# Overload the normal behavior of an object/instance in string

**URL:** <https://www.ruby-forum.com/t/overload-the-normal-behavior-of-an-object-instance-in-string/187745>\
**Category:** Ruby\
**Created:** [April 28, 2010, 7:02pm UTC](https://www.ruby-forum.com/t/overload-the-normal-behavior-of-an-object-instance-in-string/187745 "2010-04-28T19:02:54Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![walle](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/5daacb/32.png) [@walle](https://www.ruby-forum.com/u/walle)\
**Post date:** [April 28, 2010, 7:02pm UTC](https://www.ruby-forum.com/t/overload-the-normal-behavior-of-an-object-instance-in-string/187745/1 "2010-04-28T19:02:54Z")

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Long story short. I’m trying to overload the normal behavior of an  
object/instance in a string. Instead of replying “Test:0x101121db0” I  
would like it too return a specific string, or something similar. I have  
tried to overload inspect, and it seems to work pretty well, except when  
using the object with puts or in a string “#{p}”.

My english ain’t good, but I hope you understand the principle of what I  
am trying to achieve.

```auto
class Test
  def inspect
     puts "this is a test"
  end
end

p = Test.new
this is a test
>> p
this is a test

puts p
#<Test:0x101121db0>

>> "#{p}"
=> "#<Hejsan:0x1010fd7f8>"
```

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<div class="post-metadata">

**Author:** ![walle](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/5daacb/32.png) [@walle](https://www.ruby-forum.com/u/walle)\
**Post date:** [April 28, 2010, 7:24pm UTC](https://www.ruby-forum.com/t/overload-the-normal-behavior-of-an-object-instance-in-string/187745/2 "2010-04-28T19:24:16Z")

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On 28/04/2010 19:03, Walle W. wrote:

> class Test  
> this is a test
> 
> puts p  
> #Test:0x101121db0
> 
> > > “#{p}”
> 
> =\> “#Hejsan:0x1010fd7f8”  
> [/code]

You should return strings from these methods:

class Test  
def inspect  
“this is a test” # return the string, don’t output it  
end

def to\_s  
“this is another test”  
end  
end

Then ruby can call Test#inspect or Test#to\_s as it desires:

p Test.new # outputs: this is a test  
puts Test.new # outputs: this is another test

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<div class="post-metadata">

**Author:** ![walle](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/5daacb/32.png) [@walle](https://www.ruby-forum.com/u/walle)\
**Post date:** [April 28, 2010, 7:27pm UTC](https://www.ruby-forum.com/t/overload-the-normal-behavior-of-an-object-instance-in-string/187745/3 "2010-04-28T19:27:47Z")

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On Wed, Apr 28, 2010 at 1:03 PM, Walle W. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)  
wrote:

> Long story short. I’m trying to overload the normal behavior of an  
> object/instance in a string. Instead of replying “Test:0x101121db0” I  
> would like it too return a specific string, or something similar. I have  
> tried to overload inspect, and it seems to work pretty well, except when  
> using the object with puts or in a string “#{p}”.
> 
> My english ain’t good, but I hope you understand the principle of what I  
> am trying to achieve.

There are two different methods which Ruby uses to get a printstring  
from an object, both of which should return a String.

inspect produces a ‘programmer friendly’ printstring in general, while  
to\_s produces a ‘user friendly’ string.

There’s a Kernel method p which is roughly equvalent to:

def p(arg)  
puts arg.inspect  
end

puts just uses to\_s to convert non-strings to strings.

And irb displays the the value of inspect after evaluating an  
expression.

> [code]  
> class Test  
> def inspect  
> puts “this is a test”  
> end

This should simply return the string, you don’t always want to puts  
the result, and puts will cause the result to be nil, not the string.

> > > “#{p}”  
> > > =\> “#Hejsan:0x1010fd7f8”  
> > > [/code]

Try this:

class Test  
def inspect  
“this is a test inspection”  
end

def to\_s  
“this is a test”  
end  
end

p = Test.new  
puts p  
puts “#{p}”  
puts p.inspect

which produces:

this is a test  
this is a test  
this is a test inspection

–  
Rick DeNatale

Blog: [http://talklikeaduck.denhaven2.com/](http://talklikeaduck.denhaven2.com/)  
Github: [rubyredrick (Rick DeNatale) · GitHub](http://github.com/rubyredrick)  
Twitter: @RickDeNatale  
WWR: [http://www.workingwithrails.com/person/9021-rick-denatale](http://www.workingwithrails.com/person/9021-rick-denatale)  
LinkedIn: [http://www.linkedin.com/in/rickdenatale](http://www.linkedin.com/in/rickdenatale)

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<div class="post-metadata">

**Author:** ![walle](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/5daacb/32.png) [@walle](https://www.ruby-forum.com/u/walle)\
**Post date:** [April 28, 2010, 7:31pm UTC](https://www.ruby-forum.com/t/overload-the-normal-behavior-of-an-object-instance-in-string/187745/4 "2010-04-28T19:31:09Z")

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Florian F. wrote:

> On 28/04/2010 19:03, Walle W. wrote:  
> You should return strings from these methods:  
> ah…yea… I mistyped the example 🙂

Thanks to you both. Works like charm 🙂