Ruby Paramater's Default Value

def foobar(a, b='b', c)
 ...
end

foobar(1, 2, 3)
 # a => 1
 # b => 2
 # c => 3

foobar(1, 2)
 # a => 1
 # b => 'b'
 # c => 2


define bar(a, b='b', c='c', d)

bar(1, 2, 3)
 # a => 1
 # b => 2
 # c => 'c'
 # d => 3

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Prefer using default value for parameter from right to left direction

References:

• http://mwrc2008.confreaks.com/04katz.html