Problems translating map file layers to mapscript

[David Niergarth]

Hi Sean,

> I suspect that you might be doing something like this:
> 
>     class.label = mapscript.labelObj()
> 
> right? This could be your problem.

Yes, that's exactly it.

> Instances of mapscript.classObj are **complete**. There is no need to 
> create new attributes for them. A new instance of classObj already has a 
> properly initialized labelObj as a "label" attribute. New instances of 
> labelObj (as above) won't be properly initialized. That's just the way 
> MapServer/mapscript is. Underneath the Python wrapper is a lot of C code 
> which still presumes that we're parsing a mapfile.

Ok, I see now how it works now.

> Here's an example session:
> 
> Python 2.3 (#1, Sep 13 2003, 00:49:11)
> [GCC 3.3 20030304 (Apple Computer, Inc. build 1495)] on darwin
> Type "help", "copyright", "credits" or "license" for more information.
>  >>> import mapscript
>  >>> c = mapscript.classObj()
>  >>> c.label.minsize
> 4
>  >>> c.label.maxsize
> 256
> 
> those are the normal defaults, and will give you working labels. Now, 
> the problematic usage:
> 
>  >>> l = mapscript.labelObj()
>  >>> l.minsize
> 0
>  >>> l.maxsize
> 0
>  >>>
> 
> this label is going to fail.

You have x-ray vision, I see! ;)

> Rule of thumb: whenever an object has another object attribute with a 
> single value (such as the label attribute of a classObj), that attribute 
> will be created and initialize by the parent's constructor.

Thanks for your help,

--David