Problems translating map file layers to mapscript

[Sean Gillies]

On Oct 18, 2005, at 8:30 PM, David Niergarth wrote:

> 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
>

You're welcome, David, I hope you haven't been struggling too long with 
this problem.

Sean

--
Sean Gillies
sgillies at frii dot com
http://zcologia.com