Hi,
2011/7/14 <[email protected]>:
> Here's a way to do it with a Python dict structure. Given the QML:
> [...]
> you can translate to Python like so:
>
> from QtQuick import Rectangle, parent
> [...]
How would you "import" user-defined (and/or plugin) QML components?
Also, I still can't really see the advantage of using Python syntax to
define QML. Even the dict-based approach doesn't look "natural" to a
Python developer, so a Python developer who would like to "learn" QML
would then have to resort to looking at the documentation for this
custom approach as opposed to the more widely-used (which means more
examples) "real" QML format. You wouldn't want to write a Python
structure that resembles HTML documents, or would you? Think of QML as
a "document format" to declare UIs, which just happens to use
JavaScript for code blocks and expressions. And I think that's the
only block where it would make sense to have Python in QML: Directly
in code blocks and expressions.
Trying to come up with a replacement syntax of QML in Python makes it
harder to learn (less examples), harder to decide (do I want to have
"pure" QML or Python QML?), less stable (Python QML definitely will
take some time to be in a stable, debugged state). Also, who
guarantees that the Python-flavored QML will be supported the same way
that the "original" QML will be? We won't be able to convince people
using C++ now to "try Python" - they would either have to choose to
reuse their existing QML knowledge and assets and ignore PyQML anyway
or learn a new syntax for something they already know to do with a
different syntax (and then the question "What's the point in learning
a new syntax that doesn't give any additional benefits?" comes up
again).
If you have multiple children, your dict-based approach doesn't
guarantee that they appear in the same order as defined (something
that's important for children of the QML Row { } element). You can use
OrderedDict as a workaround, but then again this blows up the syntax
at definition time. Apart from that, the dict-based approach also has
more "syntax noise" (brackets, quotes and colons for the dicts)
compared to the QML version.
How do you pass the implicit "mouse" parameter to your callback of
"onClicked", for accessing the "x" and "y" properties?
In addition to that, QML's expressions are saved as-such and are used
for property bindings. The expression "Rectangle('Rect1').width / 2"
in your code above gets evaluated immediately and the result stored.
Sure, you could try to override some operators, but it won't be
Pythonic and would not be the result one would expect as Python
developer.
Again, I don't say you shouldn't think about such things, I just want
to make it clear that in my opinion, trying to shoehorn the Python
Syntax into QML "just because" might not be a good idea, and anybody's
time could be (in my opinion) better spent improving other parts of
PySide. With that said, I'd like to see an easy way to use/reuse
Python syntax and code in code blocks of QML - which doesn't try to
change the syntax of the markup, but tries to give some value addition
to "normal" QML.
HTH.
Thomas
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