method

enum_for

v1_9_3_125 - Show latest stable - 2 notes - Class: Object

enum_for(*args) public

Creates a new Enumerator which will enumerate by on calling method on obj.

`method`	the method to call on `obj` to generate the enumeration
`args`	arguments that will be passed in `method` in addition

to the item itself.  Note that the number of args
must not exceed the number expected by +method+

Example

str = "xyz"

enum = str.enum_for(:each_byte)
enum.each { |b| puts b }
# => 120
# => 121
# => 122

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

Show source

static VALUE
obj_to_enum(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

Example

Needs requiring 'enumerator' to work

map_with_index