ruby – How to return nil or false when the argument of File.exist? is nil

Question: Question:

If there is a possibility that the argument is nil when checking the existence of the file with File.exist?

File.exist?(filename) if filename

If the filename is nil , it returns nil , and if it is a String , is there a standard way to write File.exist? a form similar to try ?

If I need to define the method myself, I'm thinking of keeping the current writing style, but if there is a better writing style, I'd like to ask a question.

I'm thinking of adopting a form that reads all usable methods such as active_support .

Answer: Answer:

I don't know how to write the standard,


If so, the existence check can be executed regardless of whether the filename is nil or String .

> File.exists?(nil)
TypeError: no implicit conversion of nil into String
    from (irb):1:in `exists?'
    from (irb):1
    from /Users/jit/.rbenv/versions/2.2.0/bin/irb:11:in `<main>'
> File.exists?(nil.to_s)
=> false

By the way, if you want to distinguish between true / false / nil and return it, it is difficult to give an appropriate answer unless you include the background. (Maybe you're trying to do something special)

Normally, both false / nil are treated as false, so I think it is a rare case to distinguish them.

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