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Error: could not find function … in R
...hat contains the function? install.packages("thePackage") (this only needs to be done once)
Did you attach that package to the workspace ?
require(thePackage) or library(thePackage) (this should be done every time you start a new R session)
Are you using an older R version where this function didn'...
Google Guice vs. PicoContainer for Dependency Injection
My team is researching dependency injection frameworks and is trying to decide between using Google-Guice and PicoContainer.
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What is the difference between encrypting and signing in asymmetric encryption?
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When encrypting, you use their public key to write a message and they use their private key to read it.
When signing, you use your private key to write message's signature, and they use your public key to check if it's really yours.
I want to use my private key to g...
Objective-C: Where to remove observer for NSNotification?
...removeObserver: self] in method dealloc of those classes, which you intend to use as observers, as it is the last chance to unregister an observer cleanly. This will, however, only protect you against crashes due to the notification center notifying dead objects. It cannot protect your code against ...
How to use the pass statement?
...uppose you are designing a new class with some methods that you don't want to implement, yet.
class MyClass(object):
def meth_a(self):
pass
def meth_b(self):
print "I'm meth_b"
If you were to leave out the pass, the code wouldn't run.
You would then get an:
IndentationE...
How should I unit test threaded code?
...the nightmare that is testing multi-threaded code since it just seems like too much of a minefield. I'd like to ask how people have gone about testing code that relies on threads for successful execution, or just how people have gone about testing those kinds of issues that only show up when two th...
What are the use cases for selecting CHAR over VARCHAR in SQL?
...ed-width. But, so what? Why not just pick VARCHAR for all text fields just to be safe.
19 Answers
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What is meant by immutable?
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Immutable means that once the constructor for an object has completed execution that instance can't be altered.
This is useful as it means you can pass references to the object around, without worrying that someone else is going to change its contents. Especiall...
Create a tag in a GitHub repository
I have a repository in GitHub and I need to tag it.
I tagged in a shell, but on GitHub , it is not showing up.
7 Answ...
iOS 6 apps - how to deal with iPhone 5 screen size? [duplicate]
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All apps will continue to work in the vertically stretched screen from what I could tell in today's presentation. They will be letterboxed or basically the extra 88 points in height would simply be black.
If you only plan to support iOS 6+, then d...