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Creating a singleton in Python
...mple implementation:
class Singleton(type):
_instances = {}
def __call__(cls, *args, **kwargs):
if cls not in cls._instances:
cls._instances[cls] = super(Singleton, cls).__call__(*args, **kwargs)
return cls._instances[cls]
class Logger(object):
__meta...
How to read a file in Groovy into a string?
...
Do I have to execute some close() statements or will the reader be closed by the getText() method?
– das Keks
Apr 29 '14 at 8:27
6
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How to “perfectly” override a dict?
...or other builtins) directly. It often makes no sense, because what you actually want to do is implement the interface of a dict. And that is exactly what ABCs are for.
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...
Get exception description and stack trace which caused an exception, all as a string
...
See the traceback module, specifically the format_exc() function. Here.
import traceback
try:
raise ValueError
except ValueError:
tb = traceback.format_exc()
else:
tb = "No error"
finally:
print tb
...
Bidirectional 1 to 1 Dictionary in C#
...turn firstToSecond.Count; }
}
/// <summary>
/// Removes all items from the dictionary.
/// </summary>
public void Clear()
{
firstToSecond.Clear();
secondToFirst.Clear();
}
}
...
How to serialize SqlAlchemy result to JSON?
...ps(e, cls=new_alchemy_encoder(), check_circular=False)
This would encode all children, and all their children, and all their children... Potentially encode your entire database, basically. When it reaches something its encoded before, it will encode it as 'None'.
A recursive, possibly-circular, s...
How to create the most compact mapping n → isprime(n) up to a limit N?
Naturally, for bool isprime(number) there would be a data structure I could query.
I define the best algorithm , to be the algorithm that produces a data structure with lowest memory consumption for the range (1, N], where N is a constant.
Just an example of what I am looking for: I could rep...
Android AsyncTask threads limits?
...ery time user logs in to the system, I also use database in the phone. For all those operations (updates, retrieving data from db and etc.) I use async tasks. As up till now I didn't see why I shouldn't use them, but recently I experienced that if I do some operations some of my async tasks simply s...
How to invoke the super constructor in Python?
In all other languages I've worked with the super constructor is invoked implicitly. How does one invoke it in Python? I would expect super(self) but this doesn't work.
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Are static class variables possible in Python?
... if it's a subclass. A static method lacks this information, so it cannot call an overridden method, for example.
– Seb
Oct 2 '12 at 15:58
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