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Ruby Ruby Foundations Procs & Lambdas Creating Procs & Lambdas

Posted by Alex Bishop
Alex Bishop
4,817 Points

Can I get a quick refresher on the .call method?

I most likely have this in my notes somewhere but it has been awhile and I would like some help. I want to know what exactly the .call command does in respect to calling code such as a proc or lambda. I went to the ruby doc and got the following as an answer:

call(params,...) → obj Invokes the block, setting the block’s parameters to the values in params using something close to method calling semantics. Generates a warning if multiple values are passed to a proc that expects just one (previously this silently converted the parameters to an array). Note that prc.() invokes prc.call() with the parameters given. It’s a syntax sugar to hide “call”.

So does .call just run the code and output the values if used? Is there a simpler way to put this, or am I wrong here? I would like this in laymen's terms and explained simply if possible.

Thanks ahead of time for any help I get!

1 Answer

Ronald Jackson
Ronald Jackson
9,229 Points

Hi Alex -

I'll explain what the call method does by giving an example of how it works.

Let's say I write the following code:

division = Proc.new{|n| n / n}
division.call(12)

Running this code will return 1. When I invoke my proc's call method with the parameter 12, it causes the code in the block {|n| n / n} to run.

That's how the call method works with a proc. The explanation in ruby doc says what I've ilustrated in this example, but with much "bigger" words.

Hope this helps!

Best,

Ronald

Alex Bishop
Alex Bishop
4,817 Points

Thanks Ronald, I just needed to see it in code, I get of the just of it now.