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Comment by enko | Hacker News Reader

This series is invaluable. I have been programming in Ruby professionally for over 7 years and did not know about Array()! Since then I have been joyfully combing through my repos and eliminating literally dozens of

  obj = [obj] unless obj.type_of?(Array)

Integer() was another head-slapper that I can't believe I didn't know. And the series is full of them.

Thanks very much to the Author(s)!

  TypeError: can't convert nil into Author

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Be careful with Array() since it uses #to_a method whenever it exists. As such, this trick is unsuitable for array of hashes (in any version of ruby) and strings (in ruby 1.8).

Other Enumerables might make for unpleasant surprise too.

Old mootools had $A method (called Array.from now) which did exactly what you expected.

If you already use ActiveSupport, then you can use Array#wrap http://api.rubyonrails.org/classes/Array.html#method-c-wrap

This is exactly what I meant! Thank you!

The author is my colleague Mat - https://news.ycombinator.com/user?id=matsadler

He's one of those quiet geniuses that we feel exceptionally lucky to have as part of our team.

Integer() or Float() let you do cool things like this:

    def is_int?(x)
      Integer(x); true; rescue; false
    end

Which will let you know if some input passed can be safely converted to an integer.

A couple of minor nits:

- is_int? is rather misleading (I would not expect is_int?(1.2) to be true)

- Since Ruby ints are truthy, the idiomatic form would probably just return Integer(x) and false or nil otherwise:

    def is_int?(x)
      Integer(x) rescue false
    end

s/is_int/intable/ ;-)

Ah you're right. Hadn't actually tested this. The way that I've actually used it is for `is_num?` and using `Float()`. I didn't consider the fact that `Integer` would cast a float.

Most if not all of this is in the language documentation. It's the best source, along with the actual implementation for learning this stuff. A good way to learn is to try to read docs for one module a day.

Doing open source, you learn little nuggets like this. I learned about `Array()` when checking out how Rails routing allowed you to pass a symbol or an array, like:

    resources :photos, only: [:index, :show]

    resources :photos, only: :show

For those interested, this is the relevant code: https://github.com/rails/rails/blob/master/actionpack/lib/ac...

I too was unaware of Array(), what an awesome little function! Definitely gonna read this series from the beginning.

Another invaluable resource is 'Ruby Best Practices' by Gregory Brown. You can download the pdf for free (http://majesticseacreature.com/rbp-book/pdfs/rbp_1-0.pdf).

I've always seen the idiom [*array_or_object] used to do that. Array() is definitely clearer though.

This works well for us:

   obj = [obj].flatten

BTW, enko is referring to Part 2: http://globaldev.co.uk/2013/09/ruby-tips-part-2/

And I agree...I've been programming in Ruby for awhile and only lately had learned about the `Array()` conversion, which I learned through Avdi Grimm's "Confident Ruby" book (he blogged about Array several years ago: http://devblog.avdi.org/2009/10/21/array-ifying-values/).

Such a small thing, but as you note, can greatly impact the cruft in your error-checking interfaces.

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