Win32 COM and Collections

[Alex Martelli]

"Dale Strickland-Clark" <dale at out-think.NOSPAMco.uk> wrote in message
news:yPaq5.24731$Xg.672226 at news-east.usenetserver.com...
    [snip]
I've already answered Dave by e-mail, but, for the record:

with this version of CollectionTest, in his otherwise unchanged
code:

     def CollectionTest(self):
         data = ['a', 'b', 'c']
         cln = win32com.server.util.NewCollection(data)
         return cln

the following VBScript code:

Set Testing = CreateObject("Testing.Collection")
WScript.echo(Testing.Test())

Set collect = Testing.CollectionTest()
WScript.echo(CStr(collect.Count()) & " items in collection")

For Each element In collect
    WScript.echo(element)
Next

will happily run under, e.g., CScript, and output:
The Testing Collection COM server is running.
3 items in collection
a
b
c


To return a collection of _objects_, they need a modicum
of COM support, e.g.:

class ClnTest:
    _public_methods_ = ['Helo']
    def __init__(self, data):
        self.val = data
    def Helo(self):
        return 'Here is ('+self.val+')'

and, with the line, at the start of the Python script:

from win32com.server.util import NewCollection, wrap

changing CollectionTest to:

    def CollectionTest(self):
        data = [wrap(ClnTest('a')), wrap(ClnTest('b')), wrap(ClnTest('c'))]
        # data = ['a', 'b', 'c']
        cln = NewCollection(data)
        return cln

and the VBS line in the foreach loop to:
    WScript.echo(element.Helo())

we similarly get:
The Testing Collection COM server is running.
3 items in collection
Here is (a)
Here is (b)
Here is (c)


Note: the _public_methods_ member IS needed in the class;
without it, you'll get something such as:

The Testing Collection COM server is running.
C:\My Documents\testob.vbs(4, 1) Python COM Server Internal Error:
Unexpected Py
thon Error: win32com.server.policy error: Object does not support
DesignatedWrap
Policy

The 'wrap' (win32com.server.util.wrap) is also necessary for the
objects placed in the list passed to the NewCollection function;
without it, you'll get something such as:

The Testing Collection COM server is running.
3 items in collection
C:\My Documents\testob.vbs(7, 1) Unspecified error



Alex