Comments on: Substrings in Ruby

By: Pistos

Pistos — Wed, 10 Jun 2009 13:07:43 +0000

Ruby 1.9 has named captures. With this we can name capture groups in a regexp, and then local variables are assigned the captured strings.

s = "a123 bxyz"
/a(?<my_a>\S+) +b(?<my_b>\S+)/ =~ s
my_a #=> "123"
my_b #=> "xyz"

By: Pistos

Pistos — Mon, 04 Jun 2007 16:53:23 +0000

Oh, I see. Well… I guess we need to use

and preview.

By: manveru

manveru — Mon, 04 Jun 2007 16:16:12 +0000

Yes, but it still tries to remove the \

By: Pistos

Pistos — Mon, 04 Jun 2007 15:38:34 +0000

Hrm:

  test code
  right here.

Seems to work for me? The way I'm getting the highlighted code blocks is actually via the syntax highlight Wordpress plugin. Add code blocks on my blog with

By: manveru

manveru — Mon, 04 Jun 2007 15:11:04 +0000

Yeah, i noticed that but didn't want to double-post. To parse something like this i would use:

  string = 'Monday, June 4, 2007'
  format = '%A, %B %d, %Y'
  date = Date.strptime(string, format)
  puts date
  # => 2007-06-04

But i get your point, groups would be quite handy at times instead of:

  'Monday, June 4, 2007'.match(/^(\\w+), (\\w+) (\\d+), (\\d+)/).captures
  # ["Monday", "June", "4", "2007"]

This time i even previewed the post ;) One thing i see though is that markdown doesn't work like the docs say, 4 spaces indentation should result in a code-block.

By: Pistos

Pistos — Mon, 04 Jun 2007 13:20:07 +0000

manveru:

Your backslash got swallowed up by my Markdown plugin:

'this is a'.scan(/\w+/)[0,2]

But anyway: Thanks for pointing out this technique. However, I’m not sure it would let us grab arbitrary regexp groups, such as:

weekday, month, monthday, year =
"Monday, June 4, 2007"[
  /^(\w+), (\w+) (\d+), (\d+)/
]

By: manveru

manveru — Mon, 04 Jun 2007 09:35:56 +0000

first, second = 'this is a'.scan(/w+/)[0,2]

["this", "is"]