In GDBus it's possible to watch for a particular name to appear on the bus with g_bus_watch_name_on_connection(). It's also possible to be notified about new interfaces/objects added on objects implementing the org.freedesktop.DBus.ObjectManager interface. I cannot however find a way to be notified about the appearance of the top-level ObjectManager on the bus. In other words:
We have a name org.foobar which exports an ObjectManager at /org/foobar which manages /org/foobar/abc and /org/foobar/xyz.
I can get notified about the name acquisition of org.foobar and about the addition of /org/foobar/abc and /org/foobar/xyz. However some time passes between when the org.foobar name is taken and then the /org/foobar object appears. How do I programmatically and correctly wait for it in GLib?
Related
How is the PropertyChanged event used?
I'm wanting to evaluated the next state of a state machine whenever any property of the class is changed.
Regards Steve
PropertyChanged is part of the standard IPropertyNotifyChanged signaling.
If you want to create side effects if any change is done - consider setting "HasUserCode" on each attribute, Generate code, now you will find a partial method available for you to fill for Set and Get of attributes.
In a setter you can have side effects like running a trigger to step a state machine.
I am using Doctrine 2 entities. We have some entities which have to update related items when they are saved to the database. For example, when a user record is modified, we save it as a new record, with the "inactive" field set to 'false'. However, we have to set the the 'inactive' field for all previous record for that user to 'true'. This is done to keep an audit history. It is a Legacy database, so changing the structure is not an option.
Since Doctrine saves objects by passing them to a persister object (persist::($thisObj)), rather than the object having a save method ($thisObj->save()), we can't just extend a 'save' method from a parent object. The only option I see here is to try to extend the 'persist' object, but that sounds like a goose gaggle, just waiting to happen.
I found some information on events, but do not see how to add them to make events fire a particular function when a particular entity is persisted.
How do I add pre-save/post-save functionality to some of my entities ?
So, you probably already know http://www.doctrine-project.org/docs/orm/2.1/en/reference/events.html right?
You add an annotation that the entity contains callbacks and then create specific functions (which need to be public) on that entity and also annotate them with #PrePersist or #PostPersist or whatever.
The other way is creating an event subscriber, register that one with the doctrine event manager and implement methods called prePersist, postPersist etc. They get passed an EventArguments object which contains the entity relevant for the occurred event.
I know this is a very general answer to your question, but you need to be a bit more specific where your problem lies.
Please dont exend the entity manager and overwrite the persist method, there are way cleaner methods for doing what you need as far as I can tell.
It's actually quite simple to do what you want to do. It does not require dorking with the event manager, or anything complex like that. You use something called "Lifecycle callbacks". These are functions that Doctrine automatically runs during the "lifecycle" of the entity, ie: prePersist, postPersist, preUpdate, postUpdate, etc. You can find the complete list here: http://www.doctrine-project.org/docs/orm/2.0/en/reference/events.html
The process of adding this functionality to your entities is very simple.
In the Annotations section of your entity, include the following tag: "#HasLifecycleCallbacks". This tells Doctrine that it should search the entity for functions to run upon various events
Write a public function in your entity that you would like to fire upon a specific event.
Put an annotation above the function indicating which event it should be used to handle.
For example, look at the following code:
/** #PostPersist */
public function doSPostPersist() {
$this->tester = 'Value changed by post-persist';
}
I have found that sometimes the events simply refuse to fire, and I don't yet know why. But when they do fire, they will fire reliably.
Don't forget to enable Lifecycle Callbacks in your class annotation :
/**
* Report\MainBundle\Entity\Serveur
* #ORM\HasLifecycleCallbacks
*/
class Serveur {
"core" refers to the initial piece of the application that is loaded.
In order to bind url to places, GWT uses PlaceTokenizer<P extends Place>. When loading the application from the url, it calls the method P getPlace(String token) to retrieve a new instance of the place to call.
due to the asynchronous nature of code splitting, I can't create the place inside a runAsync in this method. So I have to put all the places of my app in the core.
To link places to activity, GWT callsActivity getActivity(Place place) (from com.google.gwt.activity.shared.ActivityMapper) to retrieve a new instance of the activity.
Once again, i have to put all my activities in the core.
Here's what I want to try: Write a custom com.google.gwt.place.shared.Delegate that
bind itself on PlaceChangeRequestEvent. If the AppPiece corresponding to the requestedPlace isn't loaded, it calls event.setWarning(NEED_TO_LOAD_MODULE)
in the confirm(String message) method, always return false when the message equals NEED_TO_LOAD_MODULE (so it doesn't bother the user), and load the module via RunAsync.
Once the module is loaded, call goTo(requestedPlace)
Each AppPiece of my application contains a bunch of activies and the corresponding views. Since the mappers are only called when PlaceChangeEventis fired, i could generate a new instance of my activity via AppPiece.getSomeActivityInstance().
I'm pretty sure this will work, but what bother me is that
Finding wich AppPiece to load depending on the requestedPlace will force me to write code that will be very similar to my mappers
I would like to have my places inside the corresponding AppPiece
Overriding Delegate for this purpose is tricky, and I'm looking for a better solution
You don't have to put all your activities in the core (as you call it): while an Activity instance is retrieved synchronously, it's allowed to start asynchronously. This is where you'd put your GWT.runAsync call.
See http://code.google.com/p/google-web-toolkit/issues/detail?id=5129 and https://groups.google.com/d/topic/google-web-toolkit/8_P_d4aT-0E/discussion
I am trying to figure out the best way to design something. I am writing an iPhone App and for the most part I am using async calls to a web service. This means that I cam setting up a URLConnection, calling start and letting it call me back when the data is available or an exception occurs. This works well and I think is the correct way to handle things.
For example:
I request a list of people from a web service. The resulting list is Xml Person elements which will be translated into an objective-c "Person" object by my XmlDelegate.
When I call the function to get the person, I pass in a "PersonResultDelegate", which is a protocol with a single function called "PersonReceived:(Person *)p". So, each time I get a complete Person object, I call that method and all is well. So, my detail view (or search result view) just receives the elements as they are available.
The problem comes when I need to obtain more then one specific object. In my specific case, I need to get the first and last appointment for a person. So, I need to make two API calls to obtain these two single Appointment objects. Each Appointment object will result in a call to the registered AppointmentResultDelegate, but how will I know which is the first and which is the last? I also need to somehow handle the case when there is no "first" or "last" Appointments and the Delegate will never get called.
What would be the correct way design wise to handle this? Should I add some additional context information to the initial request which is passed back to the handle in the delegate? An opaque piece of data which only makes sense to the person who made the initial call? What are my other options?
Solution
What I actually ended up doing is just passing an opaque piece of data along with the Appointment to the delegate. So, when I request an appointment object I have a method like:
getNextAppointment withDelegate:self withContext:#"next"
getPrevAppointment withDelegate:self withContext:#"prev"
This way when the delegate gets called I know what appointment is being delivered.
"Each Appointment object will result in a call to the registered AppointmentResultDelegate, but how will I know which is the first and which is the last?"
By looking at the order in which you receive these callbacks. Or by looking at some value in that xml data. Like a sequence or data. I don't know your data of course.
I'm implementing a Custom Workflow and Activities to be reused in multiple projects and trying to get them to be as easy to use as possible. In this workflow I have a Property whose name is 'UserID' which I'd like to bind to a dependencyproperty in one of my activities. I can currently bind it at design time searching explicitly for the property each time I add one of these activities to the workflow, but I'd like for this activity to be binded automatically.
As far as i know (correct me if I'm wrong), to bind a dependency property at design time I need to specify a string of the form "Activity=NameOfWorkflow, Path=UserID" to the DefaultBindingProperty metadata tag, and I'd like the name of the workflow to be completed in some way. Any way of doing this?
Thanks
I finally managed to achieve this by attaching an ActivityToolboxItem to the Activity, and overriding a method in it that creates the instance shown in the designer. I used an ActivityBind object to bind the dependencyproperty to the workflow's property. To get the instance of the workflow, I just searched for an ancestor to my activity by calling act.Parent until the activity had no parent (and thus was the StateMachineWorkflowActivity itself)