Method: Date#<<

Defined in:

date_core.c

#<<(n) ⇒ Object

Returns a new Date object representing the date n months earlier; n should be a numeric:

(Date.new(2001, 2, 3) << 1).to_s  # => "2001-01-03"
(Date.new(2001, 2, 3) << -2).to_s # => "2001-04-03"

When the same day does not exist for the new month, the last day of that month is used instead:

(Date.new(2001, 3, 31) << 1).to_s  # => "2001-02-28"
(Date.new(2001, 3, 31) << -6).to_s # => "2001-09-30"

This results in the following, possibly unexpected, behaviors:

d0 = Date.new(2001, 3, 31)
d0 << 2      # => #<Date: 2001-01-31>
d0 << 1 << 1 # => #<Date: 2001-01-28>

d0 = Date.new(2001, 3, 31)
d1 = d0 << 1  # => #<Date: 2001-02-28>
d2 = d1 << -1 # => #<Date: 2001-03-28>

# File 'date_core.c', line 6507

static VALUE
d_lite_lshift(VALUE self, VALUE other)
{
    expect_numeric(other);
    return d_lite_rshift(self, f_negate(other));
}