208211 - Implement object call semantics for IDispatch objects: obj(x) for obj.item(x)

Status: RESOLVED INVALID

(Core :: XPConnect, enhancement)

Description

[David Bradley]

Microsoft provides some syntatic sugar that allows callers to make a call on a
object. For instance,

if objA had a method foo. And it was considered the default method.

objA("test"); would invoke foo on objA passing test. foo could also be a
property, this often occurs when the object represent a collection of items.
Rather than explicitly saying objA.items(x), MS allows the shorthand objA(x);

Comment 1

[Brendan Eich [:brendan]]

See http://lxr.mozilla.org/mozilla/source/js/src/js.c#1604 for an example of how
to use JS_SetCallReturnValue2 in conjunction with returning an object (typically
the |this| parameter, canonically named |obj| in native JS functions), to return
a reference type (obj, id) where id is |argv[0]|.  Such a return type is handled
by getting the value of that property, when the call occurs in an "rvalue"
content; else by setting that reference to a value when the call occurs on the
left-hand side of an assignment operator.

/be

Comment 2

[David Bradley]

I finally found an example/description in MSDN:

The Fields collection is the default member of the Recordset object. As a
result, the following two code statements are equivalent.

Debug.Print objRs.Fields.Item(0)  ' Both statements print 
Debug.Print objRs(0)              '  the Value of Item(0).

Comment 3

[David Bradley]

From what I can tell, the key is the dispid which is zero. I've checked several
cases, and this seems to be the common factor, so that's easy enough to check for.

Comment 4

[David Bradley]

Moving out, speak up if you believe this needs to be considered for 1.5b

Comment 5

[David Bradley]

Moving out

Comment 6

[Ed Morley [:emorley]]

The IDispatch API was removed in bug 662000.

-> INVALID

[Filter bugspam on idispatchinvalid]