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When do we have to use copy constructors?
I know that C++ compiler creates a copy constructor for a class. In which case do we have to write a user-defined copy constructor? Can you give some examples?
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Is it possible to move/rename files in Git and maintain their history?
...op jumping. It's not impossible, just tedious and possibly not worth it.
Now, since you're still with me, you're a probably solo developer renaming a completely isolated file. Let's move a file using filter-tree!
Assume you're going to move a file old into a folder dir and give it the name new
T...
How do I activate a virtualenv inside PyCharm's terminal?
...rrected version. This really saves a LOT of time.
Update:
Note: Pycharm now supports virtual environments directly and it seems to work well for me - so my workaround not needed anymore.
share
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How to use JavaScript source maps (.map files)?
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The .map files are for js and css (and now ts too) files that have been minified. They are called SourceMaps. When you minify a file, like the angular.js file, it takes thousands of lines of pretty code and turns it into only a few lines of ugly code. Hopefully, w...
What's the proper way to install pip, virtualenv, and distribute for Python?
...the environment.
$INITIAL_ENV/bin/pip install virtualenv-$VERSION.tar.gz
Now you can use your "bootstrap" environment to create more:
# Create a second environment from the first:
$INITIAL_ENV/bin/virtualenv py-env1
# Create more:
$INITIAL_ENV/bin/virtualenv py-env2
Go nuts!
Note
This assumes...
How to check if a Ruby object is a Boolean
...String".boolean?
=> false
>> 1.boolean?
=> false
>> Time.now.boolean?
=> false
>> nil.boolean?
=> false
>> true.boolean?
=> true
>> false.boolean?
=> true
>> (1 ==1).boolean?
=> true
>> (1 ==2).boolean?
=> true
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Elegant way to invert a map in Scala
... different keys associated with same values. So, if you are interested in knowing all the keys, here's the code:
scala> val m = Map(1 -> "a", 2 -> "b", 4 -> "b")
scala> m.groupBy(_._2).mapValues(_.keys)
res0: Map[String,Iterable[Int]] = Map(b -> Set(2, 4), a -> Set(1))
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Websocket API to replace REST API?
... Backbone.js (using Rails):
http://blog.pusher.com/2011/6/21/backbone-js-now-realtime-with-pusher
Build application with backbone.js on the client and node.js with express, socket.io, dnode on the server.
http://andyet.net/blog/2011/feb/15/re-using-backbonejs-models-on-the-server-with-node/
ht...
What is a practical use for a closure in JavaScript?
... privatefunction();
}
}
})();
As you can see there, a is now an object, with a method publicfunction ( a.publicfunction() ) which calls privatefunction, which only exists inside the closure. You can NOT call privatefunction directly (i.e. a.privatefunction() ), just publicfunction...
Multiple constructors in python? [duplicate]
...d
def fromfilename(cls, name):
return cls(open(name, 'rb'))
# Now you can do:
c = C(fd)
# or:
c = C.fromfilename('a filename')
Notice all those classmethods still go through the same __init__, but using classmethods can be much more convenient than having to remember what combinations...