# Syntax error in Ruby Cookbook example

**URL:** <https://www.ruby-forum.com/t/syntax-error-in-ruby-cookbook-example/170393>\
**Category:** Ruby\
**Created:** [June 17, 2009, 12:00am UTC](https://www.ruby-forum.com/t/syntax-error-in-ruby-cookbook-example/170393 "2009-06-17T00:00:38Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![JSU](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/73ab20/32.png) [@JSU](https://www.ruby-forum.com/u/JSU)\
**Post date:** [June 17, 2009, 12:00am UTC](https://www.ruby-forum.com/t/syntax-error-in-ruby-cookbook-example/170393/1 "2009-06-17T00:00:38Z")

</div>

I am practicing/learning Ruby using Study Notes from [www.ruby-lang.org](http://www.ruby-lang.org).  
I am working on Validation program taken from Ruby Cookbook, but  
unable to run program as is. Please advise where I may have gone  
wrong.  
Thanks in advance. JSU

# p050inputvalidation.rb

# Here’s an example from the Ruby Cookbook,

# showing how one can do validation of user’s inputs.

class Name

# Define default getter methods, but not setter methods.

attr\_reader :first, :last

# When someone tries to set a first name,

# enforce rules about it.

def first=(first)  
if (first == nil or first.size == 0)  
raise ArgumentError.new(‘Everyone must have a first name.’)  
end  
first = first.dup  
first[0] = first[0].chr.capitalize  
@first = first  
end

# When someone tries to set a last name,

```
 # enforce rules about it.

```

def last=(last)  
if (last == nil || last.size == 0)  
raise ArgumentError.new(‘Everyone must have a last name.’)  
end  
last[0] = last[0].chr.capitalize  
@last = last  
end

def full\_name  
“#{@first} #{@last}”  
end

# Delegate to the setter methods instead of

```
 # setting the instance variables directly.

```

def initialize(first, last)  
self.first = first  
self.last = last  
end  
end

jacob = Name.new(‘Jacob’, ‘Berendes’)  
jacob.first = ‘Mary Sue’  
jacob.full\_name # =\> “Mary Sue Berendes”  
john = Name.new(‘John’, ‘Von Neumann’)  
john.full\_name # “John Von Neumann”  
john.first = ‘john’  
john.first # =\> “john”  
john.first = nil

# ArgumentError: Everyone must have a first name.

Name.new(‘Kero, international football star and performance artist’,  
nil)

# ArgumentError: Everyone must have a last name.

And my output is as follows:

> ruby p050inputvalidation.rb  
> p050inputvalidation.rb:11:in `first=': Everyone must have a first  
> name. (ArgumentError)  
> from p050inputvalidation.rb:46  
> Exit code: 1

Thanks again!

---

<div class="post-metadata">

**Author:** ![JSU](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/73ab20/32.png) [@JSU](https://www.ruby-forum.com/u/JSU)\
**Post date:** [June 17, 2009, 1:31am UTC](https://www.ruby-forum.com/t/syntax-error-in-ruby-cookbook-example/170393/2 "2009-06-17T01:31:20Z")

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Am Mittwoch 17 Juni 2009 00:00:05 schrieb JSU:

> I am working on Validation program taken from Ruby Cookbook, but  
> unable to run program as is.

From what you’ve pasted it seems like you’re getting exactly the result  
that  
the comments indicate you should be getting, so I don’t see a problem  
there.  
If you look at the comments, you’ll notice that some of those lines are  
supposed to cause Exceptions.

HTH,  
Sebastian

---

<div class="post-metadata">

**Author:** ![JSU](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/73ab20/32.png) [@JSU](https://www.ruby-forum.com/u/JSU)\
**Post date:** [June 17, 2009, 6:45am UTC](https://www.ruby-forum.com/t/syntax-error-in-ruby-cookbook-example/170393/3 "2009-06-17T06:45:58Z")

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On Jun 16, 4:30 pm, Sebastian H. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)  
wrote:

> HTH,  
> Sebastian

Thanks Sebastian. I suppose I was thrown because it doesn’t look all  
tidy like the other examples. Cheers. JSU