From: Matthew Kerwin <matthew@...>
Date: 2013-03-12T15:39:56+09:00
Subject: Re: Confusion with empty block printing

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Stop using irb. Write a .rb file and run it. Then you will (hopefully) see
that:

1. print needs a "\n" to push output to the next line

    print 'h'
    print 'i'
    print "p\ncat"

2. anything that starts with"#=>" isn't _real_ output; it's stuff irb does

    x = 3  # no output

2b) those things are the _VALUE OF THE PREVIOUS EXPRESSION_

    puts '#=> ' + x.inspect

3. `print` has a _value_ of nil

    x = print('')  # x is now nil
    puts '#=> ' + x.inspect  # see?

3b) `foo.class` has a value of the object that foo is a new one of

    foo = Object.new
    foo2 = foo.class.new

4. these are the same:

    print {}

    print do
    end

4b) print {}  outputs nothing, and still has a value of nil
4c) nil.class has a value of NilClass

Sent from my phone, so excuse the typos.

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<p>Stop using irb. Write a .rb file and run it. Then you will (hopefully) s=
ee that:</p>
<p>1. print needs a &quot;\n&quot; to push output to the next line</p>
<p>=A0=A0=A0 print &#39;h&#39;<br>
=A0=A0=A0 print &#39;i&#39;<br>
=A0=A0=A0 print &quot;p\ncat&quot;</p>
<p>2. anything that starts with&quot;#=3D&gt;&quot; isn&#39;t _real_ output=
; it&#39;s stuff irb does</p>
<p>=A0=A0=A0 x =3D 3=A0 # no output</p>
<p>2b) those things are the _VALUE OF THE PREVIOUS EXPRESSION_</p>
<p>=A0=A0=A0 puts &#39;#=3D&gt; &#39; + x.inspect</p>
<p>3. `print` has a _value_ of nil</p>
<p>=A0=A0=A0 x =3D print(&#39;&#39;)=A0 # x is now nil<br>
=A0=A0=A0 puts &#39;#=3D&gt; &#39; + x.inspect=A0 # see?</p>
<p>3b) `foo.class` has a value of the object that foo is a new one of</p>
<p>=A0=A0=A0 foo =3D Object.new<br>
=A0=A0=A0 foo2 =3D foo.class.new</p>
<p>4. these are the same:</p>
<p>=A0=A0=A0 print {}<br>
=A0=A0=A0 <br>
=A0=A0=A0 print do<br>
=A0=A0=A0 end</p>
<p>4b) print {}=A0 outputs nothing, and still has a value of nil<br>
4c) nil.class has a value of NilClass</p>
<p>Sent from my phone, so excuse the typos.</p>

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