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JE::Scope
JavaScript scope chain

JE::Scope - JavaScript scope chain


NAME

JE::Scope - JavaScript scope chain (what makes closures work)


DESCRIPTION

JavaScript code runs within an execution context which has a scope chain associated with it. This class implements this scope chain. When a variable is accessed the objects in the scope chain are searched till the variable is found.

A JE::Scope object can also be used as global (JE) object. Any methods it does not understand will be delegated to the object at the bottom of the stack (the far end of the chain), so that $scope->null means the same thing as $scope->[0]->null.

Objects of this class consist of a reference to an array, the elements of which are the objects in the chain (the first element being the global object). (Think of it as a stack.)


METHODS

find_var($name, $value)
find_var($name)
This method searches through the scope chain, starting at the end of the array, until it finds the variable named by the first argument. If the second argument is present, it sets the variable. It then returns an lvalue (a JE::LValue object) that references the variable.

new_var($name, $value)
new_var($name)
This method creates (and optionally sets the value of) a new variable in the variable object (the same thing that JavaScript's var keyword does) and returns an lvalue.

The variable object is the first object in the scope chain (searching from the top of the stack) that is a call object, or $scope->[0] if no call object is found.


CONSTRUCTOR

None. Just bless an array reference. You should not need to do this because it is done for you by the JE and JE::Object::Function classes.


SEE ALSO

JE
the JE::LValue manpage
the JE::Object::Function manpage
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