Rails - Dec 2010 - Is apostrophe (') something special in a regex if at end?

(Ruby 1.9.2) I have a simple validation regex which I need to pass the
following values: "Billy-Bob" and "O''Kelley" (as
test cases). Originally I
was not allowing apostrophe but it became apparent I had to allow it.

The initial regex was:

/^[a-zA-Z -]*$/

Now, when I added the apostrophe like this:

/^[a-zA-Z'' -'']*$/

Then for some reason "Billy-Bob" was not getting matched:
> "Billy-Bob" =~ /^[a-zA-Z -'']*$/
> nil
> "O''Kelley" =~ /^[a-zA-Z'' -'']*$/
> 0
But when I moved the apostrophe further in, then things work as desired an
expected:
> "Billy-Bob" =~ /^[a-zA-Z'' -]*$/
> 0
> "O''Kelley" =~ /^[a-zA-Z'' -]*$/
> 0
Why is this?

-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.

On 27 December 2010 16:42, David Kahn
<dk-rfEMNHKVqOwNic7Bib+Ti1W1rNmOCjRP@public.gmane.org>
wrote:
> (Ruby 1.9.2) I have a simple validation regex which I need to pass the
> following values: "Billy-Bob" and "O''Kelley"
(as test cases). Originally I
> was not allowing apostrophe but it became apparent I had to allow it.
>
> The initial regex was:
>
> /^[a-zA-Z -]*$/
>
> Now, when I added the apostrophe like this:
>
> /^[a-zA-Z'' -'']*$/
>
> Then for some reason "Billy-Bob" was not getting matched:
>
>> "Billy-Bob" =~ /^[a-zA-Z -'']*$/
>> nil
>> "O''Kelley" =~ /^[a-zA-Z'' -'']*$/
>> 0
>
> But when I moved the apostrophe further in, then things work as desired an
> expected:
>
>> "Billy-Bob" =~ /^[a-zA-Z'' -]*$/
>> 0
>> "O''Kelley" =~ /^[a-zA-Z'' -]*$/
>> 0
>
> Why is this?
It is the minus that is a special char (as in a-z) if you escape the
minus it is ok.
ruby-1.9.2-p0 > "Billy-Bob" =~ /^[a-zA-Z \-'']*$/
 => 0
ruby-1.9.2-p0 > "O''Kelley" =~ /^[a-zA-Z \-'']*$/
=> 0

Colin
>
> --
> You received this message because you are subscribed to the Google Groups
> "Ruby on Rails: Talk" group.
> To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> To unsubscribe from this group, send email to
>
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> For more options, visit this group at
> http://groups.google.com/group/rubyonrails-talk?hl=en.
>
-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.

On Mon, Dec 27, 2010 at 10:52 AM, Colin Law
<clanlaw-gM/Ye1E23mwN+BqQ9rBEUg@public.gmane.org> wrote:
> On 27 December 2010 16:42, David Kahn
<dk-rfEMNHKVqOwNic7Bib+Ti1W1rNmOCjRP@public.gmane.org> wrote:
> > (Ruby 1.9.2) I have a simple validation regex which I need to pass the
> > following values: "Billy-Bob" and
"O''Kelley" (as test cases). Originally
> I
> > was not allowing apostrophe but it became apparent I had to allow it.
> >
> > The initial regex was:
> >
> > /^[a-zA-Z -]*$/
> >
> > Now, when I added the apostrophe like this:
> >
> > /^[a-zA-Z'' -'']*$/
> >
> > Then for some reason "Billy-Bob" was not getting matched:
> >
> >> "Billy-Bob" =~ /^[a-zA-Z -'']*$/
> >> nil
> >> "O''Kelley" =~ /^[a-zA-Z''
-'']*$/
> >> 0
> >
> > But when I moved the apostrophe further in, then things work as
desired
> an
> > expected:
> >
> >> "Billy-Bob" =~ /^[a-zA-Z'' -]*$/
> >> 0
> >> "O''Kelley" =~ /^[a-zA-Z'' -]*$/
> >> 0
> >
> > Why is this?
>
> It is the minus that is a special char (as in a-z) if you escape the
> minus it is ok.
>
Yes I see you are right ---the weird part is that the minus is getting
passed not as a special character in the first examples ( "Billy-Bob"
=~
/^[a-zA-Z'' -]*$/ returns 0!) .... anyhow, I will remember than and
start
escaping it.

> ruby-1.9.2-p0 > "Billy-Bob" =~ /^[a-zA-Z \-'']*$/
>  => 0
> ruby-1.9.2-p0 > "O''Kelley" =~ /^[a-zA-Z
\-'']*$/
> => 0
>
> Colin
> >
> > --
> > You received this message because you are subscribed to the Google
Groups
> > "Ruby on Rails: Talk" group.
> > To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> > To unsubscribe from this group, send email to
> >
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org<rubyonrails-talk%2Bunsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org>
> .
> > For more options, visit this group at
> > http://groups.google.com/group/rubyonrails-talk?hl=en.
> >
>
> --
> You received this message because you are subscribed to the Google Groups
> "Ruby on Rails: Talk" group.
> To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> To unsubscribe from this group, send email to
>
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org<rubyonrails-talk%2Bunsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org>
> .
> For more options, visit this group at
> http://groups.google.com/group/rubyonrails-talk?hl=en.
>
>
-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.

On 27 December 2010 16:59, David Kahn
<dk-rfEMNHKVqOwNic7Bib+Ti1W1rNmOCjRP@public.gmane.org>
wrote:
>> ...
>> It is the minus that is a special char (as in a-z) if you escape the
>> minus it is ok.
>
> Yes I see you are right ---the weird part is that the minus is getting
> passed not as a special character in the first examples (
"Billy-Bob" =~
> /^[a-zA-Z'' -]*$/ returns 0!) .... anyhow, I will remember than and
start
> escaping it.
Yes I wondered about that.  Either it is a bug or a documented feature
that - does not need to be escaped in some circumstances.  Or perhaps
[a-zA-Z -] means something that neither of us understands.

Colin

-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.

On Dec 27, 2010, at 11:59 AM, David Kahn wrote:
> It is the minus that is a special char (as in a-z) if you escape the
> minus it is ok.
>
> Yes I see you are right ---the weird part is that the minus is  
> getting passed not as a special character in the first examples  
> ( "Billy-Bob" =~ /^[a-zA-Z'' -]*$/ returns 0!) ....
anyhow, I will
> remember than and start escaping it.

The minus (hyphen) in a charset is un-special if it is at the  
beginning or the end. You''re better off escaping it yourself for  
exactly the reason you encountered – adding another character to the  
end changed the meaning of the regular expression (charset) in a way  
you didn''t expect.

-Rob

Rob Biedenharn		
Rob-xa9cJyRlE0mWcWVYNo9pwxS2lgjeYSpx@public.gmane.org
http://AgileConsultingLLC.com/
rab-/VpnD74mH8+00s0LW7PaslaTQe2KTcn/@public.gmane.org	
http://GaslightSoftware.com/

-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.

On Mon, Dec 27, 2010 at 11:07 AM, Rob Biedenharn
<Rob-GBZH0y1GwQfnZcttdmLDtYVOj8xgHMYO@public.gmane.orgm
> wrote:
>
> On Dec 27, 2010, at 11:59 AM, David Kahn wrote:
>
> It is the minus that is a special char (as in a-z) if you escape the
>> minus it is ok.
>>
>
> Yes I see you are right ---the weird part is that the minus is getting
> passed not as a special character in the first examples (
"Billy-Bob" =~
> /^[a-zA-Z'' -]*$/ returns 0!) .... anyhow, I will remember than and
start
> escaping it.
>
>
> The minus (hyphen) in a charset is un-special if it is at the beginning or
> the end. You''re better off escaping it yourself for exactly the
reason you
> encountered – adding another character to the end changed the meaning of
the
> regular expression (charset) in a way you didn''t expect.
>
Makes sense, thanks

>
> -Rob
>
> Rob Biedenharn
> Rob-xa9cJyRlE0mWcWVYNo9pwxS2lgjeYSpx@public.gmane.org
http://AgileConsultingLLC.com/
> rab-/VpnD74mH8+00s0LW7PaslaTQe2KTcn/@public.gmane.org
<Rob-/VpnD74mH8+00s0LW7PaslaTQe2KTcn/@public.gmane.org>
> http://GaslightSoftware.com/
>
>  --
> You received this message because you are subscribed to the Google Groups
> "Ruby on Rails: Talk" group.
> To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> To unsubscribe from this group, send email to
>
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org<rubyonrails-talk%2Bunsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org>
> .
> For more options, visit this group at
> http://groups.google.com/group/rubyonrails-talk?hl=en.
>
-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.