Raise event in constructor

1

@Joost

of course you can
in your constructors call just call raiseEvent

2

but don’t you have to be careful … if the event references the object being constructed as it might not be fully (welll uh) contstructed.

Wouldn’t OPEN be safer?

3

No
Xojo constructors are more like java’s where the object IS fully constructed and they are just a spot to do initialization
Its why you can even call them JUST like normal methods if you want to re-initialize the object

4

Unlike the INIT routine in Swift then… the object isn’t “SELF” until the super.init is complete

5

Yeah constructors in C++ are similar
Since they are called as part of actually allocating the memory etc

In Xojo & Java the “constructor” is an “initializer” and all memory is already set aside AND everything is already set to default values
I assume internally they use a call to calloc which sets all memory to 0

6

I am getting confused now Norman - @npalardy - I work with evens all the time, but events raised within a Constructor method never arrive. Greg o’Lone seems to agree with me.

7

Here’s an example with raise event IN The app constructor

http://great-white-software.com/gws-rb-samples/formarkus.xojo_binary_project

IF you use that exact same design, a subclassed control, and put a raiseevent in ITS constructor it WONT be raised

So the answer isnt consistent and depends on what it is you’re trying to do this with

8

Hi Norman, the links isn’t working.
in fact i create an object sometime after launching the app, another proces triggers it. And within the constructor of this class/object I want to raise events in order to have a sort of a working-trail. The project is in fact a Windows service, no controls.

9

sorry my bad
link fixed

Whats going to listen to those events being raised ?
You cant hook up listeners using addhandler before the class exists like

AddHandler myInstance.EventDuringConstruction, AddressOf EventDuringConstructor

myInstance = New Class

You get a nil object exception

10

Hi Norman, you gave a good example of having the supper of the app = class1. Understood. But as I am building some business objects (classes) for having in my library, I want them to be created and be used when needed by the (web/desktop) app, for example when the user wants to create a new project within the app, I setup a new datafile by using the businessobject to do so. It’s also possible that the user has multiple objects running. And since a lot can go wrong, I need to be able to receive events during (in fact after) the construction of the object. So, what I intend to do now is to create a one-shot timer object within the class and let this timer raise all collected events 1 ms after finalizing the construction.

11

Yeah thats about as close as you’ll get with certain patterns

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