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126 lines
4.2 KiB
Plaintext
Executable File
126 lines
4.2 KiB
Plaintext
Executable File
Design
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======
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Main assumption of the model is that the problem that we are to solve is the
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problem of the very long class names in PHP libraries. We would not attempt
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to take autoloader's job or create packaging model - only make names
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manageable.
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Namespaces are defined the following way:
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Zend/DB/Connection.php:
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<?php
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namespace Zend::DB;
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class Connection {
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}
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function connect() {
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}
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?>
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Namespace definition does the following:
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All class and function names inside are automatically prefixed with
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namespace name. Inside namespace, local name always takes precedence over
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global name. It is possible to use the same namespace in several PHP files.
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The namespace declaration statement must be the very first statement in
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file.
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Every class and function from namespace can be referred to by the full name
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- e.g. Zend::DB::Connection or Zend::DB::connect - at any time.
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<?php
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require 'Zend/Db/Connection.php';
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$x = new Zend::DB::Connection;
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Zend::DB::connect();
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?>
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Namespace or class name can be imported:
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<?php
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require 'Zend/Db/Connection.php';
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import Zend::DB;
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import Zend::DB::Connection as DbConnection;
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$x = new Zend::DB::Connection();
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$y = new DB::connection();
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$z = new DbConnection();
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DB::connect();
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?>
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import statement only defines name aliasing. It may create name alias for
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namespace or class. The simple form of statement "import A::B::C::D;" is
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equivalent to "import A::B::C::D as D;". Import statement can be used at any
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time in global scope (not inside function/class) and takes effect from the
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point of definition down to the end of file. It is recommended however to
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place imports at the beginning of the file. Import statements have effect
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only on file where they are written.
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The special "empty" namespace (:: prefix) is useful as explicit global
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namespace qualification. All class and function names started from ::
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interpreted as global. <?php namespace A::B::C;
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$con = ::mysql_connect(...);
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?>
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A special constant __NAMESPACE__ indicates the current namespace. It can be
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used to construct fully-qualified names to pass them as callbacks.
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<?php
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namespace A::B::C;
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function foo() {
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}
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set_error_handler(__NAMESPACE__ . "::foo");
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?>
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In global namespace __NAMESPACE__ constant has value of empty string.
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Names inside namespace are resolved according to the following rules.
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1) all qualified names are translated during compilation according to
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current import rules. So if we have "import A::B::C;" and then "C::D::e();"
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it is translated to "A::B::C::D::e()"
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2) unqualified class names translated during compilation according to
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current import rules. So if we have "import A::B::C;" and then "new C();" it
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is translated to "new A::B::C()"
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3) calls to unqualified functions that are defined in current namespace
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interpreted as calls to corresponding functions
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4) calls to unqualified functions that are not defined in current namespace
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are resolved in run-time. The call to function foo() inside namespace (A::B)
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first tries to find and call function from current namespace A::B::foo() and
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if it doesn't exist PHP tries to call internal function foo(). Note that
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using foo() in namespace you can call only internal PHP functions, however
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using ::foo() you are able to call any function from global namespace.
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5) unqualified class names are resolved at run-time. E.q. "new Exception()"
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first tries to use (end even __autoload()) class from current namespace and
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in case of failure uses internal PHP class. Note that using "new A" in
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namespace you can call only create internal PHP class, however using "new
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::A" you are able to create any class from global namespace
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6) Calls to qualified functions are resolved at run-time. Call to
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"A::B::foo()" first tries to call function foo() from namespace "A::B", then
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it tries to find class "A::B (__autoload() it if necessary) and call its
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static function foo()
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7) qualified class names are interpreted as class from corresponding
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namespace. So "new A::B::C()" creates class "C" from namespace "A::B".
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TODO
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====
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* Rename namespaces to packages?
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* Extend the Reflection API
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* Add ReflectionPackage class
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+ getName()
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+ getClasses()
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+ getFunctions()
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+ getFiles()
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* Add getNamespace() methods to ReflectionClass and ReflectionFunction
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* Make ext/tokenizer package-aware
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