There are no examples online and I cannot seem to understand how to properly implement task.IDelayedCall.
For example, it requires an interface input, what would a simple code look like with its implementation with a delay on the call and a cancel sometime later?
For example, when I try:
from zope.interface import Interface
clock=IDelayedCall(Interface)
This brings up an error:
'Could not adapt',InterfaceClass zope.interface.Interface>, <InterfaceClass twisted.internet.interfaces.IDelayedCall
Related
I’d like to define a test assertions myself, i.e. not just use the predefined (test-->> …) etc combinators, and I wonder how to register the test result (success, or failure with a string) with the test driver.
Looking at their code I see that (inc-failures), (inc-successes) and (eprintf), but if I try to use them myself, I get
inc-successes: unbound identifier
How can I get hold of this? Or is this not possible, because it’s defined in private/reduction-semantics.rkt, but not provided from that file? If it it is not possible, what is the best practice for implementing new test combinators?
I'm trying to learn PyQt5 and I am finding it very difficult since I can't just guess what methods are available. I've just spent an entire week trying to find a method to simulate a button push. I eventually found the solution ( QPushButton.animateClick() ) only after stumbling across an example someone left out there (how did this person know this?). It's very difficult to develop without some reference to what's available for tools!
Riverbank has a version of what I'm looking for but it is not complete making it virtually useless.
pyqt5 being a qt5 binding has almost all the functionalities (there are minimal known incompatibilities) so the qt5 documentation: https://doc.qt.io/ is valid for pyqt5 except for small exceptions.
Although the target of the documentation is c++ the description of the classes and methods are generic, so they also validly apply for pyqt5, on the other hand many of the examples are written in c++ but the translation to python in many cases is trivial .
So to avoid doing a double task it seems that Riverbank Computing Limited only documents the exceptions indicated in the pyqt5 docs: https://www.riverbankcomputing.com/static/Docs/PyQt5/
The next part of my answer will propose tips to handle the Qt documentation.
The Qt documentation also has an easy to understand structure, for example let's analyze the QPushButton class (https://doc.qt.io/qt-5/qpushbutton.html):
At the top there is a table:
This table indicates how to include the class in a C++ project, how to add it to qmake, from which class it inherits, and which classes inherit from it. From the above, relevant information for PyQt5 can be extracted, such as to which sub-module the class belongs to: In this case we use QT += widgets that inform us that it belongs to the QtWidgets sub-module, in general if Qt += submodulefoo belongs to QtSubModuleFoo (camelcase)
If you want to know all the methods of the QPushButton class, you must use the "List of all members, including inherited members" link below the table, in this case the link will be https://doc.qt.io/qt-5/qpushbutton-members.html where is the complete list of all class methods, enumerations, etc.
Other tips to understand the conversion between Qt/C++ and PyQt5/Python are:
Some methods use pointers to receive information such as:
void QLayout::getContentsMargins(int *left, int *top, int *right, int *bottom) const
bool QProcess::startDetached(qint64 *pid = nullptr), etc
those transformed to PyQt5 as:
lay = QtWidgets.QXLayout()
left, top, right, bottom = lay.getContentsMargins()
process = QProcess()
# ...
ok, pid = process.startDetached()
Some methods collide with reserved words such as exec , raise, print, etc so to avoid incompatibilities, the underscore is added at the end: exec_, raise_, print_, etc
In Qt, the Q_SLOT and Q_SIGNAL that are translated into python are used through the #pyqtSlot and #pyqtSignal decorators.
In conclusion, my recommendation is that you use the Qt and PyQt5 documentation at the same time to know all the functionalities, in addition there are many Q&A in SO about translations from one language to another so you could learn from there.
The Qt documentation can also be consulted using the Qt Assistant tool.
The main PyQt5 documentation is on the official website:
https://www.riverbankcomputing.com/static/Docs/PyQt5/
But it's still incomplete, and most parts refer to the official Qt documentation:
https://doc.qt.io/qt-5/
While that's C++ oriented, consider that almost every module, class and function behave exactly in the same way as it does in python, so it's usually better to use that.
Consider that:
in the function lists you'll always see the returned type on the left of each function;
"void" means that the function returns None;
when overriding some existing method (expecially private and virtual), you always have to return the expected types listed for that function;
function arguments are usually written in the form [const] Type argName=default: you can usually ignore the "const" part (it's a C++ term), while the argName for keyword arguments might be different in PyQt;
some functions could have different names, since they're reserved on python (print, raise, etc); in those cases, an underscore is always appended;
some positional or keyword arguments might be different, or the return type signature might; that's because in C++ you can use a pointer to a variable as an argument, and the function will change that variable using the pointer (this is an oversimplification);
all "properties" are not python properties, and they are only accessible through their parenthesis functions, such as self.width() an self.setWidth();
some methods have different overrides, in some cases python has special cases with different arguments that are not available in C++, and viceversa; also, some methods don't exist at all in one case or the other;
My suggestion is to always use the official documentation, it's only a matter of habit to get used to the C++ references (and you'll see that it is educational too); whenever some doubt raises, check the PyQt documentation to see what's different and use the help command in the python shell.
I want to make my custom inline function in .kt file using checkRadix function already implemented by Kotlin.
But I cannot import it. How can I import and use it?
I tried
import kotlin.jvm.JvmMultifileClass.*
kotlin.jvm.JvmMultifileClass.checkRadix(radix)
But I can't compile and there is no recommended resolution by IDE.
That function is marked as internal, which means it's only available within that module — i.e. within the Kotlin stdlib, not to your code.
I don't know why it's marked like that; maybe JetBrains consider it an implementation detail. But they clearly don't want it being used by any other code.
(Of course, it wouldn't be hard to reimplement yourself.)
I am working on a VB.NET project which requires the extensive used of Unit Tests but am having problems mocking on of the classes.
Here is a breakdown of the issue:
Using NUnit and Rhino Mock 3.6
VS2010 & VB.NET
I have an interface which contains a number of methods and an Event.
The class which implements that Interface raises the event when one of the methods is called.
When I mock the object in my tests I can stub methods and create/assert expectations on the methods with no problems.
How do I configure the mock object so that when a method is called the event is raised so that I can assert that is was raised?
I have found numerous posts using C# which suggest code like this
mockObject.MyEvent += null...
When I try this 'MyEvent' does not appear in Intellisense.
I'm obviously not configuring my test/mock correctly but with so few VB.NET examples out there I'm drawing a blank.
Sorry for my lack of VB syntax; I'm a C# guy. Also, I think you should be congratulated for writing tests at all, regardless of test first or test last.
I think your code needs refactoring. It sounds like you have an interface that requires implementations to contain an event, and then another class (which you're testing) depends on this interface. The code under test then executes the event when certain things happen.
The question in my mind is, "Why is it a publically exposed event?" Why not just a method that implementations can define? I suppose the event could have multiple delegates being added to it dynamically somewhere, but if that's something you really need, then the implementation should figure out how that works. You could replace the event with a pair of methods: HandleEvent([event parameters]) and AddEventListener(TheDelegateType listener). I think the meaning and usage of those should be obvious enough. If the implementation wants to use events internally, it can, but I feel like that's an implementation detail that users of the interface should not care about. All they should care about is adding their listener and that all the listeners get called. Then you can just assert that HandleEvent or AddEventListener were called. This is probably the simplest way to make this more testable.
If you really need to keep the event, then see here for information on mocking delegates. My advice would be to mock a delegate, add it to the event during set up, and then assert it was called. This might also be useful if you need to test that things are added to the event.
Also, I wouldn't rely on Intellisense too much. Mocking is done via some crafty IL code, I believe. I wouldn't count on Intellisense to keep up with members of its objects, especially when you start getting beyond normal methods.
Is something like this possible? If so, could you point me in the right direction for learning how?
applicationx tries to run the method start() in dll_one.dll
dll_one.dll runs the command
applicationx tries to run the method run() in dll_one.dll
dll_one.dll doesn't have a method run() and hasn't prepared for such an occurance.
dll_one.dll asks dll_two.dll if it has a run()
dll_two runs run()
Basically, I want it so if dllA doesn't have a method that the application is looking for, it asks dllB. This is assuming, as well, that ApplicationX and dllB don't know anything about dllA and dllA kind of just appeared out of nowhere (I want dlls dynamically like a patch to my applications without having to rewrite ALL of the methods, properties, etc. in the dll and have everything else just routed to the old dll).
Any ideas? Keep in mind, I'm using vb.net so a .net reference is appreciated.
It seems like you're asking for a plug-in architecture for your app (except that "patch" part is bothering me). If so, you can try MEF, which solves this exact problem.
The specific thing you ask for isn't possible. You can't have a non-existent method call automatically re-routed to a different dll. You can't "run the method run() in dll_one.dll" unless you've compiled that code, and it won't compile if the method doesn't exist. You also can't compile code against dllB and then drop dllA in and have it intercept method calls. Reflection could conceivably solve part of your problem, but you'd not want to base your code around calling all methods by reflection - it'd be horrendously unperformant and not very maintainable.
As Anton suggests, a plugin approach might work. However, this would rely on you being able to specify up-front the interface for your plugin, which sounds like it would contradict your original requirement.
Another problem: if you'd not deployed dllA until later, how would your ApplicationX know to call method start() in dll_one.dll anyway? You'd surely need to re-deploy at least the base application for that part to work.
These kinds of problem are often best solved by having a more specific set of requirements to work to: what functionality are you likely to want to extend or change in the future? Could you support a common set of interfaces that allow extensibility via plugins, or can you need to redeploy encapsulated chunks of your application with new functionality? Is there UI involved or is this just to change back-end logic? Questions like this could help to suggest more viable solutions.