With help of a compile-time integer list: #include <cstdlib> template <size_t… n> struct ct_integers_list { template <size_t m> struct push_back { typedef ct_integers_list<n…, m> type; }; }; template <size_t max> struct ct_iota_1 { typedef typename ct_iota_1<max-1>::type::template push_back<max>::type type; }; template <> struct ct_iota_1<0> { typedef ct_integers_list<> type; }; We could construct the tail simply by … Read more
With help of a compile-time integer list: #include <cstdlib> template <size_t… n> struct ct_integers_list { template <size_t m> struct push_back { typedef ct_integers_list<n…, m> type; }; }; template <size_t max> struct ct_iota_1 { typedef typename ct_iota_1<max-1>::type::template push_back<max>::type type; }; template <> struct ct_iota_1<0> { typedef ct_integers_list<> type; }; We could construct the tail simply by … Read more
How about this? val pair = query.getSingleOrNone pair collect { case Array(x: MyClass1, y: MyClass2, _*) => (x,y) } // result would be Option[(MyClass1, MyClass2)]
This isn’t simply “multiple variable assignment”, it’s fully-featured pattern matching! So the following are all valid: val (a, b) = (1, 2) val Array(a, b) = Array(1, 2) val h :: t = List(1, 2) val List(a, Some(b)) = List(1, Option(2)) This is the way that pattern matching works, it’ll de-construct something into smaller parts, … Read more
You can just do (a,). No need to use a function. (Note that the comma is necessary.) Essentially, tuple(a) means to make a tuple of the contents of a, not a tuple consisting of just a itself. The “contents” of a string (what you get when you iterate over it) are its characters, which is … Read more
Classic Example: You want to store point value as tuple of (x, y)
If you’re looking for fast, you can use numpy: >>> import numpy >>> numpy.subtract((10, 10), (4, 4)) array([6, 6]) and if you want to keep it in a tuple: >>> tuple(numpy.subtract((10, 10), (4, 4))) (6, 6)
The use case you’re mentioning, coming up with a tuple type for Object.keys(), is fraught with peril and I recommend against using it. The first issue is that types in TypeScript are not “exact”. That is, just because I have a value of type Person, it does not mean that the value contains only the … Read more
5 is immutable, too. When you have an immutable data structure, a += b is equivalent to a = a + b, so a new number, tuple or whatever is created. When doing this with mutable structures, the structure is changed. Example: >>> tup = (1, 2, 3) >>> id(tup) 140153476307856 >>> tup += (4, … Read more
The clearest way is just to construct each element in the tuple constructor argument list: template <typename… TElements> struct Container { Container(Foo foo, Bar bar) : tuple(TElements{foo, bar}…) {} std::tuple<TElements…> tuple; }; This will result in move (or copy) constructing each element of the tuple from its corresponding constructor parameter; if this is unacceptable you … Read more