parrot_config RFC

[James E Keenan]

Andy Dougherty wrote:
> On Tue, 23 Jun 2009, Jeff Horwitz wrote:
> 
>> On Mon, 22 Jun 2009, James E Keenan wrote:
>>
>>> Since jhorwitz asked me about this just now at YAPC|10 Parrot BOF, a data
>>> point:
>>>
>>> ./parrot_config --dump | grep '$('
[snip]
>>> libparrot => '$(LIBPARROT_SHARED)'
>>> libparrot_shared => 'libparrot$(SHARE_EXT).$(SOVERSION)'
>>> libparrot_shared_alias => 'libparrot$(SHARE_EXT)'
>>> libparrot_soname => '-Wl,-soname=libparrot$(SHARE_EXT).$(SOVERSION)'
[snip]
> 
> The remaining ones (libparrot, libparrot_shared, libparrot_shared_alias,
> and libparrot_soname) look to me as if they can (and should) simply be
> expanded by Configure.pl in the first place.
> 

Let me see if I understand what expansion by Configure.pl would entail.

Let's look at just one of these Make variables:  $(SHARE_EXT)

grepping the config/ directory, I get:

$ fns config | xargs grep -n share_ext
config/init/hints/darwin.pm:49:        share_ext           => '.dylib',
config/init/hints/darwin.pm:71:            . $conf->data->get('share_ext')
config/init/hints/mswin32.pm:75:            share_ext  => '.dll',
config/init/hints/mswin32.pm:129:            share_ext  => '.dll',
config/init/hints/mswin32.pm:171:            share_ext => '.dll',
config/init/defaults.pm:139:        share_ext => ".$Config{so}",    # 
shared library extension
config/gen/makefiles/root.in:125:SHARE_EXT        := @share_ext@
config/gen/config_pm/myconfig.in:16:    share_ext='@share_ext@', 
ld_share_flags='@ld_share_flags@',
config/gen/config_h/config_h.in:26:#define PARROT_SHARE_EXT 
"@share_ext@"

I interpret this to mean:
1.  Our old nemesis, the %Config associated with the Perl 5 used to 
invoke Configure.pl, is consulted by init::defaults to define 'share_ext'.
2.  On 2 OSes, darwin and mswin32, this is overridden by their 
respective init::hints files.
3.  The content of 'share_ext' in the Parrot::Configure object is then 
assigned or used, in configuration step order:
a.  as the value of PARROT_SHARE_EXT in the gen::config_h template;
b.  as the value of SHARE_EXT in the gen::makefiles root template;
c.  as the value of share_ext in the gen::config_pm myconfig template.

To further partialize the problem, let's consider only (3a) above.  It 
seems to me that instead of having a line in the template file 
config_h.in which, in effect, hands the interpolation of 'share_ext' 
over to 'make', what we need to do is to somehow have gen::config_h 
write that one particular line in config.h.

Am I on the right track?  Messing with those makefile templates doesn't 
seem very elegant or maintainable to me, at first glance.

kid51