ActionScript 3 Language Specification

ActionScript 3.0 Language Specification > 5 Names > 5.3 Name lookup > 5.3.1 Object references

5.3.1 Object references

Object references result from expressions involving the dot or bracket operators. They may be qualified or unqualified. The following table shows various forms of object references.

We use the expression form of references to describe the name lookup semantics. However, every literal name can be rewritten as an expression name through the following steps:

• If the expression is an unqualified literal name, then replace the dot operation o.id with a bracket operations of the form o['id']
• Otherwise, the expression is a qualified literal name, so replace the operand of the dot operation with the dot operation o.q::['id']

5.3.1.1 Unqualified object references

The unqualified expression o[expr] is a reference to a property of the value of the expression o that has a name that matches one of the names of the set of names (multiname) composed in the following way:

• Let id be the string value of the expression expr
• Let m be an empty set of names
• For each namespace q in the set of open namespaces:
  • Let n be a name with the qualifier q and the identifier id
  • Add n to the set of names m
• Return m

The single name of a multiname reference r is determined by the following steps:

• Let t be the least derived type of x that contains at least one of the names in the multiname set m of the reference r
• Let m' be the intersection of the set of names m and the property names in t
• Let n be the set of names in the most derived type of x and in m'
• If n is empty, return the name in m that is qualified by the public namespace
• If n contains one name, then return that name
• Report an ambiguous reference error

The base object of this reference is the value of the expression o.

Qualified object references

o.q::[expr]

This is a reference to a property inside the value of o that matches a single name. Because the qualifier is explicit, the qualified name is straightforward to compute:

• Let ns be the value of the expression q
• Let id be the string value of the expression expr
• Return the qualified name consisting of the namespace ns and the identifier id

The base object of this reference is the value of the expression o.

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