From: Navindra Umanee <navindra@...>
Date: 2012-01-28T08:40:00+09:00
Subject: Why is a = a nil instead of giving NameError

Could someone help me understand what is happening here?

irb(main):001:0> a
NameError: undefined local variable or method `a' for main:Object
        from (irb):1
irb(main):002:0> b
NameError: undefined local variable or method `b' for main:Object
        from (irb):2
irb(main):003:0> c
NameError: undefined local variable or method `c' for main:Object
        from (irb):3
irb(main):004:0> b = c
NameError: undefined local variable or method `c' for main:Object
        from (irb):4
        from :0
irb(main):005:0> a = a
=> nil

a is undefined, so why does "a = a" work instead of giving a NameError
like "b = c" does?

Also:

irb(main):006:0> b = c
NameError: undefined local variable or method `c' for main:Object
        from (irb):6
        from :0
irb(main):007:0> b
=> nil

Why did b get initialized to nil if there was a NameError?

Source:

https://www.destroyallsoftware.com/talks/wat

Thanks!
Navin.

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