Extends another class
via a mechanism known as "parasitic inheritance".
Simply speaking this method "extends another class". What is actually
happening is that it creates an instance of class name ...className,
by taking another Object instance and add ...className to the class
list and also add all the named values in ... as fields to the
new instance.
The method should be used by the constructor of a class and nowhere else.
## S3 method for class 'Object' extend(this, ...className, ..., ...fields=NULL, ...envir=parent.frame(), ...finalize=NA)
...className |
The name of new class. |
... |
Named values representing the fields of the new instance. |
...fields |
An optional named |
...envir |
An |
...finalize |
A |
The reason for the strange name of argument "...className" is that
if one tries to set a field with a name that is a prefix of the name of
this arguments and one at the same time does not specify the name of this
argument one would run into strange errors. For instance, try
extend(Object(), "MyClass", ...c=0).
Returns an Object of class className.
It is possible to specify modifiers to some of the fields. Currently it
is only the cached modifier that is recognized. A field that is
cached will be assigned NULL when *clearCache() is called.
To specify a modifier, append a comma separated list of modifiers followed
by a colon, e.g. "cached:foo".
Henrik Bengtsson
For more information see Object.
## Not run: For a complete example see help(Object).
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