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belongs_to through associations
...ave a :through option. You're better off caching the question_id on Choice and adding a unique index to the table (especially because validates_uniqueness_of is prone to race conditions).
If you're paranoid, add a custom validation to Choice that confirms that the answer's question_id matches, but ...
How does the @property decorator work in Python?
I would like to understand how the built-in function property works. What confuses me is that property can also be used as a decorator, but it only takes arguments when used as a built-in function and not when used as a decorator.
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Write a program to find 100 largest numbers out of an array of 1 billion numbers
... number in the queue (the head of the queue), remove the head of the queue and add the new number to the queue.
EDIT:
as Dev noted, with a priority queue implemented with a heap, the complexity of insertion to queue is O(logN)
In the worst case you get billionlog2(100) which is better than billion...
SQL RANK() versus ROW_NUMBER()
...rows that have duplicate values,in which case the same ranking is assigned and a gap appears in the sequence for each duplicate ranking.
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C# Events and Thread Safety
... be out of date, but that's all. It won't cause a NullReferenceException.
And yes, there's certainly a race condition - but there always will be. Suppose we just change the code to:
TheEvent(this, EventArgs.Empty);
Now suppose that the invocation list for that delegate has 1000 entries. It's per...
Change key pair for ec2 instance
...e it in the same subnet, otherwise you will have to terminate the instance and create it again. - see here
Attach volume A to the new micro instance, as /dev/xvdf (or /dev/sdf)
SSH to the new micro instance and mount volume A to /mnt/tmp
$ sudo mount /dev/xvdf1 /mnt/tmp
Copy ~/.ssh/authorized_keys ...
Does Javascript pass by reference? [duplicate]
...out my parameter for the rectangle function. It is actually undefined , and redefined inside the function. There are no original reference. If I remove it from the function parameter, the inside area function is not able to access it.
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Is there a decorator to simply cache function return values?
... @Jonathan It works, but wrongly. If I pass a hashable, mutable argument, and change the value of the object after the first call of the function, the second call will return the changed, not the original, object. That is almost certainly not what the user wants. For it to work for mutable argume...
API pagination best practices
I'd love some some help handling a strange edge case with a paginated API I'm building.
11 Answers
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Setting unique Constraint with fluent API?
I'm trying to build an EF Entity with Code First, and an EntityTypeConfiguration using fluent API. creating primary keys is easy but not so with a Unique Constraint. I was seeing old posts that suggested executing native SQL commands for this, but that seem to defeat the purpose. is this possible ...