Nil Slides - Code Like This

Nil

nil is a magic object

nil is the object that means "there is no object"

Q: What is the sound of one hand clapping?

A: nil

fruit = "apple"
fruit = nil
fruit.reverse

Read the error!

They tell you

Interpret this error:

fruit.reverse
NoMethodError: undefined method `reverse' for nil:NilClass

null pointer errors are very common
the trick is reading the error and figuring out
1. where it happened (*which line*)
2. which variable was null
often once you know which, knowing why is obvious
or at least tracing back the logic is possible

Two philosophies:

Which idea is better?

Why or why not?

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