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author | Lorry Tar Creator <lorry-tar-importer@baserock.org> | 2013-03-14 05:42:27 +0000 |
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committer | <> | 2013-04-03 16:25:08 +0000 |
commit | c4dd7a1a684490673e25aaf4fabec5df138854c4 (patch) | |
tree | 4d57c44caae4480efff02b90b9be86f44bf25409 /README.namespaces | |
download | php2-master.tar.gz |
Imported from /home/lorry/working-area/delta_php2/php-5.4.13.tar.bz2.HEADphp-5.4.13master
Diffstat (limited to 'README.namespaces')
-rwxr-xr-x | README.namespaces | 174 |
1 files changed, 174 insertions, 0 deletions
diff --git a/README.namespaces b/README.namespaces new file mode 100755 index 0000000..9c427b6 --- /dev/null +++ b/README.namespaces @@ -0,0 +1,174 @@ +Design +====== + +Main assumption of the model is that the problem that we are to solve is the +problem of the very long class names in PHP libraries. We would not attempt +to take autoloader's job or create packaging model - only make names +manageable. + +Namespaces are defined the following way: + +Zend/DB/Connection.php: +<?php +namespace Zend\DB; + +class Connection { +} + +function connect() { +} +?> + +Namespace definition does the following: +All class and function names inside are automatically prefixed with +namespace name. Inside namespace, local name always takes precedence over +global name. Several files may be using the same namespace. +The namespace declaration statement must be the very first statement in +the file. The only exception is "declare" statement that can be used before. + +Every class and function in a namespace can be referred to by the full name +- e.g. Zend\DB\Connection or Zend\DB\connect - at any time. + +<?php +require 'Zend/Db/Connection.php'; +$x = new Zend\DB\Connection; +Zend\DB\connect(); +?> + +Namespace or class name can be imported: + +<?php +require 'Zend/Db/Connection.php'; +use Zend\DB; +use Zend\DB\Connection as DbConnection; + +$x = new Zend\DB\Connection(); +$y = new DB\connection(); +$z = new DbConnection(); +DB\connect(); +?> + +The use statement only defines name aliasing. It may create name alias for +namespace or class. The simple form of statement "use A\B\C\D;" is +equivalent to "use A\B\C\D as D;". The use statement can be used at any +time in the global scope (not inside function/class) and takes effect from +the point of definition down to the end of file. It is recommended however to +place the use statements at the beginning of the file. The use statements have +effect only on the file where they appear. + +The special "empty" namespace (\ prefix) is useful as explicit global +namespace qualification. All class and function names started from \ +interpreted as global. + +<?php +namespace A\B\C; + +$con = \mysql_connect(...); +?> + +A special constant __NAMESPACE__ contains the name of the current namespace. +It can be used to construct fully-qualified names to pass them as callbacks. + +<?php +namespace A\B\C; + +function foo() { +} + +set_error_handler(__NAMESPACE__ . "\foo"); +?> + +In global namespace __NAMESPACE__ constant has the value of empty string. + +Names inside namespace are resolved according to the following rules: + +1) all qualified names are translated during compilation according to +current import rules. So if we have "use A\B\C" and then "C\D\e()" +it is translated to "A\B\C\D\e()". +2) unqualified class names translated during compilation according to +current import rules. So if we have "use A\B\C" and then "new C()" it +is translated to "new A\B\C()". +3) inside namespace, calls to unqualified functions that are defined in +current namespace (and are known at the time the call is parsed) are +interpreted as calls to these namespace functions. +4) inside namespace, calls to unqualified functions that are not defined +in current namespace are resolved at run-time. The call to function foo() +inside namespace (A\B) first tries to find and call function from current +namespace A\B\foo() and if it doesn't exist PHP tries to call internal +function foo(). Note that using foo() inside namespace you can call only +internal PHP functions, however using \foo() you are able to call any +function from the global namespace. +5) unqualified class names are resolved at run-time. E.q. "new Exception()" +first tries to use (and autoload) class from current namespace and in case +of failure uses internal PHP class. Note that using "new A" in namespace +you can only create class from this namespace or internal PHP class, however +using "new \A" you are able to create any class from the global namespace. +6) Calls to qualified functions are resolved at run-time. Call to +A\B\foo() first tries to call function foo() from namespace A\B, then +it tries to find class A\B (__autoload() it if necessary) and call its +static method foo() +7) qualified class names are interpreted as class from corresponding +namespace. So "new A\B\C()" refers to class C from namespace A\B. + +Examples +-------- +<?php +namespace A; +foo(); // first tries to call "foo" defined in namespace "A" + // then calls internal function "foo" +\foo(); // calls function "foo" defined in global scope +?> + +<?php +namespace A; +new B(); // first tries to create object of class "B" defined in namespace "A" + // then creates object of internal class "B" +new \B(); // creates object of class "B" defined in global scope +?> + +<?php +namespace A; +new A(); // first tries to create object of class "A" from namespace "A" (A\A) + // then creates object of internal class "A" +?> + +<?php +namespace A; +B\foo(); // first tries to call function "foo" from namespace "A\B" + // then calls method "foo" of internal class "B" +\B\foo(); // first tries to call function "foo" from namespace "B" + // then calls method "foo" of class "B" from global scope +?> + +The worst case if class name conflicts with namespace name +<?php +namespace A; +A\foo(); // first tries to call function "foo" from namespace "A\A" + // then tries to call method "foo" of class "A" from namespace "A" + // then tries to call function "foo" from namespace "A" + // then calls method "foo" of internal class "A" +\A\foo(); // first tries to call function "foo" from namespace "A" + // then calls method "foo" of class "A" from global scope +?> + +TODO +==== + +* Support for namespace constants? + +* performance problems + - calls to internal functions in namespaces are slower, because PHP first + looks for such function in current namespace + - calls to static methods are slower, because PHP first tries to look + for corresponding function in namespace + +* Extend the Reflection API? + * Add ReflectionNamespace class + + getName() + + getClasses() + + getFunctions() + + getFiles() + * Add getNamespace() methods to ReflectionClass and ReflectionFunction + +* Rename namespaces to packages? + |