method

enum_for

v1_9_3_392 - Show latest stable - 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)

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);
}

2Notes

Needs requiring 'enumerator' to work

yonosoytu · Aug 23, 20084 thanks

This method needs that you

require 'enumerator'

for this method to be available.

map_with_index

rob-twf · May 26, 20093 thanks

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

Example

2Notes

Needs requiring 'enumerator' to work

map_with_index

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