[Module-build-general] redirecting system() to a file, or ways to avoid it

[Ken W. <ke...@ma...>]

Hey,

In Module::Build, very little is done by the external system, but some 
things still are.  One little thorn in its side is ExtUtils::xsubpp - 
which, despite living in @INC and having two colons in its name, is a 
script, not a module.  In order to parse .xs files, this script needs to 
be called and its output redirected to a file.

That's not usually a very hard task, but I've decided to use the 
multi-arg form of system() whenever possible, so that I don't have to 
handle argument quoting issues on all the platforms of the world.  But 
the multi-arg form of system() doesn't let me do output redirects (which 
probably weren't portable across platforms anyway with single-arg 
system()).

So I'm trying to think of the best alternative.  Choices include:

  1) Wrap all of the xsubpp code into a subroutine, set @ARGV, open 
STDOUT to a file, and call the subroutine.

  2) Same as 1), but just do() the xsubpp file instead of making it a 
subroutine.

  3) Write some function to convert multi-arg system() calls to 
safely-quoted single-arg system() calls, in a cross-platform way, with 
cross-platform support for output redirection.

  4) Go back in time and re-implement ExtUtils::xsubpp as a bare-bones 
wrapper around an ExtUtils::ParseXS module.  Module::Build can just call 
functions in ExtUtils::ParseXS, then.

  5) Don't go back in time, but create an ExtUtils::ParseXS module 
nonetheless, which *future* versions of xsubpp could use as guts.  
Create a Module::Build dependency on ExtUtils::ParseXS and don't call 
xsubpp.

  6) Borg all the xsubpp code into Module::Build where I can control it.


Even though 1) and 2) are pretty ugly, I'm leaning toward doing one of 
them, if they'd work.  3) looks non-fun, and the further away I can get 
Module::Build and system() from each other, the better.  4) and 5) would 
be a lot of work, but probably the best from an architectural point of 
view.  4) would be really cool, actually.  Note that 5) would create the 
first non-5.6-core dependency in Module::Build, though.  And 6) seems 
like a bad idea.

There's also:

  7) Just write it as a single-arg, ad hoc system() call, don't worry 
about cross-platform issues, make those MacOS bastards live without XS 
compilation a little while longer, and only fix the quoting when someone 
tells me it's broken on VMS and Amiga, and Win95.

Any thoughts before I act?

  -Ken