View source for CLASS - Scoping

From Recital Documentation Wiki

← CLASS - Scoping

You do not have permission to edit this page, for the following reason:

---

You can view and copy the source of this page:

=CLASS - Scoping= ==Class== Objects ==Purpose== Specify scoping in user-defined class ==Syntax== LOCAL | PRIVATE | PUBLIC | STATIC [NOTIFY] [PROPAGATE] : ==See Also== [[ADDPROPERTY()]], [[CLASS]], [[CLASS – METHODS]], [[CLASS – PARAMETERS]], [[CLASS – PROPERTIES]], [[CREATEOBJECT()]], [[DEFINE CLASS]], [[DODEFAULT()]], [[METHOD]], [[NEWOBJECT()]], [[REMOVEPROPERTY()]] ==Description== The visibility of the properties of an object is governed by their scope. The default visibility is public, but this can be changed by using one of the scoping commands. Once the scope is changed, it remains in effect on all property and method definitions that follow, until it is changed again or the ENDCLASS command is reached. {| class="wikitable" !Scope||Description |- |LOCAL||Local properties and methods are visible only to the object where they are defined. |- |PRIVATE||Private properties and methods are visible only to the object where they are defined and to all methods and properties of objects called by the object. |- |PUBLIC||Public properties and methods are visible everywhere. |- |STATIC||Static property values are shared by all objects of the same class. |- |} ====NOTIFY==== The Recital/4GL supports what is known as Property notification. If you specify the NOTIFY clause all properties defined will have 'notify' set. Property notification is an essential element in the real-time interaction with system objects. When a property that has been defined with the NOTIFY clause is read, and the class contains a method called GETPROPERTY, that method is called. The property name is passed to the GETPROPERTY method as a parameter. When a property that has been defined with the NOTIFY clause is updated, and the class contains a method called SETPROPERTY, that method is called. The property name and the new value are passed to the SETPROPERTY method as parameters. ====PROPAGATE==== Any methods called, which have the PROPAGATE attribute set, cause a cascading execution effect down through the class hierarchy. After the method is executed, a search is made in all of the sub-objects (if any) that are defined as properties within the current object. If a method with the same name is found and that method has the NOTIFY attribute specified, then that method is called. The CONSTRUCTOR and the DESTRUCTOR methods always act as if sub-objects have the PROPAGATE and the NOTIFY attributes set. This means that any properties that have been specified as sub-objects operate correctly when an object is created with the NEW operator. ====:==== The colon (:) is used to terminate the property scoping command. All properties following will now have the visibility of the specified scoping command, until a new scoping command is specified or the ENDCLASS is reached. ==Example== <code lang="recital"> // Use of Scope Options class myclass public: property cPUBLIC_PROPERTY method Show && Publicly available method //... return && Show private: property cPRIVATE_PROPERTY local: property cLOCAL_PROPERTY static: property cSTATIC_PROPERTY endclass oMyObj = New myclass() display memory </code> ==Products== Recital Database Server, Recital Mirage Server, Recital Terminal Developer [[Category:Documentation]] [[Category:Commands]]

Return to CLASS - Scoping.