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require 'monadic'
Person = Struct.new(:name, :age)
module PersonValidation
class AgeTooLowError < ArgumentError; end
class AgeTooHighError < ArgumentError; end
def self.validate(params)
Validation() do
extend PersonValidation
check { valid_age(params[:age]) }
check { valid_name(params[:name])}
end
end
def valid_age(expr)
age = expr.to_i
case
when expr.nil?; Failure(ArgumentError.new(:age))
when age <= 0; Failure(AgeTooLowError.new(expr))
when age > 130; Failure(AgeTooHighError.new(expr))
else Success(age)
end
end
def valid_name(name)
case
when name =~ /\w{3,99}/i; Success(name)
else Failure('Invalid name')
end
end
end
module PersonBuild
def self.build(params)
result = PersonValidation.validate(params)
case result
when Failure; result
when Success; Person.new(*result.fetch)
end
end
end
p person1 = PersonBuild.build({ name: 'Andrzej' }) # Failure([#<ArgumentError: age>])
p person2 = PersonBuild.build({ name: 'Andrzej', age: 32 }) # <struct Person name=32, age="Andrzej">
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