What you learned about symbols

Precautions for creating symbols

How to write with an error


#Error occurs if you use an invalid string as an identifier (starting with a number, including hyphens, spaces)
:5678             #=>SyntaxError
:rails-is-easy    #=>Nameerror
:rails is easy    #=>SyntaxError
:()               #=>SyntaxError

#Effective as a symbol when surrounded by a single quote
:'5678'           #=>"5678"
:'rails-is-easy'  #=>"rails-is-easy"
:'rails is easy'  #=>"rails is easy"
:'()'             #=>"()"

Expression expansion in a symbol


#Use double quotes
title = 'Taro'
:"#{title.upcase}" #=> :TARO

Symbols and strings

Strings and symbols are different, so they are not compatible. However, there are methods that convert strings to symbols and methods that convert symbols to strings.

python


string = 'ruby'
sypbol = :ruby
string == symbol #=> false

#to_sym method:Convert strings to symbols
string.to_sym           #=> :ruby 
string.to_sym == symbol #=> true

#to_s method:Convert symbols to strings
symbol.to_s           #=> "ruby" 
symbol.to_s == string #=> true  

References An introduction to Ruby for those who want to become professionals

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