class IO::Handle

Opened file or stream

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

Methods

method get

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

Read one line from the standard input:

$*IN.get;

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 -> $line {
        @data.push($line.split(','))
    }

method print

method print(*@text --> Bool)

Text writing; writes the given @text to the filehandle.

my $fh = open 'path/to/file', :w;
$fh.print("some text\n");
$fh.close;

method read

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

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.

$fh.close;

Related roles and classes

See also the related role IO and the related classes IO::FileTestable and IO::Path.

Type graph

Below you should see a clickable image showing the type relations for IO::Handle that links to the documentation pages for the related types. If not, try the PNG version instead.

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 close

To close an open file handle, simply call its close method:

my $fh = open("path/to/file");
# ... do stuff with the file
$fh.close;

It is also possible to call this as a sub, thus the example above can be written equivalently like so:

my $fh = open("path/to/file");
# ... do stuff with the file
close $fh;

When a file was opened for writing, closing it is important to ensure that all contents are actually written to the file.

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.

method list

Interprets the invocant as a list, and returns that list.

method flat

Interprets the invocant as a list, flattens it, and returns that list.

say ((1, 2), (3)).elems;        # 2
say ((1, 2), (3)).flat.elems;   # 3

method eager

Interprets the invocant as a list, evaluates it eagerly, and returns that list.

method elems

Interprets the invocant as a list, and returns the number of elements in the list.

method end

Interprets the invocant as a list, and returns the last index of that list.

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 = Point.new(-1, 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.

method WHERE

method WHERE() returns Int

Returns an Int representing the memory address of the object.

method WHY

multi method WHY()

Returns the attached Pod value. For instance,

    sub cast(Spell $s)
    #= Initiate a specified spell normally
    #= (do not use for class 7 spells)
    {
	do-raw-magic($s);
    }
    say &cast.WHY;

prints

Initiate a specified spell normally (do not use for class 7 spells)

See the documentation specification for details about attaching Pod to variables, classes, functions, methods, etc.

This documentation was generated from IO/Handle.pod.