samer@0: /*
samer@0:  *	Variable.java	
samer@0:  *
samer@0:  *	Copyright (c) 2000, Samer Abdallah, King's College London.
samer@0:  *	All rights reserved.
samer@0:  *
samer@0:  *	This software is provided AS iS and WITHOUT ANY WARRANTY; 
samer@0:  *	without even the implied warranty of MERCHANTABILITY or 
samer@0:  *	FITNESS FOR A PARTICULAR PURPOSE.
samer@0:  */
samer@0: 
samer@0: package	samer.core;
samer@0: import	samer.core.Environment.Autocoder;
samer@0: import	java.io.*;
samer@0: 
samer@0: /**
samer@0: 	A Variable is a Viewable with an associated mutable data 
samer@0: 	model (that implements the Autocoder interface). The data
samer@0: 	model handles conversion of data to and from a small number of
samer@0: 	recognised interchange formats (String, character stream).
samer@0: 	This means that the data can be stored in a Binding.
samer@0: 
samer@0: 	The init() method handles registration of the Viewable
samer@0: 	and initialisation of the data value from a Shell property.
samer@0: 
samer@0:  */
samer@0: 
samer@0: public class Variable extends Viewable // implement Environment.Autocoder
samer@0: {
samer@0: 	/** Means do not automatically load value from current
samer@0: 		environment on construction. */
samer@0: 	public final static int	NOINIT	= 1;
samer@0: 
samer@0: 	/** Means register this Viewable automatically on construction. */
samer@0: 	public final static int	REGISTER	= 2;
samer@0: 
samer@0: 	  /** Not currently used. */
samer@0: 	public final static int	NODEFAULT= 8;
samer@0: 
samer@0: 	public Variable(Node node) { super(node); }
samer@0: 	public Variable(String nm) { this(new Node(nm)); }
samer@0: 	public Variable(String nm, Autocoder m, int flags) { this(nm); init(m,flags); }
samer@0: 
samer@0: 	/** Store this variable's data in the given environment */
samer@0: 	public void save(Environment env) { env.store(node.fullName(), model); }
samer@0: 
samer@0: 	/** Restore this variable's data from the given environment */
samer@0: 	public void load(Environment env) throws Exception {
samer@0: 		env.datum(node.fullName()).get(model);
samer@0: 		changed();
samer@0: 	}
samer@0: 
samer@0: 	public String toString() { return super.toString()+"="+model.string(); }
samer@0: 	
samer@0: 	public void init(Autocoder m, int flags) { model=m; init(flags); }
samer@0: 	public void init(int flags)
samer@0: 	{
samer@0: 		if ((flags&NOINIT)==0)   try { load(Shell.env()); } catch (Exception ex) {} // ??
samer@0: 		if ((flags&REGISTER)!=0) Shell.registerViewable(this);
samer@0: 		// what if no value found at this point?
samer@0: 	}
samer@0: 
samer@0: 	public  Autocoder	getModel()	{ return model; }
samer@0: 	private Autocoder	model;
samer@0: }
samer@0: