References an instance of an ABL or .NET class
and provides access to instance class members (per the restrictions
of the access levels assigned to the members).
Syntax
object-reference [ [ key ] ] [ : { data-member
| property
| method
}
]
|
-
object-reference
- Specifies a reference to an instance of a class (an object).
This can be a variable (data member), property, data member or property
array element, handle attribute (such as FIRST-OBJECT), method return
value, ABL function return, or user-defined function return value
defined for an ABL or .NET object type. It also can be an
appropriately-used system reference, such as SUPER or THIS-OBJECT.
Its value references an instance of a specified class (class-based
object). If it is for a class, the data type of the value
can be for the class type itself or for a super class of the referenced
class. If it is for an interface, its value can reference an instance
of any class that implements that interface.
- [ key ]
- Specifies an indexer for the default indexed property of a .NET class. The
brackets are a required part of the syntax.
The key value
is an index value of any supported .NET data type that identifies
the property value you want to reference. If this value is an object
reference, you can also use it to access any public instance data-member, property,
or method on the .NET class instance that
the property references. For more information, see the reference
entry for a Class-based property access.
Note: ABL also allows you to
access the default indexed property of a class by specifying the
indexer on the default property name. There is no functional difference
between specifying the indexer directly on the object reference
and specifying it on the property name. For more information on
accessing .NET indexed properties, see the
Class-based property access reference entry.
-
data-member
- Specifies the name of a PUBLIC instance variable defined in
the specified ABL class or of a public instance field defined in
the specified .NET class. The value of the ABL variable data
member can be written or read for the class instance referenced
by object-reference. The value of a .NET field
can be read or written for the class instance specified by object-reference,
unless it is defined as a constant (using the C# const keyword).
If it is a constant, it can only be read. For more information,
see the reference entry for a Class-based data member access.
-
property
- Specifies the name of a PUBLIC instance property defined in
the specified ABL or .NET class. The value of this property
can be written or read for the class instance referenced by object-reference,
depending on the property definition. For more information, see
the reference entry for a Class-based property access.
-
method
- Specifies the name and any run-time parameters taken by a PUBLIC instance
method defined in the specified ABL or .NET class, or a call
to a built-in event method. A class method can provide a value,
depending on the method definition. For more information on calling
class methods, see the reference entry for a Class-based method call. For more information on the built-in event methods,
see the Class Events Reference.
Notes
- You
can obtain an object reference for a .NET object in the same way
you can obtain a reference to any ABL class-based object, by creating a
new object or obtaining the reference to an existing one. You cannot create
or reference instances of the following .NET classes:
- Classes
defined in the .NET default namespace (that is, classes with
no namespace defined)
- System.Threading.Thread or any class derived
from it
- System.Delegate or any delegate type derived
from it
- If the documentation for a .NET class includes a member
in a list of "Explicit Interface Implementations", you cannot access
that member on an object reference defined as the class type. You
can only access that member on an object reference that is defined
as (or cast to) a particular interface that defines the method.
Thus, ABL documentation refers to such a .NET class member
as an explicit interface member.
- You cannot define or otherwise obtain an object reference to
a .NET mapped object type (for example, System.Int32), except
when overriding a .NET method or when implementing a method or
property of a .NET interface. You can only access instances
of .NET mapped object types as corresponding ABL primitive
types (for example, INTEGER). For more information, see the Data types reference
entry. However, you can access .NET static properties and
methods on their defining .NET mapped object types.
- ABL classes do not currently support default or indexed properties. So,
you cannot reference an ABL class instance using an indexer for
a default indexed property.
