From 5253b9579a129f66a768dae24bd50a95bab02841 Mon Sep 17 00:00:00 2001 From: Victor Shepelev Date: Mon, 21 Dec 2020 02:32:30 +0200 Subject: Document usage of ArithmeticSequence in Array#slice, and add to NEWS (#3952) --- array.c | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-) (limited to 'array.c') diff --git a/array.c b/array.c index f4c3e27af7..ea84473fdf 100644 --- a/array.c +++ b/array.c @@ -1775,11 +1775,22 @@ static VALUE rb_ary_aref2(VALUE ary, VALUE b, VALUE e); * a[4..0] # => nil * a[4..-1] # => nil * - * When a single argument +aseq+ is given, - * ...(to be described) - * - * Raises an exception if given a single argument - * that is not an \Integer-convertible object or a \Range object: + * When a single Enumerator::ArithmeticSequence argument +aseq+ is given, + * returns an Array of elements corresponding to the indexes produced by + * the sequence. + * a = ['--', 'data1', '--', 'data2', '--', 'data3'] + * a[(1..).step(2)] # => ["data1", "data2", "data3"] + * + * Unlike slicing with range, if the start or the end of the arithmetic sequence + * is larger than array size, throws RangeError. + * a = ['--', 'data1', '--', 'data2', '--', 'data3'] + * a[(1..11).step(2)] + * # RangeError (((1..11).step(2)) out of range) + * a[(7..).step(2)] + * # RangeError (((7..).step(2)) out of range) + * + * If given a single argument, and its type is not one of the listed, tries to + * convert it to Integer, and raises if it is impossible: * a = [:foo, 'bar', 2] * # Raises TypeError (no implicit conversion of Symbol into Integer): * a[:foo] -- cgit v1.2.3