243057 - enhancement - ability to assign to Java function result and default properties

Status: RESOLVED FIXED

(Rhino Graveyard :: Compiler, enhancement)

Description

[Mike C.]

User-Agent:       Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0; T312461; YComp 5.0.0.0; .NET CLR 1.1.4322)
Build Identifier: 

This report is a follow up of the newsgroup discussion 
http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&oe=UTF-
8&safe=off&frame=right&th=b21c4e09e133d24c&seekm=409C9F5A.2070208%
40fastmail.fm#link8
and is a new feature request.

In MS JScript you can assign to a construction that looks like a function call, 
for example in ASP:
    Session.Value("foo") = "bar";
which at runtime could be translated by Rhino to
    Session.jsSet_Value("foo", "bar");

The rule is that a property will have n arguments for the getter, and n+1 
arguments for the setter; for the setter, the last argument is rhs.

Also in JScript you can write
    Session("foo") = "bar";
which translates to the same thing, because Value is marked as default property.

A solution to mark getters/setters as default could be to implement a new 
prefix, so the Java class to be scripted will have 
    Session.jsGetDefault_Value(String key)
and
    Session.jsSetDefault_Value(String key, Object val)

When encountering a construct like
    var str = Session("foo")
the runtime could check first if Session is instanceof Callable. If it is not, 
it can continue the introspection with checking whether Session has a default 
getter matching the number of arguments.



Reproducible: Always
Steps to Reproduce:
1. compile Session.Value("foo") = "bar";


Actual Results:  
jsc reports: Invalid assignment left-hand side.


Expected Results:  
Check if the Session object, a Java class provided by the programmer, has a 
setter named jsSet_Value(String key, Object rhs);


Things can get more complicated, for example consider a call to ADODB.Recordset
    var str = rs("field");
that should translate in
    var str = rs.jsGetDefault_Fields().jsGetDefault_Item
("field").jsGetDefault_Value();

Comment 1

[Igor Bukanov]

With the introduction of RefCallable interface Rhino allows to define native
functions that can be used as rvalue so one can define a native function foo so
foo() = bar or even foo() += q works.

As regarding the default option it is already doable throw overriding
Scriptable.get method so I close the bug as fixed.