Preview Ruby 4.1 is a preview. It can change before the final release. Switch to Ruby 4.0 →
class method
IO.open
(::int fd, ?::string | ::int mode, ?path: ::string?, ?external_encoding: ::String | ::Encoding | nil, ?internal_encoding: ::String | ::Encoding | nil, ?encoding: ::String | ::Encoding | nil, ?textmode: ::boolish, ?binmode: ::boolish, ?autoclose: ::boolish, ?mode: ::String) -> instance
[X] (::int fd, ?::string | ::int mode, ?path: ::string?, ?external_encoding: ::String | ::Encoding | nil, ?internal_encoding: ::String | ::Encoding | nil, ?encoding: ::String | ::Encoding | nil, ?textmode: ::boolish, ?binmode: ::boolish, ?autoclose: ::boolish, ?mode: ::String) { (instance) -> X } -> X
IO.open(fd, mode = 'r', **options) → io
IO.open(fd, mode = 'r', **options) {|io| ... } → object
io.c
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static VALUE
rb_io_s_open(int argc, VALUE *argv, VALUE klass)
{
VALUE io = rb_class_new_instance_kw(argc, argv, klass, RB_PASS_CALLED_KEYWORDS);
if (rb_block_given_p()) {
return rb_ensure(rb_yield, io, io_close, io);
}
return io;
}
Creates a new IO object via IO.new with the given arguments.
With no block given, returns the IO object.
With a block given, calls the block with the IO object, closes the IO object, and returns the block’s value:
Example
fd = File.sysopen('doc/maintainers.md') # => 6 IO.open(fd) {|io| io.read.size } # => 14897