[IronPython] How to reference List objects?

[Michael Foord]

Justin Regele wrote:
> Type Errors where the object is unscriptable means that it does not 
> have any indices intialized.
>
> Use the python interactive interpreter to play around with list 
> methods, and see how they work correctly. This is one of pythons best 
> weapons. if you don't know what objects are in a module, or what 
> attributes/methods are in a class type in dir(<module or classname>) 
> and it will spell it out for you.
>
> you do need to initialize a list before access, however.
> so you CANT do this
>
> x = []
> x[0] = 'something'
>
> you would have to do this(making a list of 10 None objects)
> x = [None] * 10
> x[0] = 'something'
>
> OR use the append() method to make the list more like a dynamic array
>
> x = []
> x.append('something')
>
> this is the python way of doing it, but i'm not sure why you need a 
> .NET list array.

He is creating the list from C# and making it available to Python code. 
As far as I can tell he is doing it right, although maybe the fact that 
his C# book class is private is interfering with it?

Michael


>
> On Mon, Jun 8, 2009 at 11:27 AM, Larry Danberger 
> <larry.danberger at nubium.com <mailto:larry.danberger at nubium.com>> wrote:
>
>     Hi all,
>     I'm new to Python and IronPython, sorry if this is obvious.  I
>     haven't found
>     answer searching web or in IronPython In Action book...
>
>     I have embedded IronPython into silverlight app for scripting,
>     which is
>     working (wow! Btw).  I use scope.SetVariable for dictionaries
>     which works as
>     expected.
>
>     However when passing in a list I am unable to access the objects
>     within a
>     list.
>     For the example below when trying
>     x = books[0].Name
>     I get
>     TypeError: 'List[books]' object is unsubscriptable
>
>     If I do
>     x = books
>     I get back
>     System.Collections.Generic.List'1[testapp.PythonEngine+book]
>
>     If I do
>     Len(books)
>     I get back 4.
>
>     How do I access them individually (by name etc.)?
>
>     My code looks something like this:
>
>     Class book
>     {
>       int ID { get; set; }
>       String Name { get; set; }
>       String Author { get; set; }
>       String Description { get; set; }
>     }
>
>     ...
>     List<book> _books = new List<book>();
>
>     _books.Add(new book { ID=1, Name="book1", Author="author1",
>     Description="Description1"});
>     _books.Add(new book { ID=2, Name="book2", Author="author2",
>     Description="Description2"});
>     _books.Add(new book { ID=3, Name="book3", Author="author3",
>     Description="Description3"});
>     _books.Add(new book { ID=4, Name="book4", Author="author4",
>     Description="Description4"});
>
>     ...
>     _scope.SetVariable("books", _books);
>
>
>     Any help appreciated, thanks!
>     -Larry
>
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