Constructor (object-oriented programming): Difference between revisions

Revision as of 02:42, 21 April 2014

Revision as of 02:45, 21 April 2014

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In [[Eiffel (programming language)|Eiffel]], the routines which initialize new objects are called '''creation procedures'''. Creation procedures have the following traits:

* Creation procedures have no explicit return type (by definition of '''procedure''').<ref>{{Efn|Eiffel '''routines''' are either '''procedures''' or '''functions'''. Procedures never have a return type. Functions always have a return type.</ref>}}

* Creation procedures are named.

* Creation procedures are designated by name as creation procedures in the text of the class.

* Creation procedures can be explicitly invoked to re-initialize existing objects.

* Every effective (i.e., concrete or non-abstract) class must designate at least one creation procedure.

* Creation procedures must leave the newly initialized object in a state that satisfies the class invariant.<ref>{{Efn|Because the inherited class invariant must be satisfied, there is no mandatory call to the parents' constructors.</ref>}}

Although object creation involves some subtleties,<ref name="eiffel standard">[http://www.ecma-international.org/publications/standards/Ecma-367.htm Eiffel ISO/ECMA specification document]</ref> the creation of an attribute with a typical declaration <code lang="eiffel">x: T</code> as expressed in a creation instruction <code lang="eiffel">create x.make</code> consists of the following sequence of steps:

* Create a new direct instance of type <code lang="eiffel">T</code>.<ref>{{Efn|The Eiffel standard requires fields to be initialized on first access, so it is not necessary to perform default field initialization during object creation.</ref>}}

* Execute the creation procedure <code lang="eiffel">make</code> to the newly created instance.

* Attach the newly initialized object to the entity <code lang="eiffel">x</code>.

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* [[Destructor (computer science)|Destructor]]

* [[Global constructor]]

== Notes ==

{{Notelist}}

== References ==

{{reflistReflist}}

[[Category:Method (computer programming)]]