[Pythoncard-devel] adding attribute types to the component specs

[Kevin A. <al...@se...>]

I'm not real happy with the additional if blocks for displayProperty  
and updateComponent and all the other attribute hacks used to  
interpret and write out resource files.

Ideally, the attribute type would be defined as part of the spec and  
we would query the spec to find out how to handle each property  
rather than having the resourceEditor and propertyEditor make guesses  
based on  a predefined list of attribute names. For example, the  
Button spec (minus comment lines) looks like:

class ButtonSpec(widget.WidgetSpec):
     def __init__(self):
         events = list(ButtonEvents)
         attributes = {
             'label' : { 'presence' : 'optional', 'default':'Button' },
             'default':{'presence':'optional', 'default':0} }
         widget.WidgetSpec.__init__(self, 'Button', 'Widget', events,  
attributes )

This should probably be:

class ButtonSpec(widget.WidgetSpec):
     def __init__(self):
         events = list(ButtonEvents)
         attributes = {
             'label' : { 'type': types.StringType, 'presence' :  
'optional', 'default':'Button' },
             'default':{'type', types.BooleanType,  
'presence':'optional', 'default':False} }
         widget.WidgetSpec.__init__(self, 'Button', 'Widget', events,  
attributes )

Note that 'default' is really a boolean, but when we started  
PythonCard True and False were not available which is why we were  
using 0.

Adding a basic Python type doesn't completely solve the problem  
because you need to know what type of editor to use for a given  
attribute. We could provide an 'editor' item as part of the  
dictionary, but it might more efficient to simply define our own  
types which the property editor would then use to decide which editor  
to be used. For example in addition to types.ListType and  
types.DictionaryType which would use a TextArea for editing we might  
have:

class MultiTextType(types.StringType):
     pass

for 'userdata' and 'text' attributes. We would probably have  
PositionType, SizeType, FontType, ColorType, and other special  
classes to cover a variety of different editors.

Components are supposed to be self-describing and if we're able to  
add enough information to the spec so that the resourceEditor loses  
all special knowledge of the components that would be a big plus.

ka