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std.typecons.Tuple.rename - multiple declarations

Function Tuple.rename

Renames the elements of a Tuple.

ref auto rename(names...)() return
if (names.length == 0 || allSatisfy!(isSomeString, typeof(names)));

rename uses the passed names and returns a new Tuple using these names, with the content unchanged. If fewer names are passed than there are members of the Tuple then those trailing members are unchanged. An empty string will remove the name for that member. It is an compile-time error to pass more names than there are members of the Tuple.

Example

auto t0 = tuple(4, "hello");

auto t0Named = t0.rename!("val", "tag");
writeln(t0Named.val); // 4
writeln(t0Named.tag); // "hello"

Tuple!(float, "dat", size_t[2], "pos") t1;
t1.pos = [2, 1];
auto t1Named = t1.rename!"height";
t1Named.height = 3.4f;
writeln(t1Named.height); // 3.4f
writeln(t1Named.pos); // [2, 1]
t1Named.rename!"altitude".altitude = 5;
writeln(t1Named.height); // 5

Tuple!(int, "a", int, int, "c") t2;
t2 = tuple(3,4,5);
auto t2Named = t2.rename!("", "b");
// "a" no longer has a name
static assert(!hasMember!(typeof(t2Named), "a"));
writeln(t2Named[0]); // 3
writeln(t2Named.b); // 4
writeln(t2Named.c); // 5

// not allowed to specify more names than the tuple has members
static assert(!__traits(compiles, t2.rename!("a","b","c","d")));

// use it in a range pipeline
import std.range : iota, zip;
import std.algorithm.iteration : map, sum;
auto res = zip(iota(1, 4), iota(10, 13))
    .map!(t => t.rename!("a", "b"))
    .map!(t => t.a * t.b)
    .sum;
writeln(res); // 68

Function Tuple.rename

Overload of rename that takes an associative array translate as a template parameter, where the keys are either the names or indices of the members to be changed and the new names are the corresponding values. Every key in translate must be the name of a member of the tuple. The same rules for empty strings apply as for the variadic template overload of rename.

ref auto rename(alias translate)()
if (is(typeof(translate) : V[K], V, K) && isSomeString!V && (isSomeString!K || is(K : size_t)));

Example

//replacing names by their current name

Tuple!(float, "dat", size_t[2], "pos") t1;
t1.pos = [2, 1];
auto t1Named = t1.rename!(["dat": "height"]);
t1Named.height = 3.4;
writeln(t1Named.pos); // [2, 1]
t1Named.rename!(["height": "altitude"]).altitude = 5;
writeln(t1Named.height); // 5

Tuple!(int, "a", int, "b") t2;
t2 = tuple(3, 4);
auto t2Named = t2.rename!(["a": "b", "b": "c"]);
writeln(t2Named.b); // 3
writeln(t2Named.c); // 4

Example

//replace names by their position

Tuple!(float, "dat", size_t[2], "pos") t1;
t1.pos = [2, 1];
auto t1Named = t1.rename!([0: "height"]);
t1Named.height = 3.4;
writeln(t1Named.pos); // [2, 1]
t1Named.rename!([0: "altitude"]).altitude = 5;
writeln(t1Named.height); // 5

Tuple!(int, "a", int, "b", int, "c") t2;
t2 = tuple(3, 4, 5);
auto t2Named = t2.rename!([0: "c", 2: "a"]);
writeln(t2Named.a); // 5
writeln(t2Named.b); // 4
writeln(t2Named.c); // 3

Authors

Andrei Alexandrescu, Bartosz Milewski, Don Clugston, Shin Fujishiro, Kenji Hara

License

Boost License 1.0.