I'm working in code generator project with the use of Xtend2. I want to use global variable. Right now I'm using map for that purpose. Is there any possibilities to declare global variable instead of map?
It's not entirely clear to me what a global variable means to you. You could use a static field in a class and access that, but in general I'd recommend to avoid these patterns and pass the necessary state into the methods that need it or hold it as local state in the instance that needs it.
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I've wondered where is the best place to store shared data and global vars in Angular 6.
I know I can set them on a service that can be injected to any of my components, but I'm sure there's a better practice...
Thanks in advance!
I am not sure it is the best practice, but if you want variable to be available in all places without any injections, you can use the global "window" object. it is not an angular way but if your project work with external libraries that didn't written in angular it can help you to communicate with it easily.
for example, you can type window.x = "something" to create new variable in the window object.
To avoid the moderators who don't like general questions, this is a Visio VBA one but I didn't want to include that in the title as it's a bit niche, and I guess the answer might be generic :-)
My code has the following variables:
Public gappVisio As Visio.Application
Public gdocFile As Visio.Document
Public gpagDiagram As Visio.Page
For those unfamilar with Visio, you create an application object, open the document, then set a reference to a page in the document where you can actually do some drawing.
All vars are global, but actually gdocFile is only used in my initialisation routine.
So my question is, do I need gdocFile as global, or can I just make it local?
I suppose I was worried that if it was local when it went out of scope it might tidy up the Document object, but I still need the page of the document?
Does that make sense?
Don't make a variable or object global unless you absolutely have to, which is almost never. Pass object references as parameters to those procedures that need them -- and only to those. Anything you need from the object before it "runs out of scope", as you say, should be passed to the calling procedure as Function return value (or, more obscurely hence less preferably, Sub ByRef parameter value).
When you say an object is out of scope, it's actually the reference to that object that is out of scope. The object still exists unaltered in memory.
Generally, global is bad and leads to difficult-to-maintain code, but exceptions could be things like universal constants, e.g.
Public Const PI As Double = 3.14159265358979
It's fine to have that as global.
In your case, the document lifetime is controlled by Visio application, the doc will not get cleaned up, no matter how many variables which refer to it you create, or in which scopes they are (global or local). Means, all reference counting (scoping) rules are simply ignored by Visio for documents in fact - the doc is not destroyed, even if there are no more references to it from your code.
You can tell Visio to close the document using document.close. After that call, any attempt to use document's (or page's) methods or properties using any of doc/page variables referring this document/page in this document will result in exception.
A doc may be closed by user. In this case all variables referring to it (or objects inside of it, such as pages or shapes) will become invalid.
Sometimes in debug mode with Flash Builder, I see something like
__AS3__.vec.Vector.<Object> (#909e219)
but when I try to store this variable in another as3 variable, Flash duplicate this variable. Concretly, I'm trying to exclude some values on dragInitiator.selectedItems property before adding them to a List but when I use splice method on it, values aren't deleted from this vector.
So how can I acces variable with __AS3__ namespace please ?
According to a Tamarin developer:
The namespace "__AS3__.vec" is an artifact of a time when we did not have good API
versioning and could not introduce new top-level names without the risk of breaking
existing code. Today we would probably have made "Vector" public & versioned.
Source: http://hg.mozilla.org/tamarin-redux/rev/817f3e019ba2#l2.30
In other words, __AS3__ is the package where are defined Flash internal classes into Tamarin VM.
To access such variables, you don't need to specify the namespace. You only have to use the FQN declared in playerglobals.swc.
I'm confused. SharedObject seems have two ways to store value in it, by data and setProperty():
so.data.foo = 'bar';
so.setProperty('boo', 'bar');
What's the different? And why doesn't it have getProperty()?
From the SharedObject reference: setProperty() marks a property as "dirty" in addition to setting it, which you need to do if you're using a remote SharedObject, as it tells the server that the value needs to be updated in other clients.
It's slightly more convenient than manually setting the property and then calling setDirty(), and there's obviously no need to for a similar getProperty() method, as the server doesn't need to be informed when you do that.
In Flex, I want to create some variable that would hold a dictionary of ui components used throughout my application. Ideally, there would be a function in Application component that would return component for id:
public function getComponent4Id(id:String):UIComponent {}
Then I would access component using the following line:
var myComponent:UIComponent = FlexGlobals.topLevelApplication.getComponent4Id("someId");
Now, the only problem is: I want the component returned to be read-only.
It is very convenient to read some properties of myComponent from every corner of application, but I don't want my developers to abuse it and change myComponent.
Is it possible to return a copy of myComponent? Or is it possible to make it read-only somehow?
In the situation you describe, it is not possible to retrieve read only components.
You can create read only variables by implementing get methods without set methods. Something like this:
public var get myValue():UIComponent{
return UIComponent;
}
This would allow you to retrieve the UIComponent instance, myValue, from the component; but you would not be able to set it.
However, this would not prevent people from changing properties on the returned UIComponent unless those properties were also implemented as read only.
I'll add that there is already a method, getChildByName() to retrieve a child component by name. If you have an instance to a parent, you can use this to access the children.
All that said, I'm not sure I completely understand what you hope to achieve; with this functionality.