From: Josh Cheek <josh.cheek@...>
Date: 2013-03-31T07:26:41+09:00
Subject: Re: Grasping methods like "to_s"?

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On Sat, Mar 30, 2013 at 4:49 PM, Rafal C. <lists@ruby-forum.com> wrote:

> Hi, I'm posting here to quickly ask you: how is one able to do something
> like:
>
>     "string".is_i?
>
> ...where "is_i?" is a method I created, on any object? This kind of goes
> into monkey-patching I guess. Would I have to do:
>
>     class String
>       # My method
>     end
>
> ...for every class I want that method to be available upon? So what if I
> want a method called "is_i?" to be available for the String, Integer,
> and Hash classes? Would I have to add that method to each of the classes
> separately (like above)?
>
> Thanks, and I apologise for the, some say, n00b'iness of this question.
>
>
Since all the classes you would want to put it on inherit from Object, you
would define it on Object

class Object
  def is_i?
    false
  end
end

class Integer
  def is_i?
    true
  end
end

"abc".is_i? # => false
123.is_i?   # => true


With that said, I'm going to recommend not doing this in any code you
intend to maintain or distribute as a library, because it affects the
environment.

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On Sat, Mar 30, 2013 at 4:49 PM, Rafal C. <span dir=3D"ltr">&lt;<a href=3D"=
mailto:lists@ruby-forum.com" target=3D"_blank">lists@ruby-forum.com</a>&gt;=
</span> wrote:<br><div class=3D"gmail_quote"><blockquote class=3D"gmail_quo=
te" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"=
>
Hi, I&#39;m posting here to quickly ask you: how is one able to do somethin=
g<br>
like:<br>
<br>
=A0 =A0 &quot;string&quot;.is_i?<br>
<br>
...where &quot;is_i?&quot; is a method I created, on any object? This kind =
of goes<br>
into monkey-patching I guess. Would I have to do:<br>
<br>
=A0 =A0 class String<br>
=A0 =A0 =A0 # My method<br>
=A0 =A0 end<br>
<br>
...for every class I want that method to be available upon? So what if I<br=
>
want a method called &quot;is_i?&quot; to be available for the String, Inte=
ger,<br>
and Hash classes? Would I have to add that method to each of the classes<br=
>
separately (like above)?<br>
<br>
Thanks, and I apologise for the, some say, n00b&#39;iness of this question.=
<br>
<span class=3D"HOEnZb"><font color=3D"#888888"><br></font></span></blockquo=
te><div><br></div><div>Since all the classes you would want to put it on in=
herit from Object, you would define it on Object</div><div><br></div><div>
<div>class Object</div><div>=A0 def is_i?</div><div>=A0 =A0 false</div><div=
>=A0 end</div><div>end</div><div><br></div><div>class Integer</div><div>=A0=
 def is_i?</div><div>=A0 =A0 true</div><div>=A0 end</div><div>end</div><div=
><br></div><div>
&quot;abc&quot;.is_i? # =3D&gt; false</div><div>123.is_i? =A0 # =3D&gt; tru=
e</div></div><div><br></div><div><br></div><div>With that said, I&#39;m goi=
ng to recommend not doing this in any code you intend to maintain or distri=
bute as a library, because it affects the environment.</div>
</div>

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