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Mediator Vs Observer Object-Oriented Design Patterns
...-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically.
The Mediator pattern:
Define an object that encapsulates how a set of objects interact. Mediator promotes loose coupling by keeping objects from referring to each o...
Android: upgrading DB version and adding new table
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1. About onCreate() and onUpgrade()
onCreate(..) is called whenever the app is freshly installed. onUpgrade is called whenever the app is upgraded and launched and the database version is not the same.
2. Incrementing the db version
You need a constructor like:
MyOpenHelp...
In a django model custom save() method, how should you identify a new object?
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Not all models have an id attribute, i.e. a model extending another through a models.OneToOneField(OtherModel, primary_key=True). I think you need to use self.pk
– AJP
Apr 9 '13 at 10:21
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Get model's fields in Django
Given a Django model, I'm trying to list all of its fields. I've seen some examples of doing this using the _meta model attribute, but doesn't the underscore in front of meta indicate that the _meta attribute is a private attribute and shouldn't be accessed directly? ... Because, for example, the ...
What is the difference between old style and new style classes in Python?
...(x) is always <type
'instance'>.
This reflects the fact that all old-style instances, independently of
their class, are implemented with a single built-in type, called
instance.
New-style classes were introduced in Python 2.2 to unify the concepts of class and type.
A new-s...
How can I read SMS messages from the device programmatically in Android?
...ForResult(intent, 1);
}else {
List<Sms> lst = getAllSms();
}
}else {
List<Sms> lst = getAllSms();
}
Set app as default SMS app
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == 1...
How to check if variable is string with python 2 and 3 compatibility
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What about this, works in all cases?
isinstance(x, ("".__class__, u"".__class__))
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Perforce for Git users? [closed]
...ou prefer Git you can use Git with Perforce quite well. We provide a tool called Git Fusion that generates Git repositories that are kept in sync with the Perforce server. Git and Perforce people can live in harmony working on the same code, mostly unaffected by their co-workers choice of version co...
Getting started with Haskell
...'ve done this by reading tutorials and watching screencasts, but nothing really seems to stick.
Now, in learning various imperative/OO languages (like C, Java, PHP), exercises have been a good way for me to go. But since I don't really know what Haskell is capable of and because there are many new c...
Mongoose populate after save
I cannot manually or automatically populate the creator field on a newly saved object ... the only way I can find is to re-query for the objects I already have which I would hate to do.
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