De-camelcase a filename

ruby-talk
1

how can a take a string file name like MyTestCase.rb and change it to
my_test_case.rb?

thanks

···

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2

I'm a novice at Ruby, but this might help:

irb(main):013:0> 'MyTestCase'.gsub(/[A-Z]/) {
irb(main):014:1* |p| '_' + p.downcase
irb(main):015:1> }
=> "_my_test_case"

then:

irb(main):020:0> "_my_test_case"[1..-1]
=> "my_test_case"

Veterans can provide more succinct ways though :slight_smile:

Cheers,
Swaroop

···

On 6/30/07, Aaron Smith <beingthexemplary@gmail.com> wrote:

how can a take a string file name like MyTestCase.rb and change it to
my_test_case.rb?

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3

Aaron Smith wrote:

how can a take a string file name like MyTestCase.rb and change it to
my_test_case.rb?

thanks

Possibly overkill, but you can use ActiveSupport, it has this
functionality built in:

irb(main):001:0> require 'rubygems'
=> true
irb(main):002:0> require 'active_support'
=> true
irb(main):003:0> "ThisIsATest".underscore
=> "this_is_a_test"

···

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4

Veterans can provide more succinct ways though :slight_smile:

I wouldn't consider myself a veteran yet, but here's how Rails does it:

camel_cased_word.to_s.gsub(/::/, '/').
      gsub(/([A-Z]+)([A-Z][a-z])/,'\1_\2').
      gsub(/([a-z\d])([A-Z])/,'\1_\2').
      tr("-", "_").
      downcase

That also changes :: to /, so it's handy for translating a module name to a file path. It's not exactly more succinct, but you can cut it down as you see fit.

Brett

5

how can a take a string file name like MyTestCase.rb and change it to
my_test_case.rb?

I'm a novice at Ruby, but this might help:

irb(main):013:0> 'MyTestCase'.gsub(/[A-Z]/) {
irb(main):014:1* |p| '_' + p.downcase
irb(main):015:1> }
=> "_my_test_case"

then:

irb(main):020:0> "_my_test_case"[1..-1]
=> "my_test_case"

Here's another way:

irb(main):078:0> "FooBarBaz".split(/(?=[A-Z])/).map{|w| w.downcase}.join("_")
=> "foo_bar_baz"

Regards,

Bill

···

From: "Swaroop C H" <swaroopch@gmail.com>

On 6/30/07, Aaron Smith <beingthexemplary@gmail.com> wrote:

6

Just be careful of any code that has dependencies on the camelCaps version!
You might even write a conditional require statement to check for both versions.

···

On Jun 30, 2007, at 3:17 PM, Bill Kelly wrote:

From: "Swaroop C H" <swaroopch@gmail.com>

On 6/30/07, Aaron Smith <beingthexemplary@gmail.com> wrote:

how can a take a string file name like MyTestCase.rb and change it to
my_test_case.rb?

I'm a novice at Ruby, but this might help:
irb(main):013:0> 'MyTestCase'.gsub(/[A-Z]/) {
irb(main):014:1* |p| '_' + p.downcase
irb(main):015:1> }
=> "_my_test_case"
then:
irb(main):020:0> "_my_test_case"[1..-1]
=> "my_test_case"

Here's another way:

irb(main):078:0> "FooBarBaz".split(/(?=[A-Z])/).map{|w| w.downcase}.join("_")
=> "foo_bar_baz"

Regards,

Bill

7

After seeing this split -> map -> join in my scripts, I came up with smj:

class String
    def smj(s, j=s, &b)
        r = self.split(s).map(&b)
        j ? r.join(j) : r
    end
end

So the above would become:
"FooBarBaz".smj(/(?=[A-Z])/, '_') { |w| w.downcase } #=> "foo_bar_baz"

I love Pe...Ruby! I love Ruby!

-Ben Kudria

···

On Saturday, June 30 2007, Bill Kelly wrote:

From: "Swaroop C H" <swaroopch@gmail.com>

> On 6/30/07, Aaron Smith <beingthexemplary@gmail.com> wrote:
>> how can a take a string file name like MyTestCase.rb and change it to
>> my_test_case.rb?
>
> I'm a novice at Ruby, but this might help:
>
> irb(main):013:0> 'MyTestCase'.gsub(/[A-Z]/) {
> irb(main):014:1* |p| '_' + p.downcase
> irb(main):015:1> }
> => "_my_test_case"
>
> then:
>
> irb(main):020:0> "_my_test_case"[1..-1]
> => "my_test_case"

Here's another way:

irb(main):078:0> "FooBarBaz".split(/(?=[A-Z])/).map{|w|
w.downcase}.join("_") => "foo_bar_baz"

8

John Joyce wrote:

···

On Jun 30, 2007, at 3:17 PM, Bill Kelly wrote:

=> "_my_test_case"

Regards,

Bill

Just be careful of any code that has dependencies on the camelCaps
version!
You might even write a conditional require statement to check for
both versions.

Thanks everyone!

--
Posted via http://www.ruby-forum.com/\.

9

How about this:
"FooBarBaz".split(/(?=[A-Z])/).join('_').downcase

···

--
Posted via http://www.ruby-forum.com/.

10

How about this:
"FooBarBaz".split(/(?=[A-Z])/).join('_').downcase

Nice... (why didn't I think of that :slight_smile:

Regards,

Bill

···

From: "Roseanne Zhang" <roseanne@javaranch.com>

11

This is the cleanest I've come up with:

class String
   # "FooBar".snake_case #=> "foo_bar"
   def snake_case
     gsub(/\B[A-Z]/, '_\&').downcase
   end
end

Cheers-

-- Ezra Zygmuntowicz -- Lead Rails Evangelist
-- ez@engineyard.com
-- Engine Yard, Serious Rails Hosting
-- (866) 518-YARD (9273)

···

On Jul 2, 2007, at 9:41 AM, Bill Kelly wrote:

From: "Roseanne Zhang" <roseanne@javaranch.com>

How about this:
"FooBarBaz".split(/(?=[A-Z])/).join('_').downcase

Nice... (why didn't I think of that :slight_smile:

12

Both of these solutions have a problem with back to back caps. For
example:

"CheckHostIP".gsub(/\B[A-Z]/, '_\&').downcase => "check_host_i_p"

But I want "check_host_ip". It's probably a simple tweak, but I'm
having trouble finding it at the moment. Suggestions?

Thanks,

Dan

···

On Jul 2, 11:42 am, Ezra Zygmuntowicz <ezmob...@gmail.com> wrote:

On Jul 2, 2007, at 9:41 AM, Bill Kelly wrote:

> From: "Roseanne Zhang" <rosea...@javaranch.com>
>> How about this:
>> "FooBarBaz".split(/(?=[A-Z])/).join('_').downcase

> Nice... (why didn't I think of that :slight_smile:

This is the cleanest I've come up with:

class String
   # "FooBar".snake_case #=> "foo_bar"
   def snake_case
     gsub(/\B[A-Z]/, '_\&').downcase
   end
end

13

I guess there can be no general solution, I would like
HostIP --> host_ip
but
AHostIP --> a_host_ip

maybe you can use a dictonary of Uppercase Abbreviations as a preparatory step?

Robert

···

On 8/22/07, Daniel Berger <djberg96@gmail.com> wrote:

On Jul 2, 11:42 am, Ezra Zygmuntowicz <ezmob...@gmail.com> wrote:
> On Jul 2, 2007, at 9:41 AM, Bill Kelly wrote:
>
> > From: "Roseanne Zhang" <rosea...@javaranch.com>
> >> How about this:
> >> "FooBarBaz".split(/(?=[A-Z])/).join('_').downcase
>
> > Nice... (why didn't I think of that :slight_smile:
>
> This is the cleanest I've come up with:
>
> class String
> # "FooBar".snake_case #=> "foo_bar"
> def snake_case
> gsub(/\B[A-Z]/, '_\&').downcase
> end
> end

Both of these solutions have a problem with back to back caps. For
example:

"CheckHostIP".gsub(/\B[A-Z]/, '_\&').downcase => "check_host_i_p"

But I want "check_host_ip". It's probably a simple tweak, but I'm
having trouble finding it at the moment. Suggestions?

Thanks,

Dan

--
I'm an atheist and that's it. I believe there's nothing we can know
except that we should be kind to each other and do what we can for
other people.
-- Katharine Hepburn

14

Hi --

From: "Roseanne Zhang" <rosea...@javaranch.com>

How about this:
"FooBarBaz".split(/(?=[A-Z])/).join('_').downcase

Nice... (why didn't I think of that :slight_smile:

This is the cleanest I've come up with:

class String
   # "FooBar".snake_case #=> "foo_bar"
   def snake_case
     gsub(/\B[A-Z]/, '_\&').downcase
   end
end

Both of these solutions have a problem with back to back caps. For
example:

"CheckHostIP".gsub(/\B[A-Z]/, '_\&').downcase => "check_host_i_p"

But I want "check_host_ip". It's probably a simple tweak, but I'm
having trouble finding it at the moment. Suggestions?

Thanks,

Dan

I guess there can be no general solution, I would like
HostIP --> host_ip
but
AHostIP --> a_host_ip

Here's how ActiveSupport does it:

   def underscore(camel_cased_word)
     camel_cased_word.to_s.gsub(/::/, '/').
       gsub(/([A-Z]+)([A-Z][a-z])/,'\1_\2').
       gsub(/([a-z\d])([A-Z])/,'\1_\2').
       tr("-", "_").
       downcase
   end

David

···

On Thu, 23 Aug 2007, Robert Dober wrote:

On 8/22/07, Daniel Berger <djberg96@gmail.com> wrote:

On Jul 2, 11:42 am, Ezra Zygmuntowicz <ezmob...@gmail.com> wrote:

On Jul 2, 2007, at 9:41 AM, Bill Kelly wrote:

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     & consulting: Ruby Power and Light, LLC (http://www.rubypal.com)

15

Sure that is quite clever, but it will e.g. fail on "AMACAddress"
which I want to have as a_mac_address, well but that was a little side
issue of Dan, I guess this is the best solution for OP's problem.
I just wanted to point Dan to the fact that he would need a dictionary.

Cheers

Robert

···

On 8/22/07, David A. Black <dblack@rubypal.com> wrote:

Hi --

On Thu, 23 Aug 2007, Robert Dober wrote:

> On 8/22/07, Daniel Berger <djberg96@gmail.com> wrote:
>> On Jul 2, 11:42 am, Ezra Zygmuntowicz <ezmob...@gmail.com> wrote:
>>> On Jul 2, 2007, at 9:41 AM, Bill Kelly wrote:
>>>
>>>> From: "Roseanne Zhang" <rosea...@javaranch.com>
>>>>> How about this:
>>>>> "FooBarBaz".split(/(?=[A-Z])/).join('_').downcase
>>>
>>>> Nice... (why didn't I think of that :slight_smile:
>>>
>>> This is the cleanest I've come up with:
>>>
>>> class String
>>> # "FooBar".snake_case #=> "foo_bar"
>>> def snake_case
>>> gsub(/\B[A-Z]/, '_\&').downcase
>>> end
>>> end
>>
>> Both of these solutions have a problem with back to back caps. For
>> example:
>>
>> "CheckHostIP".gsub(/\B[A-Z]/, '_\&').downcase => "check_host_i_p"
>>
>> But I want "check_host_ip". It's probably a simple tweak, but I'm
>> having trouble finding it at the moment. Suggestions?
>>
>> Thanks,
>>
>> Dan
>
> I guess there can be no general solution, I would like
> HostIP --> host_ip
> but
> AHostIP --> a_host_ip

Here's how ActiveSupport does it:

   def underscore(camel_cased_word)
     camel_cased_word.to_s.gsub(/::/, '/').
       gsub(/([A-Z]+)([A-Z][a-z])/,'\1_\2').
       gsub(/([a-z\d])([A-Z])/,'\1_\2').
       tr("-", "_").
       downcase
   end

David

--
I'm an atheist and that's it. I believe there's nothing we can know
except that we should be kind to each other and do what we can for
other people.
-- Katharine Hepburn