One approach to implementing tuples is using multiple-inheritance. The tuple-elements are held by leaf-classes, and the tuple class itself inherits from multiple leafs. In pseudo-code: template<typename T0, typename T1, …, typename Tn> class PseudoTuple : TupleLeaf<0, T0>, TupleLeaf<1, T1>, …, TupleLeaf<n, Tn> { … }; Each leaf has an index, so that each base-class becomes … Read more
Although old question, with Swift evolving this question has new answer. I think that you approach is way better for the described situation, however original question was how to iterate over struct properties, so here is my answer(works both for classes and structs) You can use Mirror Structure Reference. The point is that after calling … Read more
Just a little update to this answer since C# 7 is out in the wild. Tuples have super powers now and can sometimes replace anonymous types and classes. Take for example this method that accepts and returns tuples with named properties. To help illustrate what is possible, the Whatever function transforms the input shape and … Read more
The canonical data structure for this type of queries is a dictionary: In [1]: t = ( …: (‘P’, ‘Shtg1’), …: (‘R’, u’Shtg2′), …: (‘D’, ‘Shtg3’), …: ) In [2]: d = dict(t) In [3]: d[‘P’] Out[3]: ‘Shtg1’ If you use a tuple, there is no way to avoid looping (either explicit or implicit).
l = [ (‘a’, 1), (‘a’, 2), (‘a’, 3), (‘b’, 1), (‘b’, 2), (‘c’, 1), ] d = {} for x, y in l: d.setdefault(x, []).append(y) print d produces: {‘a’: [1, 2, 3], ‘c’: [1], ‘b’: [1, 2]}
Alas, there is no magic in the tuples. Here’s the implementation GHC uses, and to give you some idea of what’s going on here’s the source for the last definition: data (,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,) a b c d e f g h i j k l m n o p q r s t u v w … Read more
I’m not aware of any existing class that does this, but it’s fairly easy to throw something together using a std::tuple and an indexing typelist: #include <tuple> #include <iostream> template<typename… Ts> struct typelist { template<typename T> using prepend = typelist<T, Ts…>; }; template<typename T, typename… Ts> struct index; template<typename T, typename… Ts> struct index<T, T, … Read more
for i, (letter, word) in enumerate(seq_nested): print i, letter, word
tuples I think i agree with you that the issue with what position corresponds to what variable can introduce confusion. But i think there are two sides. One is the call-side and the other is the callee-side: int remainder; int quotient; tie(quotient, remainder) = div(10, 3); I think it’s crystal clear what we got, but … Read more
Like this: public (DateTime Start, DateTime End) DateRanges { get { return (DateTime.MinValue, DateTime.MaxValue); } } Note: This requires a recent version of C# and .Net. Incidentally, watch out for this usage pattern: var from = filter?.DateRanges.Start; var to = filter?.DateRanges.End; That’s inefficient because it causes two identical tuples to be created. This is better: … Read more