method

enum_for

v1_8_7_330 - Show latest stable - 2 notes - Class: Object

enum_for(...) public

Returns Enumerable::Enumerator.new(self, method, *args).

e.g.:

str = "xyz"

enum = str.enum_for(:each_byte)
a = enum.map {|b| '%02x' % b } #=> ["78", "79", "7a"]

# protects an array from being modified
a = [1, 2, 3]
some_method(a.to_enum)

Show source

/*
 *  call-seq:
 *    obj.to_enum(method = :each, *args)
 *    obj.enum_for(method = :each, *args)
 *
 *  Returns Enumerable::Enumerator.new(self, method, *args).
 *
 *  e.g.:
 *
 *     str = "xyz"
 *
 *     enum = str.enum_for(:each_byte)
 *     a = enum.map {|b| '%02x' % b } #=> ["78", "79", "7a"]
 *
 *     # protects an array from being modified
 *     a = [1, 2, 3]
 *     some_method(a.to_enum)
 *
 */
static VALUE
obj_to_enum(argc, argv, obj)
    int argc;
    VALUE *argv;
    VALUE obj;
{
    VALUE meth = sym_each;

    if (argc > 0) {
        --argc;
        meth = *argv++;
    }
    return rb_enumeratorize(obj, meth, argc, argv);
}

August 23, 2008

4 thanks

Needs requiring 'enumerator' to work

This method needs that you

require 'enumerator'

for this method to be available.

May 27, 2009 - (>= v1_8_6_287)

3 thanks

map_with_index

If you want to access the element index when using map, you can do it with enum_for:

(1..6).enum_for(:each_with_index).map { |v, i| "index: #{i} value: #{v}" }
#=> ["index: 0 value: 1", "index: 1 value: 2", "index: 2 value: 3", "index: 3 value: 4", "index: 4 value: 5", "index: 5 value: 6"]

enum_for

Related methods

Needs requiring 'enumerator' to work

map_with_index