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Improve Enumerator.produce docs

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* Add to NEWS;
* Add examples of while-alike cycles with practical tasks.
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zverok 2019-10-26 14:02:59 +03:00 • committed by Nobuyoshi Nakada
parent aba23d83f2
commit 417369e0cd
Notes: git 2019-10-27 18:58:05 +09:00
2 changed files with 22 additions and 0 deletions
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7
NEWS
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@ -248,6 +248,13 @@ Enumerator::
New methods::
* Added Enumerator.produce to generate Enumerator from any custom
data-transformation. [Feature #14781]
require 'date'
dates = Enumerator.produce(Date.today, &:succ) #=> infinite sequence of dates
dates.detect(&:tuesday?) #=> next tuesday
* Added Enumerator::Lazy#eager that generates a non-lazy enumerator
from a lazy enumerator. [Feature #15901]

15
enumerator.c
View file

@ -2923,6 +2923,21 @@ producer_size(VALUE obj, VALUE args, VALUE eobj)
*
* ancestors = Enumerator.produce(node) { |prev| node = prev.parent or raise StopIteration }
* enclosing_section = ancestors.find { |n| n.type == :section }
*
* Using ::produce together with Enumerable methods like Enumerable#detect,
* Enumerable#slice, Enumerable#take_while can provide Enumerator-based alternative
* for +while+ and +until+ cycles:
*
* # Find next Tuesday
* require 'date'
* Enumerator.produce(Date.today, &:succ).detect(&:tuesday?)
*
* # Simple lexer:
* require 'strscan'
* scanner = StringScanner.new('7+38/6')
* PATTERN = %r{\d+|[-/+*]}
* p Enumerator.produce { scanner.scan(PATTERN) }.slice_after { scanner.eos? }.first
* # => ["7", "+", "38", "/", "6"]
*/
static VALUE
enumerator_s_produce(int argc, VALUE *argv, VALUE klass)