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What is the use of ObservableCollection in .net?
...ed,
INotifyPropertyChanged
As such it is very useful when you want to know when the collection has changed. An event is triggered that will tell the user what entries have been added/removed or moved.
More importantly they are very useful when using databinding on a form.
...
how to solve “ruby installation is missing psych” error?
...ven though it was successfully installed, it complained about libyaml. and now every time i wanna install a gem (say rails) this warning shows up:
...
How to log out user from web site using BASIC authentication?
... @davidjb Since synchronous requests are considered deprecated now, an alternative solution might be to redirect the user in the callback of the async request.
– Hayden Schiff
Jul 31 '15 at 20:20
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How can I disable logging of asset pipeline (sprockets) messages in Ruby on Rails 3.1?
... end
alias_method_chain :call, :quiet_assets
end
end
Updated: It now works for Ruby on Rails 3.2 too (previous attempt fixes before_dispatch, and now we're going for the root rack call instead)
Update: A proper Rack middleware solution (instead of fragile alias_method_chain) from @macour...
How to determine if binary tree is balanced?
...IT specialist at a hospital. Trying to move to do some actual programming now. I'm working on binary trees now, and I was wondering what would be the best way to determine if the tree is height-balanced.
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Why does “pip install” inside Python raise a SyntaxError?
...
I know for me I had to do this from the command line (not python command line). This was after changing directory to the location of python.exe and then needed to put the file type on pip3. In my case I was after requests for HT...
Why would you use Oracle database? [closed]
...out the cost of developers time working with Oracle. Most developers who know any other db hate Oracle, those that don't assume that all DB code and/or ORM tools are difficult to use.
If I started a business that I believed was going to scale to Amazon proportions I might consider NoSQL solutions,...
What's the shebang/hashbang (#!) in Facebook and new Twitter URLs for?
...ve just noticed that the long, convoluted Facebook URLs that we're used to now look like this:
7 Answers
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Adding a column to a data.frame
...1, 1 + cumsum(nonpos))
> classes
[1] 1 1 1 1 2 2 2 2 2 2 2 3 3 3 3
Now, we can attach it back onto our data frame with cbind (by using the class= syntax, we can give the column the class heading):
> data_w_classes <- cbind(data, class=classes)
And data_w_classes now contains the re...
Is there a quicker / better way to clear the iPhone Simulator cache than deleting its directory?
...o the Keyboard Shortcut:. (I use command-period)
Click the Add button.
Now, while in your iOS Simulator, you can simply use your new shortcut key to reset.
If the Simulator doesn't appear in the drop down list:
In a Finder window, go to your Applications folder.
Right-click Xcode and choose...