From: Chad Perrin <code@...>
Date: 2011-10-19T03:15:27+09:00
Subject: Re: Return

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On Wed, Oct 19, 2011 at 02:26:54AM +0900, Junayeed Ahnaf Nirjhor wrote:
>=20
> What does return do? I mean, it returns something, then why does it vary =
from puts?

    (1+1)

That expression returns a value of 2.

    foo =3D (1+1)

That captures the return value of 2 in a variable called foo.

    puts (1+1)

That prints the return value of 2 as a string to standard output, and
adds a newline to the end of it.

    foo =3D (1+1)

That, too, is an expression with a return value.  The return value
happens to be the same value captured in the variable foo, so once again
the return value of 2 applies.

    puts (1+1)

The puts method has a return value of nil, so that expression returns a
value of nil.

    foo =3D puts (1+1)

Here, the nil return value of the puts method is captured in the foo
variable, which then returns a value of nil.

If you use irb, it looks a bit like this:

    $ irb
    >> (1+1)
    =3D> 2
    >> foo =3D (1+1)
    =3D> 2
    >> puts (1+1)
    2
    =3D> nil
    >> foo =3D puts (1+1)
    2
    =3D> nil

Those lines that start with >> are the prompts where I entered Ruby
expressions.

The lines that start with =3D> show the return values of those expressions
when they are executed.

The lines that show nothing but 2 are the lines that show what puts sends
to standard output.

Here's a little more irb experimentation on the subject:

    >> puts puts (1+1)
    2

    =3D> nil
    >> puts (puts (1+1)).inspect
    2
    nil
    =3D> nil

I hope that helps.

--=20
Chad Perrin [ original content licensed OWL: http://owl.apotheon.org ]

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