use Perl

lib/Foo/foo.PL

and

PL_files => {
   'lib/Foo/foo.PL' => 'lib/Foo/foo.xml',
}

I saw it copy foo.xml into the blib directory, etc.

I added one more item to PL_files, re-ran Build.PL, re-ran my tests, and all of a sudden the xml files were no longer being copied into blib thus causing tests to fail.

No worries as all was well again after I added

$builder->add_build_element('xml');

• ignore differences between lower- and upper-case letters, and
• expand tabs to whitespace.

I suppose I could preprocess the strings before handing them off to is_string():

use Text::Tabs;
use Test::More tests => 1;
use Test::LongString;

# Apply one or more filters.
# N.B. The order in which the filters are applied matters:

my @strings =
    map {tr/\n\r\f / /s; $_}
    map expand($_) =>
    map lc($_)     =>
    <DATA>;

is_string(
    $strings[0],
    $strings[1],
    'Actually differs by one char'
);

__DATA__
This is a test of Test::LongStrings
this    is a    test     of Test::longstring

As far as the _common_prefix_length function is concerned, perhaps using substr would be a bit faster?

     while (length($x) && length($y)) {
-       my ($x1,$x2) = $x =~ /(.)(.*)/s;
-       my ($y1,$y2) = $y =~ /(.)(.*)/s;
+        my $x1 = substr($x, 0, 1, '');
+        my $y1 = substr($y, 0, 1, '');
        if ($x1 eq $y1) {
-           $x = $x2;
-           $y = $y2;
            ++$r;
        }

• With Inline::C, arguments to variadic C functions should be processed with Inline_Stack_Item(s), instead of the functions declared in <stdarg.h>.
• Calling Perl subroutines from C? Better start reading perlguts, perlapi, and perlcall.

I don't do any XS programming, but I do use C often enough to think learning Inline to be worthwhile and, well, fun. After my first experience with Inline, I really have to give kudos to those in /p\d+p/ who so deftly handle three disciplines (e.g, Perl, C, and XS).

My first naive attempt went something like this:

use Inline 'C';

my @integers = (4, 2, 1, 5, 6, 3);

print +choose(\&lessthan, scalar @integers, @integers);
print +choose(\&grtrthan, scalar @integers, @integers);

__DATA__
__C__

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>

int lessthan (int a, int b)
{
    return (a < b) ? a : b;
}
int grtrthan (int a, int b)
{
    return (a > b) ? a : b;
}
int choose( int(*fn)(), size_t count, int first, ...)
{
    va_list arg_ptr;
    int next;
    int keep;
    va_start(arg_ptr,count);
    keep = va_arg(arg_ptr, int);
    for(--count; count > 0; --count) {
        next = va_arg(arg_ptr, int);
        keep = fn(keep, next);
    }
    return keep;
}

In retrospect, other than as a learning exercise, this wasn't an ideal test of Inline::C. There's no speed advantage over a pure perl implementation. I ended up with something that seems to be half C and half XS:

use Inline 'C';
my @integers = (4, 2, 1, 5, 6, 3);

local $\ = "\n";
print +choose(\&lessthan, @integers);
print +choose(\&grtrthan, @integers);

__DATA__
__C__

#include <stdio.h>
#include <stdlib.h>

int lessthan (int a, int b)
{
    return (a < b) ? a : b;
}
int grtrthan (int a, int b)
{
    return (a > b) ? a : b;
}
int choose(CV *fn, int first, ...)
{
    SV *next_sv;
    SV *keep_sv;
    unsigned int count;

    Inline_Stack_Vars;

    keep_sv = newSVsv(Inline_Stack_Item(1));
    for(count = 2; count < Inline_Stack_Items ; ++count)
    {
        I32 retval;
        dSP;
        ENTER;
        SAVETMPS;
        next_sv = newSVsv(Inline_Stack_Item(count));
        PUSHMARK(SP);
        XPUSHs(sv_2mortal(newSVsv(keep_sv)));
        XPUSHs(sv_2mortal(next_sv));
        PUTBACK;
        retval = call_sv((SV *)fn, G_SCALAR);
        SPAGAIN;
        if (retval != 1)
        {
            croak("Big trouble\n");
        }
        sv_setsv(keep_sv, POPs);
        FREETMPS;
        LEAVE;
    }
    Inline_Stack_Reset;
    Inline_Stack_Done;
    return (int)SvIV(keep_sv);
}

[sunnydale:~] skuo% prove -Iblib2/lib t/*.t

t/00load.....Perl lib version (v5.8.6) doesn't match executable version (v5.8.0) at /usr/local/lib/perl5/5.8.6/darwin/Config.pm line 32.
Compilation failed in require at /usr/local/lib/perl5/5.8.6/Test/Builder.pm line 18.

It's my fault for having two different versions of perl: 5.8.6 under /usr/local/bin and Apple's default perl under /usr/bin.

It turns out that $^X is set to the string 'perl' and trips up my effort at running tests. All's well after setting HARNESS_PERL in my environment to /usr/local/bin/perl.

Perhaps one of the %Config entries should replace $^X inside Test::Harness::Straps (e.g., in &_command)?