NSPortCoder

Inherits From:
NSCoder : NSObject

Conforms To:
NSObject (NSObject)

Declared In:
Foundation/NSPortCoder.h

Class Description

Making Substitutions During Encoding

The generic classForCoder: method is most useful for mapping private subclass hierarchies through a public superclass, which (for example) aids the stability of archives when subclasses are private or subject to change. Since processes communicating at run time typically use the same version of a class library, this mapping is often not needed in distributed objects communication. classForPortCoder: allows an object to bypass or override the generic classForCoder: behavior, sending its real class (or simply a different one from the generic case) to the communicating process or thread. If you implement a group of classes that use the generic classForCoder: method, you should also consider using classForPortCoder: to handle the special case of encoding with the distributed objects system.

The generic replacementObjectForCoder: method offers a standard way to substitute a different instance at encoding time. replacementObjectForPortCoder: specifically allows for the substitution of proxies over a distributed objects connection. The receiver of a replacementObjectForPortCoder: message can ask the NSPortCoder whether it should be encoded bycopy or not, and return itself or a proxy as appropriate. NSObject's implementation always returns a proxy, so subclasses that allow bycopy encoding should override replacementObjectForPortCoder: to perform at least as this sample does:

- (id)replacementObjectForPortCoder:(NSPortCoder *)encoder
{
    if ([encoder isBycopy]) return self;
    return [super replacementObjectForPortCoder:encoder];
}

If the NSPortCoder returns YES when sent an isBycopy message, this example method returns self, which will result in the receiver being sent an encodeWithCoder: message. If the NSPortCoder returns NO, this method invokes the superclass's implementation, which typically returns an NSDistantObject.

Creating an NSPortCoder

portCoderWithReceivePort:sendPort:components:

Getting the NSConnection

- connection

Encoding NSPort objects

- encodePortObject:

- decodePortObject

Checking for encoding

- isBycopy

- isByref

Dispatching

- dispatch

Class Methods

portCoderWithReceivePort:sendPort:components:

<< Description forthcoming. >>

Instance Methods

connection

Returns the NSConnection object that uses the NSPortCoder. In an object's encodeWithCoder: method, this is the sending (server) NSConnection. In initWithCoder: this is the receiving (client) NSConnection.

decodePortObject

Decodes and returns an NSPort object that was previously encoded with any of the general encode...Object: messages. This method is primarily for use by NSPort objects themselves; you can always use decodeObject to decode any object.

NSPort invokes this method in its initWithCoder: method so that the appropriate kernel information for the port can be decoded. A subclass of NSPortCoder shouldn't decode an NSPort by sending it an initWithCoder: message. See ""Creating a Subclass of NSCoder"" in the NSCoder class specification for more informaton.

dispatch

<< Description forthcoming. >>

encodePortObject:

Encodes aPort so that it can be properly reconstituted in the receiving process or thread. This method is primarily for use by NSPort objects themselves; you can always use the general encode...Object: methods to encode any object.

NSPort invokes this method in its encodeWithCoder: method so that the appropriate kernel information for the port can be encoded. A subclass of NSPortCoder shouldn't encode an NSPort by sending it an encodeWithCoder: message. See ""Creating a Subclass of NSCoder"" in the NSCoder class specification for more informaton.

isBycopy

Returns YES if the NSPortCoder is encoding an object bycopy, NO if it expects a proxy. You typically use this method in replacementObjectForPortCoder: to decide whether to substitute a proxy. See ""Making Substitutions During Encoding"" in the class description for more information.

isByref

<< Description forthcoming. >>