Python declarative

[Chris Angelico]

On Thu, Jan 16, 2014 at 11:48 AM, Tim Chase
<python.list at tim.thechases.com> wrote:
> On 2014-01-16 10:09, Chris Angelico wrote:
>> myWindow = Window(
>>      title="Hello World",
>>      children=[Button(
>>          label="I'm a button",
>>          onClick=exit
>>      )]
>> )
>
> This also solves the problem that **kwargs are just a dict, which is
> inherently unordered.  So with the previous scheme, you'd just get an
> unordered bag of controls that Python could then dump into your
> containing window as its dict-traversal algorithms saw fit. :-)

Yeah, I don't really want my window layout to randomize every Python startup :)

Actually... I'm really REALLY glad code like the previous version
wasn't prevalent. It would have made for intense opposition to hash
randomization - as I recall, the strongest voice against randomization
was that tests would start to fail (IMO, a simple way to print a
dictionary with its keys sorted would both solve that and provide an
aesthetically-pleasing display). Imagine if someone spent hours
crafting child object names in order to force the children to be added
in the right order, and then along comes the new Python and it's all
broken...

But I still think it should be a method (as it is in GTK, not familiar
enough with the others), as there's no way with the parameter system
to (a) add children after object creation, or (b) specify parameters
(GTK's boxes let you choose, per-child, whether they'll be expanded to
fill any spare space - by default they all will, ie spare room is
split between them, but often you want to choose one to be expanded
and another not). PyGTK is mostly there, but since its .add() method
returns None, chaining isn't possible. Method chaining like that is
somewhat controversial... I would love to have some kind of syntax
that says "and the value of this expression is the bit before the
dot", but I have no idea what would be clean.

ChrisA