Windows also allows / as a directory separator, which is why basename() supports 
both separators on that platform. Given that it's easy enough to write a function 
in PHP that calls explode() using \ as a delimiter and accesses the last value in 
the array, and namespaces _aren't_ the filesystem, extending basename() doesn't 
make much sense.

This has been requested in bug 32349 in 2005 already, but was rejected with:

> On unix "\name\containing\slashes" is a perfectly valid directory or file name

That is unfortunate, but indeed true.

The behavior on Windows allows to quickly retrieve the shortname of a fully-qualified class name (FQCN).

That is useful when one needs to retrieve the info from arbitrary class names, without having to instantiate a memory-intensive \ReflectionClass (triggering autoloading) and without having to invent (slow) custom helper functions.

cf. https://gist.github.com/sun/7c15ac1e6c68b1334f49

PHP introduced namespaces in 5.3, but PHP core does not provide native utility functions to retrieve

1. The shortname of a fully-qualified class name.
2. The namespace of a fully-qualified class name.

Wondering whether it would be worth to re-open this bug or create a new one to discuss the addition of two simple utility functions to http://php.net/manual/en/ref.classobj.php ?

1. string       class_shortname( string $fqcn )
2. string|false class_namespace( string $fqcn )


Expected result:
----------------
Platform: Any

FQCN                 class_namespace()  class_shortname()
-------------------- ------------------ -----------------
Name\Spaced\Class    'Name\Spaced'      'Class'
\Name\Spaced\Class   'Name\Spaced'      'Class'
Class                FALSE              'Class'
\Class               FALSE              'Class'


Not familiar with hacking C, but these two helper functions sound trivial to implement to me; possibly even backportable as minor feature additions to 5.4+ ?

Thoughts?

---

For completeness, like the OP, I originally wanted to ask whether we can move basename()'s platform-specific behavior on Windows into the regular code so that backslashes work as delimiters on all platforms...

Test script:
------------
<?php
$classes = array(
  'Name\Spaced\Class',
  '\Name\Spaced\Class',
  'Class',
  '\Class',
);
echo 'Platform: ', PHP_OS, "\n\n";
printf("%-20s %-15s %s\n", 'FQCN', 'dirname()', 'basename()');
printf("%-20s %-15s %s\n", str_repeat('-', 20), str_repeat('-', 15), str_repeat('-', 10));
while ($class = array_shift($classes)) {
  printf("%-20s %-15s %s\n", $class, dirname($class), basename($class));
}

Expected result:
----------------
Platform: - All -

FQCN                 dirname()       basename()
-------------------- --------------- ----------
Name\Spaced\Class    Name\Spaced     Class
\Name\Spaced\Class   \Name\Spaced    Class
Class                .               Class
\Class               \               Class

Actual result:
--------------
Platform: WINNT

FQCN                 dirname()       basename()
-------------------- --------------- ----------
Name\Spaced\Class    Name\Spaced     Class
\Name\Spaced\Class   \Name\Spaced    Class
Class                .               Class
\Class               \               Class

Platform: Linux

FQCN                 dirname()       basename()
-------------------- --------------- ----------
Name\Spaced\Class    .               Name\Spaced\Class
\Name\Spaced\Class   .               \Name\Spaced\Class
Class                .               Class
\Class               .               \Class