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How to get one value at a time from a generator function in Python?
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In Python <= 2.5, use gen.next(). This will work for all Python 2.x versions, but not Python 3.x
In Python >= 2.6, use next(gen). This is a built in function, and is clearer. It will also work in Python 3.
Both of these end up calling a specially named function, next(), wh...
Simulate CREATE DATABASE IF NOT EXISTS for PostgreSQL?
...an work around it from within psql by executing the DDL statement conditionally:
SELECT 'CREATE DATABASE mydb'
WHERE NOT EXISTS (SELECT FROM pg_database WHERE datname = 'mydb')\gexec
The manual:
\gexec
Sends the current query buffer to the server, then treats each column of each row of the query's...
Foreign keys in mongo?
...his:
class Student
include Mongoid::Document
field :name
embeds_many :addresses
embeds_many :scores
end
class Address
include Mongoid::Document
field :address
field :city
field :state
field :postalCode
embedded_in :student
end
class Score
include Mongoi...
Check if OneToOneField is None in Django
... Thank you for this solution. Unfortunately, this doesn't work all the time. In case you want to work with select_related() now or in the future -- or maybe even to be sure you also handle other sorts of magic which may happen elsewhere -- you have to extend the test as follows: if hasat...
Rails params explained?
...e "1" and params[:boo] would be "octopus".
In HTTP/HTML, the params are really just a series of key-value pairs where the key and the value are strings, but Ruby on Rails has a special syntax for making the params be a hash with hashes inside. For example, if the user's browser requested
http://w...
Optional query string parameters in ASP.NET Web API
...ect using [FromUri] doesn't directly answer the original question. It basically says populate these models with the values from the Uri. The models properties would need to be nullable or a reference type in order for them to support being optional. Added additional information.
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Matplotlib: “Unknown projection '3d'” error
...e you using? (Try running: python -c 'import matplotlib; print matplotlib."__version__")
I'm guessing you're running version 0.99, in which case you'll need to either use a slightly different syntax or update to a more recent version of matplotlib.
If you're running version 0.99, try doing this in...
Python - abs vs fabs
...e about complex numbers. Out of interest, what other classes of things can __builtin__.abs() be successfully applied to?
– NPE
May 27 '12 at 7:31
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Scala: Nil vs List()
In Scala, is there any difference at all between Nil and List() ?
3 Answers
3
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Do declared properties require a corresponding instance variable?
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In your interface, you can formally declare an instance variable between the braces, or via @property outside the braces, or both. Either way, they become attributes of the class. The difference is that if you declare @property, then you can implement usin...