371033 - Universal support for noSuchMethod

Status: RESOLVED WONTFIX

(Core :: JavaScript Engine, enhancement)

Description

[Igor Bukanov]

Currently __noSuchMethod__ can capture only methods called through obj.notExistingProperty(). It does not work with obj[expression]() or with notExistingName() calls as the following jsshell session demonstrates:

js> o = {}
o = {}
[object Object]
js> o.__noSuchMethod__ = function(id) { print("Unknown call: "+id); } 
o.__noSuchMethod__ = function(id) { print("Unknown call: "+id); } 
function (id) {
    print("Unknown call: " + id);
}
js> o.x()
o.x()
Unknown call: x
js> var name = 'x';
var name = 'x';
js> o[name]()
o[name]()
typein:12: TypeError: o[name] is not a function
js> with (o) { x(); }
with (o) { x(); }
typein:13: ReferenceError: x is not defined

It would nice to extend __noSuchMethod__ support to cover all cases.

Comment 1

[Igor Bukanov]

The new callelem/callname bytecodes that bug 363530 adds should allow to gain all the necessary information to implement this bug.

Comment 2

[Brendan Eich [:brendan]]

We should implement the ES4 catchalls proposal too, not just extend the old nSM hack I did for the Tibet guys.

http://developer.mozilla.org/es4/proposals/catchalls.html (out of date, update coming this week, I'll attach a saved version of the latest wiki page to this bug in the mean time).

/be

Comment 3

[Brendan Eich [:brendan]]

Attachment: hand-exported html version of latest wiki'd proposal

Comment 4

[Igor Bukanov]

I am not working on the bug right now.

Comment 5

[Wilson Lee [:kourge]]

This might, or might not be helpful information:
In SpiderMonkey:

js> var x = { __noSuchMethod__: function(id) { print(id); } }
js> x.y()                                                     
y
js> x["y"]()
y
js> var z = "y"
js> x[z]()
typein:7: TypeError: x[z] is not a function

In Rhino:

js> var x = { __noSuchMethod__: function(id) { print(id); } }
js> x.y()
y
js> x["y"]()
y
js> var z = "y"
js> x[z]()
y

So AFAIK Rhino "does it right" while SpiderMonkey does not.

Comment 6

[Brendan Eich [:brendan]]

Wilson: you are using an out of date SpiderMonkey. Fresh hg.mozilla.org trunk:

js> var x = { __noSuchMethod__: function(id) { print(id); } }
js> x.y()                                                     
y
js> x["y"]()
y
js> var z = "y"
js> x[z]()
y

This bug is somewhat more fixed. Other forms remain unsupporetd, however.

/be

Comment 7

[Wilson Lee [:kourge]]

Oopsies. I just checked and it /is/ fixed on mozilla-central.

Comment 8

[Luke Wagner [:luke]]

If anything, we are going to eventually remove __noSuchMethod__ (bug 683218).