Since WM_SHOWWINDOW (OnShowWindow) won't always be called per API docs, where do I process startup items that needs all CTreeView/CListView/etc.. of a CSplitterWnd() inside the CMainFrame populated? I can't do in OnCreate() since the OnInitialUpdate() for the CTreeView/CListView come after that.
TIA!!
I ended up adding my own method CMainFrame::OnAfterCreate() which is called inside CWinApp::InitInstance() after the CSigneDocTemplate is created.
Related
For my application I need to fetch some data asynchronously and do some initialization for each page. Unfortunately, a constructor does not allow me to make asynchronous calls. I followed this article and put all of my code into the OnAppearing method. However, since then I ran into multiple issues since each platform handles the event a little bit differently. For example, I have pages where you can take pictures, on iOS the OnAppearing is called again every time after the camera is closed while Android doesn't. It doesn't seem like a reliable method for my needs, which is also described here:
Calls to the OnDisappearing and OnAppearing overrides cannot be treated as guaranteed indications of page navigation. For example, on iOS, the OnDisappearing override is called on the active page when the application terminates.
I am searching for a method/way where I can perform my own initialization. The constructor would be perfect for that but I cannot perform anything asynchronously in there. Please do not provide me with any work arounds, I am searching for a solution that is the "recommended" way or maybe someone with a lot of experience can tell me what they are doing. (I also don't want to .Wait() or .Result as it will lock my app)
You can use Stephen Cleary's excellent NotifyTaskCompletion class.
You can read more how it works and what to do/don't in these cases in Microsoft's excellent Async Programming : Patterns for Asynchronous MVVM Applications: Data Binding. The highlights of this topics are:
Let’s walk through the core method
NotifyTaskCompletion.WatchTaskAsync. This method takes a task
representing the asynchronous operation, and (asynchronously) waits
for it to complete. Note that the await does not use
ConfigureAwait(false); I want to return to the UI context before
raising the PropertyChanged notifications. This method violates a
common coding guideline here: It has an empty general catch clause. In
this case, though, that’s exactly what I want. I don’t want to
propagate exceptions directly back to the main UI loop; I want to
capture any exceptions and set properties so that the error handling
is done via data binding. When the task completes, the type raises
PropertyChanged notifications for all the appropriate properties.
A sample usage of it:
public class MainViewModel
{
public MainViewModel()
{
UrlByteCount = new NotifyTaskCompletion<int>(
MyStaticService.CountBytesInUrlAsync("http://www.example.com"));
}
public NotifyTaskCompletion<int> UrlByteCount { get; private set; }
}
Here, the demo is about binding the returned asynchronous value to some bindable property, but of course you can you is without any return value (for simple data loading).
This may be too simple to say, but you CAN run asynchronous tasks in the constructor. Just wrap it in an anonymous Task.
public MyConstructor() {
Task.Run(async () => {
<Your code>
}
}
Be careful when doing this though as you can get into resource conflict issues if you accidentally open the page twice.
Another thing I like to do is use an _isInit flag, which indicates a first time use, and then never again.
How can I pass context from on asynchronous method call to another one - without using method parameters?
I need the feature to enrich log messages with a kind of flow ID so that I can easily trace all log messages of a specific call method flow.
I use Python's async and await keywords (Python 3.5.x).
You should use Context Variables introduced in Python 3.7, and I have a polyfill for Python < 3.7 as aiocontextvars.
Previous answer:
You may want to take a look at tasklocals and aiolocals.
I solved the problem by setting a custom task factory. It turned out that having a context per task (in comparison to a context per async call) was sufficient for me.
I'm working on aiotask-context package. It's a really simple way of passing context between tasks (called with await or yield from). If you don't wan't to use the package you can still use the idea :).
I'm working on how to propagate it for the ensure_future calls too.
import contextvars
c_id = contextvars.ContextVar("context_id", default=None)
def get_context_id():
return c_id.get()
def set_context_id(value):
c_id.set(value)
I struggled a lot for getting this right. If anyone is still searching for the answer then they can refer here. This works with Python3.7 onwards.
Create an instance of contextvars.ContextVar.
Here you can give the context variable name and a default value for that variable, the default value will be used in case the variable is not found in the current context.
Set the value using the setter and you can get the same value using the getter inside same context.
Define ContextVar at the top level once, and not inside closures(i.e. functions or class etc.) as garbage collection for context is not proper.
Looking for a decent observer of the Mage_Sendfriend module, when the product is sent to a friend. I just traced it and don't see anything immediately useful. There is one dispatch written in the module, which actually fires when the send to friend form is loaded, not when it's actually submitted.
Looking at the events triggered, here are some events you might use:
controller_action_postdispatch_sendfriend_product_sendmail
controller_action_postdispatch_sendfriend
controller_action_postdispatch
And in the function you want to use for this event:
$controller = $observer->getControllerAction();
... your code here
You might have to resort to observing the model_save_after and model_save_before events, then checking $observer->getEvent()->getObject() to see if it's the Mage_Sendfriend model you're looking for.
An ugly solution, but sometimes the events just don't line up to solve a problem nicely.
Good luck! Let us know if you find anything good!
Edit: I would also suggest against observing a controller for this, though, since that isn't very modular. If a third-party module provides another interface for the Sendfriend feature, it wouldn't work with your module if you observe controller actions.
You can dispatch custom events when and where you want.
Mage::dispatchEvent('any_name_for_your_custom_event',
array('key'=>$value,'key'=>$value,'key'=>$value)); //can pass how many values you want in this array.
And in your config you just make your nodes to look for this event, and call one method from observer.
Its simple.
I want to create a subscriber that gets triggered when the user tries to access the resource (which is a custom content-type). So, the object is not being added, modified, nothing, is just being traversed. Something like a Zope View Event.
So, basically, suppose a custom content type has a custom workflow (two states: private and viewed). The initial state is private. This content type is only going to be created programatically, using _createObjectByType by anonymous users. Suppose an object called myobjet was added, programatically, to the root folder of my Plone site.
What I want is: when the user access
http://localhost:8080/Plone/myobject
...it automatically changes the state of the workflow of this object to viewed. The url http://localhost:8080/Plone/myobject is going to be a custom view, not the default base_edit.
Which event should I use? I tried IEndRequestEvent and IBeforeTraverseEvent from this list and none of them work: the handler is not being called for my custom object interface.
I've tried other events with my custom object interface (like IObjectEditedEvent), and, for this event, my handler is called when I edit an object that implements the interface. But using IEndRequestEvent and IBeforeTraverseEvent doesn't call the handler.
IEndRequestEvent and IBeforeTraverseEvent only work when I set the subscriber to all interfaces:
<subscriber
for="*
zope.app.publication.interfaces.IBeforeTraverseEvent"
handler=".subscriber.myhandler"
/>
And when I make myhandler print the object and the event in this situation, it shows:
<PloneSite at Plone>
<zope.app.publication.interfaces.BeforeTraverseEvent object at 0xd52618c>
If the solution is to write an event myself, is there an easy tutorial for this?
You might want to have a look at http://pypi.python.org/pypi/plone.validatehook.
Make sure you bind the event to the right interface. If you bind it to "Interface" (as described on the plone.validatehook pypi page) the event will get called for every single request. In order to restrict the event to contentish objects you can do the following:
from Products.CMFCore.interfaces import IContentish
#adapter(IContentish, IPostValidationEvent)
def RedirectMember(object, event):
...
(Edit: I removed my first answer because it didn't work)
Not sure what this subscriber is supposed to do, but if the object is not being modified, added or whatsoever than I must suspect it will just be viewed...so why not just use the __call__ method of the items view (or the __update__ method if you are using five.grok/dexterity)?
How would it be possible to invoke a method at the end of Cocoa's main event loop after each iteration? I want to do the exact same thing that NSManagedObjectContext's -processPendingChanges does. According to the documentation, "In AppKit-based applications, this method is invoked automatically at least once during the event loop (at the end of the loop)." I need to do the same thing for one of my own methods. Is this possible? I've read documentation about NSRunLoop and NSApplication's -run method, but I haven't been able to find the solution to this problem. Any help would be much appreciated.
I believe you can achieve what you want by installing a CFRunLoopObserver. You can get the current CFRunLoopRef via CFRunLoopGetCurrent() or from an NSRunLoop via -[NSRunLoop getCFRunLoop].