threading capabilities or locking, and
> features like automatically re-exec'ing itself in some situations.

Yeah, widespread use of global variables and such is likely to make a
hypothetical ‘make’ library much less useful.

> Finally, while it's a cool idea I'm not sure there's a compelling need
> for this.

Here’s an example: DMake [0] is concerned with makefile task scheduling
on distributed architectures.  To do that, it needs to know the DAG of
tasks defined in a makefile.  To achieve that, it ends up parsing the
output of ‘make -ptq’; it works, but it’s fragile (has to use the C
locale, is sensitive to formatting changes, etc.), and suboptimal.

Imagine if this could be achieved simply by having DMake directly call
make’s library functions to get the data it needs.

[0] http://dmake.ligforge.imag.fr/


Another example: many projects have make-like functionality built-in.
For instance, Java compilers (ahem...) have dependency tracking
built-in; Rubber [1] automatically infers dependencies from LaTeX source
files and runs the right actions in the right order; Guile’s
auto-compilation feature is a simple .scm → .go rule; and so on.

[1] https://launchpad.net/rubber


I could probably come up with others if you’re curious.  ;-)


> My main purpose is to add some kind of scripting capability to GNU make
> to augment the current functions capability.

And this is a worthy goal too!

Thanks,
Ludo’.