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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. ...
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...
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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