Toga: A Python native, OS native GUI toolkit | Better HN

69 comments

52 comments · 13 top-level

WoodenChair11y ago· 3 in thread

This project appears to be quite early stage (many missing APIs, no stable Windows support, poor documentation, etc) but very promising. If it had integration with a GUI designer and was feature complete, I'd start using it on projects.

I've explored the options for Python GUI toolkits quite extensively. They're a real challenge to get running conveniently (by conveniently, I mean a simple PIP install away with no external C/C++ library dependencies) on OS X with native looks, and that is a nice advantage of this one IMHO.

freakboy374211y ago

Thanks for the kind words.

Yes, the project is very early stage - I've been tinkering for 6 months in my spare time (and it's not like I had a whole lot of that to start with). Getting cross platform on 4 platforms has, as you might expect, taken a bit of effort.

I started down this path because the existing options didn't satisfy me. When my initial couple of weeks of tinkering proved that it was possible to get widgets without binary dependencies, that gave me the momentum to get to the point that I've publicly announced. There's plenty left to do, but I've got high hopes.

andreasvc11y ago

"No external C/C++ library dependencies" is simply impossible. Given that the host OS is not implemented in Python, some kind of bridge to its native libraries is necessary for a GUI library. Such libraries can be either compiled during the pip installation, or required as an external dependency installed using the package manager of the OS, Either way it's never going to be hassle free due to all the different OSes and package managers.

TazeTSchnitzel11y ago

>"No external C/C++ library dependencies" is simply impossible. Given that the host OS is not implemented in Python, some kind of bridge to its native libraries is necessary for a GUI library.

Not true. Python provides facilities for dealing with dynamic link libraries from native Python code. These can be used to interface with the OS directly, without necessitating writing a C/C++ wrapper.

malkia11y ago· 2 in thread

Another toolkit that uses Python, but with Qt (and previously also wxWidgets) is enaml - it has a cassowary solver, a Visual Studio docking system, and very interesting approach to connecting that to visual elements.

https://github.com/nucleic/enaml

http://nucleic.github.io/enaml/docs/

drglitch11y ago

Having developed several advanced apps in enaml over last 2 years, i commend enaml. It encourages MVC and provides clean observer-style bindings (Atom).

The framework is used internally by at least one fortune 50 corp for a large app suite.

freakboy374211y ago

Project author here; Thanks for the heads up - I haven't come across Enaml before. I'll take a look.

Camillo11y ago· 6 in thread

The Mac screenshot I see on the home page looks about as non-native as the average Qt app.

ColinCera11y ago

It's using native Cocoa controls, so I'm not sure why you don't think it looks native.

i_am_ralpht11y ago

Because the layout that's presented is not native. Actual mac apps don't have tabs and toolbars pushed together like that, and the margins are different.

wxWidgets can use the platform native controls, but the apps rarely look native because the layouts and behaviors are non-native. Mac/GNOME/Windows all have different ideal metrics for spacings, control placement and labeling (OK/Cancel vs Cancel/"Do Thing") -- being native means getting all of those details correct.

WoodenChair11y ago

That's a matter of design, not an observation based on technical merits.

ZenoArrow11y ago

Maybe I'm missing something, but isn't the main 'hook' for this library that it looks native? Looks like it uses GTK+, so from a technical standpoint it would be as "native" as Qt.

Derbasti11y ago

There are probably quite a few Qt apps you haven't noticed because they look perfectly native. What you mean is "a badly designed Qt app".

aroman11y ago

i highly, highly doubt that, but i'd love to be proven wrong. what's the best example of an OS X-native-looking Qt app you know of?

rkangel11y ago· 3 in thread

For a project like this where there are many other potential options (wxPython etc.) the first question I'm thinking is 'why do I care about this new one'. I.e. What does this do better/differently/more conveniently. I assume the answer here us the native Python aspect and not needing big compiled libraries. Might be worth selling it a bit more on your homepage and making that advantage clearer?

It may be that everyone else picked up on Python native quicker than I did, I'm reading this in bed during a lie in so am a bit sleepy!

freakboy374211y ago

Thanks for the feedback! I cover some of the "why" in the docs, but I agree the homepage could do a better job of making the case for a new UI toolkit.

The short version:

* System native widgets, not themes

* Installable via "pip install" - no third party or binary dependencies

* Not just naïve wrappers around widgets - capture the underlying use case and provide an API wrapper.

* Genuinely Python native. This means exploiting language specific features (like generators and context managers)

_random_11y ago

"Python native" is an oxymoron, given the language's interpreted nature. "Python-idiomatic" would probably be a more correct choice of words. But that's just me.

Shorel11y ago

wxPython has system native widgets in every platform. wxWidgets has system native widgets in every platform, and it is the only one I know that provides that.

May be you are thinking about some other toolkit that's not wxWidgets.

atanasb11y ago· 1 in thread

This looks promising. It would be better if the documentation was a bit more exhaustive[0]

[0]http://toga.readthedocs.org/en/latest/internals/platforms/de....

freakboy374211y ago

I'll completely agree. This is a project that has been built in the last 6 months of my spare time from all my other projects, and most of that time has been spent getting things to a point where they work. The APIs aren't yet stable enough to warrant me spending a bunch of time formalising them, but I absolutely want to document them as soon as the ground stops moving :-)

rjn94511y ago· 6 in thread

I was really confused when I read "the constrain() call takes expressions that define the relationships you want to impose" (emphasis mine) and saw this code:

  container.constrain(button.TOP == container.TOP + 50)

Python doesn't let you pass expressions! Why isn't that just getting evaluated to true or false? Is this not vanilla Python? Is there a pre-processor?

I dove into the code and found the answer here[1]. button.TOP and container.TOP are both Toga Attributes, which have their equality operators redefined.

Very interesting and clever use of operator overloading.

[1] https://github.com/pybee/toga/blob/master/toga/constraint.py

rkangel11y ago

I am very conflicted about that trick. On the one hand it is a neat bit of syntax to express what you want, but it goes completely against your expectations of how Python syntax is parsed. 'Clever use of operator overloading' historically has always meant 'confusing use of operator overloading' - something the C++ community took some time to learn.

Python is very good at behaving as you expect it to, despite the fact that you can implement pretty much any magic. This is down to library design more than it is language design.

TheLoneWolfling11y ago

At least it's less magic than puLP:

  prob += x*2 + y, "foo"

This sets the objective function of prob to (2x+y), and assigns it a name of "foo".

  prob += x*2 + y > 3, "abcd"

That puts a constraint that 2x + y > 3, called "abcd".

On both of these the string is optional.

I'm also conflicted. On one hand, it's about the most compact syntax you can get for something like this - when similar libraries in languages without operator overloading resort to passing strings into functions... On the other hand, it can be utterly incomprehensible if you haven't gone through the documentation.

bsimpson11y ago

FWIW, I've seen the double-equals syntax in GSS as well. It's a common idiom in the constraint programming community; it's supposed to symbolize that the two sides change in sync -- container.TOP can change button.TOP or vice-versa.

I see your argument about overloaded operators being dangerous for newcomers, but the syntax isn't completely fabricated.

freakboy374211y ago

Thanks for the compliment. As others have pointed out, this isn't an idea of my own creation - others (e.g., SQLAlchemy) have taken similar approaches in other APIs. I'm just exploiting a pattern that I've seen used to good effect elsewhere.

0x006A11y ago

some ORMs do operator overloading too, i.e. SQLAlchemy http://docs.sqlalchemy.org/en/rel_0_9/core/sqlelement.html

abritishguy11y ago

Google use operator overloading in their appengine stuff.

davidjhall11y ago· 3 in thread

  left_container = toga.OptionContainer()
  AttributeError: 'module' object has no attribute 'OptionContainer'

Frustrating when things that are supposed to work out of the box, don't. Initial search yields no help.

freakboy374211y ago

Sounds like you're on Windows. Unfortunately, Windows support is pretty primitive at this point (reflecting my own priorities - OSX, Unix and mobile support is a more pressing concern). I'll update the homepage and docs to better reflect the current project status.

Longer term, I definitely want to support Windows to the same level as other platforms; any assistance on this front would be gratefully accepted.

a_bonobo11y ago

What version of toga are you running? I'm on Ubuntu with Python 2.7.6, toga v 0.1.0 and cassowary 0.5 and your oneliner works fine.

Edit: In fact, OptionContainer is just 15 days old, so I think you've got an old version: https://github.com/pybee/toga/commit/262efbfc00fae0a96e09666...

Lord_DeathMatch11y ago

either than or you're on windows, where unfortunately next to nothing is implemented

allegory11y ago· 1 in thread

Very interesting. They have other tools which are rather useful looking as well: http://pybee.org/ (debugger, test runner, coverage visualiser etc)

freakboy374211y ago

Thanks for the promotion :-)

Of those tools, the test runner (cricket) is the most mature; the debugger isn't much more than a proof of concept. Those tools are also based in Tkinter at the moment; I started Toga because I've started to hit the limits of Tkinter.

The intention is to port the other PyBee tools to Toga as soon as they get mature enough.

roryokane11y ago· 3 in thread

Does anyone know of any similar GUI toolkits, for languages other than Python? That is, cross-platform GUI toolkits that use true OS-native widgets, and ideally, also abstract away platform-specific details such as the placement of the Quit/Exit menu items and the order of OK/Cancel buttons. Toga is actually the first library with those features that I’ve heard of.

ANTSANTS11y ago

I think you're looking for phoenix: http://byuu.org/programming/phoenix/

An example application using it, with the GTK backend: https://i.imgur.com/pW2Jl9q.png

and the Qt backend: https://i.imgur.com/z6cC3rM.png

The author (byuu) posts here, he might be able to answer questions.

scythe11y ago

The most famous such library is wxWidgets; it supports "Python, Perl, Ruby, and many other languages":

http://www.wxwidgets.org

Shorel11y ago

wxWidgets has been doing that for more than a decade.

Well, may be some very platform specific guidelines have to be added by hand, but the actual widgets used are native.

calpaterson11y ago· 7 in thread

The use of constraints to let the user specify where to put things but still allow enough flexibility to do OS-dependant things is interesting (and possibly novel?):

http://toga.readthedocs.org/en/latest/introduction/tutorial-...

daurnimator11y ago

Cassowary ( http://constraints.cs.washington.edu/cassowary/ ) is used by Apple for this.

freakboy374211y ago

FYI, Toga uses Cassowary as well - natively through Apple's implementation on OSX and iOS, and via a Python implementation of the algorithm (http://pybee.org/cassowary/) for GTK and Windows.

PuercoPop11y ago

Not really novel[1], just not used enough

[1]: https://en.wikipedia.org/wiki/Sketchpad

Game_Ender11y ago

It's similar to the sizer concept in wxWidgets:

http://wiki.wxwidgets.org/WxSizer

matthewmacleod11y ago

I think that's basically the same as Cocoa's Autolayout, which is also constraint-based. It's a good model, though.

james2vegas11y ago

yeah, very novel.

https://developer.mozilla.org/en-US/docs/Mozilla/Tech/XUL/Tu...

http://docs.oracle.com/javase/tutorial/uiswing/layout/howLay...

comex11y ago

Neither of those are constraint based.

ymeshesha11y ago

This toolkit seems extremely simple and user-friendly, might have to give it a try

theophrastus11y ago· 2 in thread

loutish/lazy Debian/"testing" system here:

   ~> apt-cache search toga
   toga2 - computer chess engine, calculates chess moves

(hm... wake me when it hits testing)

freakboy374211y ago

Given that the project was announced publicly 1 week ago, I wouldn't expect to see it in Debian (testing or otherwise) for a little while.

andreasvc11y ago

As a Python library, the package would be called python-toga.

analog3111y ago· 2 in thread

Android compatible?

freakboy374211y ago

Not yet. Android support is on the todo list once I've processed all the feedback that has come as a result of the initial release.

JasonFruit11y ago

They say it would be nice, but not yet, no.

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