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rails 3 validation on uniqueness on multiple attributes
I use Rails 3.0.0.beta4
3 Answers
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Best way to find the intersection of multiple sets?
...tiple arguments to set.intersection(), like
u = set.intersection(s1, s2, s3)
If the sets are in a list, this translates to:
u = set.intersection(*setlist)
where *a_list is list expansion
Note that set.intersection is not a static method, but this uses the functional notation to apply intersec...
Pelican 3.3 pelican-quickstart error “ValueError: unknown locale: UTF-8”
When I was trying to use pelican3.3, I typed the commend "pelican-quickstart", some errors showed up.
6 Answers
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how to get first three characters of an NSString?
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3 Answers
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Active
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How to swap keys and values in a hash
... (in essence, by letting you access keys through values):
{a: 1, b: 2, c: 3}.key(1)
=> :a
If you want to keep the inverted hash, then Hash#invert should work for most situations:
{a: 1, b: 2, c: 3}.invert
=> {1=>:a, 2=>:b, 3=>:c}
BUT...
If you have duplicate values, invert will...
How to get one value at a time from a generator function in Python?
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answered Mar 10 '10 at 19:13
Ignacio Vazquez-AbramsIgnacio Vazquez-Abrams
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Initializing a member array in constructor initializer
...assignments in the body. This is what boost::array does.
Does the C++03 standard say anything special about initializing aggregates (including arrays) in ctor initializers? Or the invalidness of the above code is a corollary of some other rules?
A mem-initializer uses direct initialization. ...
Is it intended by the C++ standards committee that in C++11 unordered_map destroys what it inserts?
...obvious behaviour occurs in very recent compilers only: I found that clang 3.2-3.4 and GCC 4.8 are the only compilers to demonstrate this "feature".
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What's the difference between RANK() and DENSE_RANK() functions in oracle?
... assigned the same rank, with the next ranking(s) skipped. So, if you have 3 items at rank 2, the next rank listed would be ranked 5.
DENSE_RANK again gives you the ranking within your ordered partition, but the ranks are consecutive. No ranks are skipped if there are ranks with multiple items.
As...