I am currently working with python and Qt which is kind of new for me coming from the C++ version and I realised that in the oficial documentation it says that an UI file can be loaded both from .ui or creating a python class and transforming the file into .py file.
I get the benefits of using .ui it is dynamically loaded so no need to transform it into python file with every change but what are the benefits of doing that?, Do you get any improvements in run time? Is it something else?
Thanks
Well, this question is dangerously near to the "Opinion-based" flag, but it's also a common one and I believe it deserves at least a partial answer.
Conceptually, both using the pyuic approach and the uic.loadUi() method are the same and behave in very similar ways, but with some slight differencies.
To better explain all this, I'll use the documentation about using Designer as a reference.
pyuic approach, or the "python object" method
This is probably the most popular method, especially amongst beginners. What it does is to create a python object that is used to create the ui and, if used following the "single inheritance" approach, it also behaves as an "interface" to the ui itself, since the ui object its instance creates has all widgets available as its attributes: if you create a push button, it will be available as ui.pushButton, the first label will be ui.label and so on.
In the first example of the documentation linked above, that ui object is stand-alone; that's a very basic example (I believe it was given just to demonstrate its usage, since it wouldn't provide a lot of interaction besides the connections created within Designer) and is not very useful, but it's very similar to the single inheritance method: the button would be self.ui.pushButton, etc.
IF the "multiple inheritance" method is used, the ui object will coincide with the widget subclass. In that case, the button will be self.pushButton, the label self.label, etc.
This is very important from the python point of view, because it means that those attribute names will overwrite any other instance attribute that will use the same name: if you have a function named "saveFile" and you name the button "saveFile", you won't have any [direct] access to that instance method any more as soon as setupUi is returned. In this case, using the single inheritance method might be helpful - but, in reality, you could just be more careful about function and object names.
Finally, if you don't know what the pyuic generated file does and what's it for, you might be inclined to use it to create your program. That is wrong for a lot of reasons, but, most importantly, because you might certainly realize at some point that you have to edit your ui, and merging the new changes with your modified code is clearly a PITA you don't want to face.
I recently answered a related question, trying to explain what happens when setupUi() is called in much more depth.
Using uic.loadUi
I'd say that this is a more "modular" approach, mostly because it's much more direct: as already pointed out in the question, you don't have to constantly regenerate the ui files each time they're modified.
But, there's a catch.
First of all: obviously the loading, parsing and building of an UI from an XML file is not as fast as creating the ui directly from code (which is exactly what the pyuic file does within setupUi()).
Then, there is at least one relatively small bug about layout contents margins: when using loadUi, the default system/form margins might be completely ignored and set to 0 if not explicitly set. There is a workaround about that, explained in Size of verticalLayout is different in Qt Designer and PyQt program (thanks to eyllanesc).
A comparison
pyuic approach
Pros:
it's faster; in a very simple test with a hundred buttons and a tablewidget with more than 1200 items I measured the following bests:
pyuic loading: 33.2ms
loadUi loading: 51.8ms
this ratio is obviously not linear for a multitude of reasons, but you can get the idea
if used with the single inheritance method, it can prevent accidental instance attribute overwritings, and it also means a more "contained" object structure
using python imports ensures a more coherent project structure, especially in the deployment process (having non-python files is a common source of problems)
the contents of those files are actually instructive, especially for beginners
Cons:
you always must remember to regenerate the python files everytime you update an ui; we all know how easy is to forget an apparently meaningless step like this might be, expecially after hours of coding: I've seen plenty of situations for which people was banging heads on desks (hopefully both theirs) for hours because of untraceable issues, before realizing that they just forgot to run pyuic or didn't run it on the right files; my own forehead still hurts ;-)
file tracking: you have to count two files for each ui, and you might forget one of them along the way when migrating/forking/etc, and if you forgot an ui file it possibly means that you have to recreate it completely from scratch
n00b alert: beginners are commonly led to think that the generated python file is the one to be used to create their programs, which is obviously wrong; unfortunately, the # WARNING! message is not clear enough (I've been almost begging the head PyQt developer about this); while this is obviously not an actual problem of this approach, right now it results in being so
some of the contents of a pyuic generated files are usually unnecessary (most importantly, the object name, which is used only for specific cases), and that's pretty obvious, since it's automatically generated ("you might need that, so better safe than sorry"); also, related to the issue above, people might be led to think that everything pyuic creates is actually needed for a GUI, resulting in unnecessary code that decreases its readability
loadUi method
Pros:
it's direct and immediate: you edit your ui on Designer, you save it (or, at least, you remember to do it...), and when you run your code it's already there; no fuss, no muss, and desks/foreheads are safe(r)
file tracking and deployment: it's just one file per ui, you can put all those ui files in a separate folder, you don't have to do anything else and you don't risk to forget something on the way
direct access to widgets (but this can be achieved using the multiple inheritance approach also)
Cons:
the layout issue mentioned above
possible instance attribute overwriting and no "ui" object "containment"
slightly slower loading
path and deployment: loading is done using os relative paths and system separators, so if you put the ui in a directory different from the py file that loads that .ui you'll have to consider that; also, some package managers use to compress everything, resulting in access errors unless paths are correctly managed
In my opinion, all considering, the loadUi method is usually the better choice. It doesn't distract me, it allows better conceptual compartmentation (which is usually good and also follows a pattern similar to MVC much more closely, conceptually speaking) and I strongly believe it as being far less prone to programmer errors, for a multitude of reasons.
But that's clearly a matter of choice.
We should also and always remember that, like every other choice we do, using ui files is an option.
There is people who completely avoids them (as there is people who uses them literally for anything), but, like everything, it all and always depends on the context.
A big benefit of using pyuic is that code autocompletion will work.
This can make programming much easier and faster.
Then there's the fact that everything loads faster.
pyuic6-Tool can be used to automate the call of pyuic6 when the application is run and only convert .ui files when they change.
It's a little bit longer to set up than just using uic.loadUi but the autocompletion is well worth it if you use something like PyCharm.
I'm working in a tool that is supposed to generate some Java Code to accelerate part of the development based in a swing input dialog...there is no need to get any further with it so I'm going to my problem...
I need to retrieve all the attributes from a class to check whenever it is necessary to add a new one. I tried to use reflection but things started getting complicated. In order to use reflection I need to compile the class I want to get the attributes as it does not work directly from .java file, .class is required for it.
The problem is that many of the classes has a lot of dependencies! Due to some design flaws some classes are a high coupled, so if I am supposed to dynamic use a class loader to compile a class A I would have to retrieve and compile all its dependencies! And then retrieve all the possible dependencies from the class A dependency classes!
I made a test running an existing ant file to compile to whole project instead of the above approach but it takes about 9 minutes to finish! From the final user perspective waiting 9 minutes every run is not accetable!
Does any one here knows a better solution???
If you want to avoid working with reflection and bytecode, it means that you will have to parse the .java files yourself with a grammar and, well, a parser based on this grammar. It is possible (especially if you do not implement the whole grammar, because many java features might be useless in your project perimeter), but I reckon this is no easy task.
There is an Apache commons Sandbox package called ClassScan. It is capable of doing the kind of source parsing you appear to require. http://commons.apache.org/sandbox/commons-classscan/. Note that it is in the Sandbox, so not part of the Commons Proper.
is there a simple way to generate a JAR file, that contains only the classes that depend transitive from a certain "main" class (reflection omitted of course).
I want to provide a little part of my application to someone else but do not want to export the whole application.
Thanks,
M.
Probably the easiest approach is using a tool like yGuard which "...provides elaborate code shrinking functionality through dependency analysis." This would also solve the same problem where you give it an entry point, and it performs dependency analysis to work out which classes can be excluded from the Jar.
However, I have throught about this problem myself a few times and fancied having a go at it myself for the challenge. All it would take would be to parse the import statements of Java source files and build a dependncy graph of how the classes interact with each other. Each reference from the main class should be recursively scanned until a complete graph is assembled. Then once the graph is assembled it would be a case of outputting this in a way that some packaging logic could process (or if you are feeling daring, the JDK has its own built in Jar creating/modifying code to do it yourself). Granted, this approach would require writing this custom utility and would also miss fully qualified class references in the code.
We are working on a project where we have multiple modules- all these share a common set of functions like rounding, string parsing etc.
Currently, we have added these functions into the parent container (which calls these modules) and use them in the respective modules. Likewise, if we have to share variables between modules, we add them to the parent module- so it becomes shareable across.
Is this the right approach- both from a performance and structure perspective?
You should create a runtime shared library project (RSL) and have some classes with static functions. That is how we do it. This can be shared between all of the modules, also you can then use that RSL for any future projects as well.
Maybe you are looking about Singletons.
Check my answer here please : use actionscript file in flex library
I have a program consisting of multiple SWF's. An AS2-SWF loads a bunch of AS1-SWFs.
It's a crappy program. I'd like to specify the GUI in MXML and perhaps refactor some code to AS3. However, converting all of the 300+ symbols to AS3 or whatever is undoable.
What are my options in converting to AS3/Flex/MXML? The app is very simple, only also quite large. It consists only of buttons, backgrounds and attention-texts. All the button texts are in XML files.
I want to turn this into pretty code ASAP but also controlled so the code becomes:
easily updateable/maintainable,
readable
learnable (so I can have the updating done by someone that can only script AS3 or even MXML).
Of course doing this is on my own initiative, if it'll take more than a week, I won't be able to find the time.
Regards, Jurgen
This might help:
http://flexman.info/2009/03/29/as3converter-an-ant-task-small-collection-of-as3/
It's mainly for AS2 code, so FLA editing is out of the question. But you should certainly look into JSFL.
There are some pretty good scripts out there already dealing with something like this:
http://bumpslide.com/blog/2009/03/07/jsfl-class-generator/
What this command does is that it
looks through your library and finds
all library items that have a custom
linkage class name. If the class
extends flash.display.MovieClip (or if
the base class is blank), it checks to
see if a classfile exists, and if not,
it creates it for you. When it does
this, the script looks at all the
items on the timeline and adds
relevant properties to your class. If
these clips are instances of other
components, they will be typed as
such, and relevant import statements
will automatically be added to your
class. If your component is set to
extend some other class (for instance,
com.bumpslide.ui.Button), no class
will be generated. Class files will be
written to the correct package
location inside the first custom class
path defined in your publish settings.
Jurgen, I feel for you... it sounds like a lot of work.
What sorts of issues do you have? are all the swfs treatable as different classes? is there much overlap in the logic or does each object have a specific role?
I think having so many different SWFs may possibly lead to scoping problems> which swf talks to which. you may be able to set up something with as3 that uses the existing parts and then try making a facade over the existing code > use the existing logic in the swfs and do the visual part through mxml. other than that, all I can advise is a rebuild. you might find yourself in need of a swf decompiler too if you are missing some of the original fla's