[PATCH] Namespace Patch, Beta 1

This sounds awesome. Good job, Jessie. Keep it up!

• David

-----Original Message-----
From: Jessie Hernandez [mailto:jrhernandez05@gmail.com]
Sent: Tuesday, August 02, 2005 6:07 AM
To: internals@lists.php.net
Subject: [PHP-DEV] [PATCH] Namespace Patch, Beta 1

Attached is the latest version of the namespace patch! It finally includes
namespace imports and it even includes anonymous namespace support. Also,
the previous bison shift/reduce conflict has been removed. Here is a
summary of its features:

• Simple imports: import ns:class1;
• Import aliases: import ns:class1 as my_alias;
• Namespace imports: import namespace ns;
• Anonymous namespaces: namespace { class file_class{} }
• Namespace-private classes: namespace ns{ private class prv_class{} }

Two new functions have also been added to support namespace imports (more
on
that below):

• get_imported_namespaces([$className])
  Returns an array of imported namespaces for the current file. If a class
  name is passed, and this class is currently being autoloaded (also meaning
  that this function is called inside __autoload), then the list of returned
  imported namespaces is based on the file that triggered the __autoload
  call.

• autoload_import_class($className, $namespaceName)
  Imports a class in a given namespace for the currently executing file (can
  ONLY be used inside __autoload!)

Imports

Imports and namespace imports are handled completely by the user with the
use of the __autloload function. This means that there are no restrictions
on class file naming/directory structure. For simple imports, the class
name will be passed with its full name (including the colons, such as
"ns:class1"). For namespace imports, only the class name will be called.
Since the user needs to determine which namespace (or namespaces) a class
belongs to, the "get_imported_namespaces" function is provided to check
the
imported namespaces for the currently-executing file. Once the user is
satisfied with a match, he/she needs to perform an "import" for this
class,
but this needs to be done on the executing file, not the file where
__autoload is defined. For this reason, the autoload_import_class function
is provided. A sample usage of both these functions is at
tests/classes/namespace_autoload.php.

Namespace-private classes

Classes marked as "private" from within a namespace can only be used by
classes defined in the same namespace.

Anonymous namespaces

Classes defined inside anonymous namespaces can only be used within the
file
that declared the anonymous namespace.

I believe the attached patch solves the issues that were presented long
ago
for namespaces. Referring to the post by Daniel Cogwill at
http://www.zend.com/lists/engine2/200304/msg00164.html, the following are
my answers to the problems he found at the time:

1. import-all silently hides local names.
   A: If a global class is defined with the same name as a class in a
   namespace, and the namespace class has been imported in the same script,
   the global class takes precedence. The namespace class can still be used
   by
   using its full name, i.e. namespace_name:class_name.

2. Interestingly (and I assume this is simply a bug), functions and
   classes
   behave differently wrt to import-all and duplicate definitions.
   A: Irrelevant in this patch.

3. There is no way to hide names from import (i.e. make a name
   non-exportable). This is a fundamental namespace feature, and there is
   already an appropriate keyword (private).
   A: Namespace-private classes are supported, using the "private" keyword.

4. The semantic meaning of successive imports depends on their relative
   ordering.
   A: The engine does not attempt to determine which class is included, the
   user decides the most appropriate behavior inside __autoload.

5. The most egregious issue is that an import in an included file affects
   the scope of the including file.
   A: Imports in this patch only affect the file they are in.

Since I could not find a way to add the tests/classes/namespace directory
and subdirectories, I zipped them separately, as before.

Let me know if you have any questions on the attached patch.

Best regards,

Jessie Hernandez

Jessie Hernandez wrote:

Attached is the latest version of the namespace patch! It finally includes
namespace imports and it even includes anonymous namespace support. Also,
the previous bison shift/reduce conflict has been removed. Here is a
summary of its features:

• Simple imports: import ns:class1;
• Import aliases: import ns:class1 as my_alias;
• Namespace imports: import namespace ns;
• Anonymous namespaces: namespace { class file_class{} }
• Namespace-private classes: namespace ns{ private class prv_class{} }

Two new functions have also been added to support namespace imports (more on
that below):

• get_imported_namespaces([$className])
  Returns an array of imported namespaces for the current file. If a class
  name is passed, and this class is currently being autoloaded (also meaning
  that this function is called inside __autoload), then the list of returned
  imported namespaces is based on the file that triggered the __autoload
  call.

so, if I understand correctly, if your __autoload is defined in a
different file(file1) from where the import was
called(file2), then get_imported_namespaces() returns the namespace
imports for file1.
get_imported_namespaces($className) would return for file2, and outside
of the __autoload function,
get_imported_namespaces($className) would return the namespaces for
file1. That seems like
complicated semantics. Is there some way this could be simplified? Maybe
there should be two functions,
one that returns namespaces for file2 and is incorrect(throws an error)
to call from anywhere other than
__autoload(), and one that returns namespaces for file2.

• autoload_import_class($className, $namespaceName)
  Imports a class in a given namespace for the currently executing file (can
  ONLY be used inside __autoload!)

Imports

Imports and namespace imports are handled completely by the user with the
use of the __autloload function. This means that there are no restrictions
on class file naming/directory structure. For simple imports, the class
name will be passed with its full name (including the colons, such as
"ns:class1"). For namespace imports, only the class name will be called.
Since the user needs to determine which namespace (or namespaces) a class
belongs to, the "get_imported_namespaces" function is provided to check the
imported namespaces for the currently-executing file. Once the user is
satisfied with a match, he/she needs to perform an "import" for this class,

This seems like it would be slow, as the user might have many
namespaces(directories) to search for matching
files. This would of course be up to the user. And it doesn't bother me
that a full namespace import
may not be as fast as a more specific import. In development it might be
convenient, but at some point, it's not
that big a deal to specify the classes you use.

but this needs to be done on the executing file, not the file where
__autoload is defined. For this reason, the autoload_import_class function
is provided. A sample usage of both these functions is at
tests/classes/namespace_autoload.php.

I like the option of having namespaces, and from the description this
seems to be a light method of doing it. It does
require some effort from the user. It seems that for most cases
__autoload will be the same every time, maybe with
different paths or file naming conventions.

John

FYI, I haven't had a chance to look at this patch yet (nor a lot of the
emails on the subject). After PHP 5.1 goes RC and we start our Unicode
work, I should have time to look into it. Interesting to see if it
addresses the issues we had in the past. I think some of them weren't
solvable although if this only addresses classes it might have. One note,
we need to make sure we don't complicate the language too much... But
anyway, hopefully next week or so I'll have more constructive feedback.

At 12:07 AM 8/2/2005 -0400, Jessie Hernandez wrote:

Attached is the latest version of the namespace patch! It finally includes
namespace imports and it even includes anonymous namespace support. Also,
the previous bison shift/reduce conflict has been removed. Here is a
summary of its features:

• Simple imports: import ns:class1;
• Import aliases: import ns:class1 as my_alias;
• Namespace imports: import namespace ns;
• Anonymous namespaces: namespace { class file_class{} }
• Namespace-private classes: namespace ns{ private class prv_class{} }

Two new functions have also been added to support namespace imports (more on
that below):

• get_imported_namespaces([$className])
  Returns an array of imported namespaces for the current file. If a class
  name is passed, and this class is currently being autoloaded (also meaning
  that this function is called inside __autoload), then the list of returned
  imported namespaces is based on the file that triggered the __autoload
  call.

• autoload_import_class($className, $namespaceName)
  Imports a class in a given namespace for the currently executing file (can
  ONLY be used inside __autoload!)

Imports

Imports and namespace imports are handled completely by the user with the
use of the __autloload function. This means that there are no restrictions
on class file naming/directory structure. For simple imports, the class
name will be passed with its full name (including the colons, such as
"ns:class1"). For namespace imports, only the class name will be called.
Since the user needs to determine which namespace (or namespaces) a class
belongs to, the "get_imported_namespaces" function is provided to check the
imported namespaces for the currently-executing file. Once the user is
satisfied with a match, he/she needs to perform an "import" for this class,
but this needs to be done on the executing file, not the file where
__autoload is defined. For this reason, the autoload_import_class function
is provided. A sample usage of both these functions is at
tests/classes/namespace_autoload.php.

Namespace-private classes

Classes marked as "private" from within a namespace can only be used by
classes defined in the same namespace.

Anonymous namespaces

Classes defined inside anonymous namespaces can only be used within the file
that declared the anonymous namespace.

I believe the attached patch solves the issues that were presented long ago
for namespaces. Referring to the post by Daniel Cogwill at
http://www.zend.com/lists/engine2/200304/msg00164.html, the following are
my answers to the problems he found at the time:

1. import-all silently hides local names.
   A: If a global class is defined with the same name as a class in a
   namespace, and the namespace class has been imported in the same script,
   the global class takes precedence. The namespace class can still be used by
   using its full name, i.e. namespace_name:class_name.

2. Interestingly (and I assume this is simply a bug), functions and classes
   behave differently wrt to import-all and duplicate definitions.
   A: Irrelevant in this patch.

3. There is no way to hide names from import (i.e. make a name
   non-exportable). This is a fundamental namespace feature, and there is
   already an appropriate keyword (private).
   A: Namespace-private classes are supported, using the "private" keyword.

4. The semantic meaning of successive imports depends on their relative
   ordering.
   A: The engine does not attempt to determine which class is included, the
   user decides the most appropriate behavior inside __autoload.

5. The most egregious issue is that an import in an included file affects
   the scope of the including file.
   A: Imports in this patch only affect the file they are in.

Since I could not find a way to add the tests/classes/namespace directory
and subdirectories, I zipped them separately, as before.

Let me know if you have any questions on the attached patch.

Best regards,

Jessie Hernandez

Jesse,
another thing to consider (if you havent already) is extension support.
IOW, how do i place my extension-created class into a namespace. Is this as
simple as declaring the class name as Ns:Class ?

l0t3k