[PHP-DOC] Re: namespaces docs

[Greg Beaver]

Stanislav Malyshev wrote:
> Hi!
> 
>> Shows that a namespace name with \ acts very differently from a
>> namespace name without \ in imports, so I don't think it is entirely
>> accurate to say that PHP namespaces don't support sub-namespacing.
> 
> I'm afraid I don't understand what do you mean by "sub-namespacing"
> besides the trivial fact that if you add foo, \ and bar you get foo\bar.
> Could you please explain?

I'll try :).  Aside from the import example, let's look at this code:

<?php
namespace foo;

$a = bar\buh;
?>

instantiates a class in the foo\bar namespace named buh.  In other
words, it instantiates class buh from the sub-namespace bar of namespace
foo.

This is the same as C++ nested namespaces (see the example at
http://www.java2s.com/Tutorial/Cpp/0020__Language-Basics/Anestednamespace.htm)

specifically:

<quote>
  // use MyNamespace1
  using namespace MyNamespace1;

  cout << i * MyNamespace2::j;
</quote>

which accesses:

<quote>
namespace MyNamespace1 {
  int i;
  namespace MyNamespace2 { // a nested namespace
    int j;
  }
}
</quote>

we can do something this exact thing in PHP as:

<?php
namespace MyNamespace1 {
const i = 1;
}
namespace MyNamespace1\MyNamespace2 {
const j = 2;
}
namespace MyNamespace1 {
echo i * MyNamespace2\j;
}
?>

The important line is "MyNamespace2\j" which resolves the same way as in
the C++ example.

The same principle exists in C# (from
http://msdn.microsoft.com/en-us/library/z2kcy19k(VS.80).aspx):

<quote>
using System;
namespace SomeNameSpace
{
    public class MyClass
    {
        static void Main()
        {
            Nested.NestedNameSpaceClass.SayHello();
        }
    }

    // a nested namespace
    namespace Nested
    {
        public class NestedNameSpaceClass
        {
            public static void SayHello()
            {
                Console.WriteLine("Hello");
            }
        }
    }
}
</quote>

which we can do in PHP as:

<?php
namespace SomeNameSpace {
class MyClass
{
    static function Main()
    {
        Nested\NestedNameSpaceClass::sayHello();
    }
}
}
namespace SomeNameSpace\Nested {
class NestedNameSpaceClass
{
    static function SayHello()
    {
        echo "Hello";
    }

}
}
?>

>> actually, "use \Long\Classname;" is a parse error - did we intend to
>> allow it?
> 
> I thought it was allowed, to be compatible with use \Classname. Wouldn't
> hurt to do it, I think.

This is trivial, and can be added after the bracketed namespace support
is in 5.3 (don't forget to review the patch I sent,
http://pear.php.net/~greg/bracketed.patch.txt)

Thanks,
Greg