class IO::Handle

class IO::Handle does IO::FileTestable { }


method get

Reads a single line from the input stream (usually the Standard Input or a file).

Read one line from the standard input:


Read one line from a file:

my $fh = open 'filename';
my $line = $fh.get;

method getc

Read a single character from the input stream.

method eof

Returns Bool::True if the read operations have exhausted the content of the file.

method lines

method lines($limit = Inf)

Return a lazy list of the file's lines read via get, limited to $limit lines.

    my @data;
    my $data-file = open 'readings.csv'
    for $data-file.lines -> $line {

method read

method read(IO::Handle:D: Cool:D $bytes as Int --> Buf)

Binary reading; reads and returns $bytes bytes from the handle

method write

method write(IO::Handle:D: Blob:D $buf)

Binary writing; writes $buf to the filehandle.

method seek

method tell

method slurp

method spurt

method close

Will close a previously opened filehandle.


Type graph

Below you should see an imgage showing the type relations for IO::Handle. If not, try the PNG version.

perl6-type-graph IO::Handle IO::Handle Any Any IO::Handle->Any IO IO IO::Handle->IO Mu Mu Any->Mu IO::ArgFiles IO::ArgFiles IO::ArgFiles->IO::Handle

Methods supplied by role IO

IO::Handle does role IO, which provides the following methods:

method prompt

sub prompt($msg)

Prints $msg to the standard output and waits for the user to type in something and finish with an ENTER. Returns the string typed in without the trailing newline.

my $name = prompt("Hi, what's your name? ");

method dir

sub dir(Cool $path = '.', Mu :$test = none('.', '..'))

Returns a list of IO::File and IO::Path objects for the files and directories found in the $path. If $path is not given assumes the current directory.

A second optional parameter can be given that will be matched against the strings to filter out certain entries. By default it filters out the '.' and '..' entries.


for dir() -> $file {
   say $file;

To include all the entries (including . and ..) write:

dir(test => all())

To include only entries with a .pl extension write:

dir(test => /.pl$/)

TODO: more IO Ops

Methods supplied by class Any

IO::Handle inherits from class Any, which provides the following methods:

method ACCEPTS

multi method ACCEPTS(Any:D: Mu $other)

Returns True if $other === self (i.e. it checks object identity).

method any

Interprets the invocant as a list and creates an any-Junction from it.

method all

Interprets the invocant as a list and creates an all-Junction from it.

method one

Interprets the invocant as a list and creates an one-Junction from it.

method none

Interprets the invocant as a list and creates an none-Junction from it.

Methods supplied by class Mu

IO::Handle inherits from class Mu, which provides the following methods:

method Str

multi method Str()   returns Str

Returns a string representation of the invocant, intended to be machine readable.

method clone

method clone(*%twiddles)

Creates a shallow clone of the invocant. If named arguments are passed to it, their values are used in every place where an attribute name matches the name of a named argument.

method new

multi method new(*%attrinit)

Default method for constructing (create + initialize) new objects of a class. This method expects only named arguments which are then used to initialize attributes with accessors of the same name.

Classes may provide their own new method to override this default.

method bless

method bless(*%attrinit) returns Mu:D

Lower-level object construction method than new.

Creates a new object of the same type as the invocant, uses the named arguments to initialize attributes, and returns the created object.

You can use this method when writing custom constructors:

class Point {
    has $.x;
    has $.y;
    multi method new($x, $y) {
        self.bless(:$x, :$y);
my $p =, 1);

(Though each time you write a custom constructor, remember that it makes subclassing harder).

method CREATE

method CREATE() returns Mu:D

Allocates a new object of the same type as the invocant, without initializing any attributes.

method print

multi method print() returns Bool:D

Prints value to $*OUT after stringification using .Str method without newline at end.

method say

multi method say() returns Bool:D

Prints value to $*OUT after stringification using .gist method with newline at end.

method ACCEPTS

multi method ACCEPTS(Mu:U: $other)

Performs a type check. Returns True if $other conforms to the invocant (which is always a type object or failure).

This is the method that is triggered on smart-matching against type objects, for example in if $var ~~ Int { ... }.

method WHICH

multi method WHICH() returns ObjAt:D

Returns an object of type ObjAt which uniquely identifies the object. Value types override this method which makes sure that two equivalent objects return the same return value from WHICH.