W3cubDocs

/Crystal

struct Symbol

Overview

A symbol is a constant that is identified by a name without you having to give it a numeric value.

:hello
:welcome
:"123"
:"symbol with spaces"

Internally a symbol is represented as an Int32, so it's very efficient.

You can't dynamically create symbols. When you compile your program, each symbol gets assigned a unique number.

Included Modules

Defined in:

json/to_json.cr
primitives.cr
symbol.cr
yaml/to_yaml.cr

Class Method Summary

Instance Method Summary

Instance methods inherited from module Comparable(Symbol)

<, <=(other : T) <=, <=>(other : T) <=>, ==(other : T) ==, >(other : T) >, >=(other : T) >=, clamp(min, max)
clamp(range : Range) clamp

Instance methods inherited from struct Value

==(other : JSON::Any)
==(other : YAML::Any)
==(other) ==, dup dup

Instance methods inherited from class Object

! : Bool !, !=(other) !=, !~(other) !~, ==(other) ==, ===(other : JSON::Any)
===(other : YAML::Any)
===(other) ===, =~(other) =~, as(type : Class) as, as?(type : Class) as?, class class, dup dup, hash(hasher)
hash hash, in?(*values : Object) : Bool
in?(collection) : Bool in?, inspect : String
inspect(io : IO) : Nil inspect, is_a?(type : Class) : Bool is_a?, itself itself, nil? : Bool nil?, not_nil! not_nil!, pretty_inspect(width = 79, newline = "\n", indent = 0) : String pretty_inspect, pretty_print(pp : PrettyPrint) : Nil pretty_print, responds_to?(name : Symbol) : Bool responds_to?, tap(&) tap, to_json(io : IO)
to_json to_json, to_pretty_json(io : IO, indent : String = " ")
to_pretty_json(indent : String = " ") to_pretty_json, to_s : String
to_s(io : IO) : Nil to_s, to_yaml(io : IO)
to_yaml to_yaml, try(&) try, unsafe_as(type : T.class) forall T unsafe_as

Class methods inherited from class Object

from_json(string_or_io, root : String)
from_json(string_or_io) from_json, from_yaml(string_or_io : String | IO) from_yaml

Class Method Detail

def self.needs_quotes?(string) : BoolSource

Determines if a string needs to be quoted to be used for a symbol.

Symbol.needs_quotes? "string"      # => false
Symbol.needs_quotes? "long string" # => true

Instance Method Detail

def !=(other : Symbol) : BoolSource

Returns true if self is not equal to other.

def <=>(other : Symbol)Source

Compares symbol with other based on String#<=> method. Returns -1, 0 or 1 depending on whether symbol is less than, equal to, or greater than other.

See String#<=> for more information.

def ==(other : Symbol) : BoolSource

Returns true if self is equal to other.

def cloneSource

def hash(hasher)Source

See Object#hash(hasher)

def inspect(io : IO) : NilSource

Returns the symbol literal representation as a string.

:crystal.inspect # => ":crystal"

def to_i : Int32Source

Returns a unique number for this symbol.

def to_json(json : JSON::Builder)Source

def to_json_object_keySource

def to_s(io : IO) : NilSource

Appends the symbol's name to the passed IO.

:crystal.to_s # => "crystal"

def to_s : StringSource

Returns the symbol's name as a String.

:foo.to_s           # => "foo"
:"hello world".to_s # => "hello world"

def to_yaml(yaml : YAML::Nodes::Builder)Source

© 2012–2020 Manas Technology Solutions.
Licensed under the Apache License, Version 2.0.
https://crystal-lang.org/api/0.35.1/Symbol.html