may_nil

Ruby method chaining without worrying about nils

What?

may_nil allows us to write ruby method chains that succinctly handle nil anywhere in the chain.

Within the block passed to may_nil any undefined method on the NilClass termiates the block returning nil. All exceptions other than NoMethodError on NilClass are raised as usual.

Examples

require 'may_nil'

If we have some data...

a = {person: {name: 'Bob',  pet: { likes: ['cat', 'dog', 'mouse'], owns: 'dog' } } }
b = {person: {name: 'Bill', pet: { likes: ['cat', 'dog', 'mouse'] } } }
c = {person: {name: 'Brian' } }
d = nil

def owns_pet( data )
  may_nil {data[:person][:pet][:owns]}
end

owns_pet(a)   => 'dog'
owns_pet(b)   =>  nil
owns_pet(c)   =>  nil
owns_pet(d)   =>  nil

Or a method chain...

nil.foo.bar[2].baz             => Exception: NoMethodError (foo on NilClass)
may_nil {nil.foo.bar[2].baz}   => nil
may_nil {100.foo.bar[2].baz}   => Exception: NoMethodError (foo on Fixnum)

class Fixnum
  def foo(v) 
    v+1
  end
  def bar(v)
    [v]
  end
  def baz(v)
    v.to_s
  end
end
may_nil {1.foo.bar[0].baz}    => "2"
may_nil {1.foo.bar[1].baz}    => nil

Installing

Gemfile

gem 'may_nil', :git => 'https://github.com/meesern/may_nil.git'

Why?

may_nil is similar in purpose to the andand gem (https://github.com/raganwald/andand) but removes the need to fill the method chain with .andand...

nil.andand.foo.bar            => Exception: NoMethodError (bar on NilClass)
nil && nil.foo && nil.foo.bar => nil
nil.andand.foo.andand.bar     => nil
may_nil {nil.foo.bar}         => nil

meesern / may_nil