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Function std.range.only

Assemble values into a range that carries all its elements in-situ.

auto only(Values...) (
  scope return Values values
if (!is(CommonType!Values == void));

auto only();

Useful when a single value or multiple disconnected values must be passed to an algorithm expecting a range, without having to perform dynamic memory allocation.

As copying the range means copying all elements, it can be safely returned from functions. For the same reason, copying the returned range may be expensive for a large number of arguments.


values the values to assemble together


A RandomAccessRange of the assembled values.

The returned range can be sliced. Its elements can be assigned to if every type in Values supports assignment from the range's element type.

See Also

chain to chain ranges


import std.algorithm.comparison : equal;
import std.algorithm.iteration : filter, joiner, map;
import std.algorithm.searching : findSplitBefore;
import std.uni : isUpper;

assert(equal(only('♡'), "♡"));
writeln([1, 2, 3, 4].findSplitBefore(only(3))[0]); // [1, 2]

assert(only("one", "two", "three").joiner(" ").equal("one two three"));

string title = "The D Programming Language";
    .filter!isUpper // take the upper case letters
    .map!only       // make each letter its own range
    .joiner(".")    // join the ranges together lazily


Andrei Alexandrescu, David Simcha, Jonathan M Davis, and Jack Stouffer. Credit for some of the ideas in building this module goes to Leonardo Maffi.


Boost License 1.0.