diff --git a/README.namespaces b/README.namespaces new file mode 100755 index 00000000000..c640762796c --- /dev/null +++ b/README.namespaces @@ -0,0 +1,103 @@ +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: + + +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. It is possible to use the same namespace in several PHP files. +The namespace declaration statement must be the very first statement in +file. + +Every class and function from namespace can be referred to by the full name +- e.g. Zend::DB::Connection or Zend::DB::connect - at any time. + + + +Namespace or class name can be imported: + + + +import statement only defines name aliasing. It may create name alias for +namespace or class. The simple form of statement "import A::B::C::D;" is +equivalent to "import A::B::C::D as D;". Import statement can be used at any +time in 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 imports at the beginning of the file. Import statements have effect +only on file where they are written. + +The special "empty" namespace (:: prefix) is useful as explicit global +namespace qualification. All class and function names started from :: +interpreted as global. + +A special constant __NAMESPACE__ indicates the current namespace. It can be +used to construct fully-qualified names to pass them as callbacks. + + + +In global namespace __NAMESPACE__ constant has 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 "import 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 "import A::B::C;" and then "new C();" it +is translated to "new A::B::C()" + +3) calls to unqualified functions that are defined in current namespace +interpreted as calls to corresponding functions +4) calls to unqualified functions that are not defined in current namespace +are resolved in 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() in namespace you can call only internal PHP functions, however +using ::foo() you are able to call any function from global namespace. +5) unqualified class names are resolved at run-time. E.q. "new Exception()" +first tries to use (end even __autoload()) class from current namespace and +in case of failure uses internal PHP class. Note that using "new A" in +namespace you can call only create internal PHP class, however using "new +::A" you are able to create any class from 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 function foo() +7) qualified class names are interpreted as class from corresponding +namespace. So "new A::B::C()" creates class "C" from namespace "A::B". \ No newline at end of file