I'm following a tutorial on regular expressions in ruby, but a method called regex that seems not working
Tutorial
re = /(\w*)\s(\w*),\s?([\w\s]*)/
match1 = str1.match re
match2 = str2.match re
match1.regex # => wsw,s[ws] (this is IRB's unique way of showing regular expressions; it will still work normally)
My console
The regex method the method throws an error
1.9.3-p547 :033 > re = /(\w*)\s(\w*),\s?([\w\s]*)/
=> /(\w*)\s(\w*),\s?([\w\s]*)/
1.9.3-p547 :034 > match1 = str1.match re
=> #<MatchData "Joe Schmo, Plumber" 1:"Joe" 2:"Schmo" 3:"Plumber">
1.9.3-p547 :035 > match2 = str2.match re
=> #<MatchData "Stephen Harper, Prime Minister" 1:"Stephen" 2:"Harper" 3:"Prime Minister">
1.9.3-p547 :036 > match1.regex
NoMethodError: undefined method `regex' for #<MatchData "Joe Schmo, Plumber" 1:"Joe" 2:"Schmo" 3:"Plumber">
from (irb):36
from /home/fernando/.rvm/rubies/ruby-1.9.3-p547/bin/irb:12:in `<main>'
1.9.3-p547 :037 >
I think it should be
match1.regexp
with a final 'p'
Related
In Rails 3.0, the helper method simple_format changes the parameter itself.
I expected that it only returns the wrapped text.
2.0.0-p648 :001 > Rails.version
=> "3.0.20"
2.0.0-p648 :002 > s = "Hello"
=> "Hello"
2.0.0-p648 :003 > helper.simple_format(s)
=> "<p>Hello</p>"
2.0.0-p648 :004 > s
=> "<p>Hello</p>"
I checked with Rails 4.2 and it doesn't change the text.
Can someone please explain it?
Sam
The difference between implementations of this method in Rails 4.2 and Rails 3.0 is that in Rails 3.0 the passed string is modified (mutated by gsub!) and in Rails 4.2 it's not (it just returns a new modified string):
Rails 4.2:
2.4.0 :006 > s = "hello"
=> "hello"
2.4.0 :007 > simple_format s
=> "<p>hello</p>"
2.4.0 :008 > s
=> "hello"
The source code of different implementations can be found in the documentation
What is the difference between Ruby’s Hash and ActiveSupport’s HashWithIndifferentAccess? Which is the best for dynamic hashes?
Below is the simple example that will show you difference between simple ruby hash & a "ActiveSupport::HashWithIndifferentAccess"
HashWithIndifferentAccess allows us to access hash key as a symbol or string
Simple Ruby Hash
$ irb
2.2.1 :001 > hash = {a: 1, b:2}
=> {:a=>1, :b=>2}
2.2.1 :002 > hash[:a]
=> 1
2.2.1 :003 > hash["a"]
=> nil
ActiveSupport::HashWithIndifferentAccess
2.2.1 :006 > hash = ActiveSupport::HashWithIndifferentAccess.new(a: 1, b:2)
NameError: uninitialized constant ActiveSupport
from (irb):6
from /home/synerzip/.rvm/rubies/ruby-2.2.1/bin/irb:11:in `<main>'
2.2.1 :007 > require 'active_support/core_ext/hash/indifferent_access'
=> true
2.2.1 :008 > hash = ActiveSupport::HashWithIndifferentAccess.new(a: 1, b:2)
=> {"a"=>1, "b"=>2}
2.2.1 :009 > hash[:a]
=> 1
2.2.1 :010 > hash["a"]
=> 1
class HashWithIndifferentAccess is inherited from ruby "Hash" & above special behavior is added in it.
In Ruby Hash:
hash[:key]
hash["key"]
are different. In HashWithIndifferentAccess as the name suggests, you can access key either way.
Quoting official documentation to this:
Implements a hash where keys :foo and "foo" are considered to be the
same.
and
Internally symbols are mapped to strings when used as keys in the
entire writing interface (calling []=, merge, etc). This mapping
belongs to the public interface. For example, given:
hash = ActiveSupport::HashWithIndifferentAccess.new(a: 1)
You are
guaranteed that the key is returned as a string:
hash.keys # => ["a"]
#!/usr/bin/ruby
puts "Please enter the path-name of the directory:"
p = STDIN.gets
isdir = File.directory?(p)
puts "#{isdir} #{p}"
it always return me a false! even though I know the user input is a directory. I think (p) is not working as a parameter. So i think its saying that p is not a directory not the user input for example "/usr/bin/". any help?
Using p = STDIN.gets '\n' was getting appended. Instead you can use gets.chomp. Also you need to use File.expand_path. Check the example below.
# My irb
1.9.3-p545 :002 > p = gets.chomp
~/.ssh
=> "~/.ssh"
1.9.3-p545 :003 > File.directory?(p)
=> false
1.9.3-p545 :004 > File.exists? File.expand_path(p)
=> true
The p value is not strictly equal to what you expect it to be. It contains \n at the end:
# in my irb:
1.9.3p392 :010 > p = STDIN.gets
/home/
=> "/home/\n"
1.9.3p392 :011 > isdir = File.directory?(p)
=> false
1.9.3p392 :012 > isdir = File.directory?(p.strip)
=> true
The strip method:
Strips entire range of Unicode whitespace from the right and left of the string.
Source: http://apidock.com/rails/ActiveSupport/Multibyte/Chars/strip
I am using Rails 4.0.0 with Ruby 2.0.0 p247. I am writing an URL regexp matcher but I have no idea why it does not work:
2.0.0-p247 :033 > REGEXP = %r{\Ahttps:\/\/#{ Rails.configuration.aws[:bucket] }\.s3(-#{Rails.configuration.aws[:region]}|)\.amazonaws\.com\/(?<path>uploads\/.+\/(?<filename>.+))\?.+\z}.freeze
=> /\Ahttps:\/\/test-gem\.s3(-eu-west-1|)\.amazonaws\.com\/(?<path>uploads\/.+\/(?<filename>.+))\?.+\z/
2.0.0-p247 :034 > url = "https://test-gem.s3.amazonaws.com/uploads/2alrg16mvx6r-29590d114fb3257846c1a03330418da9/3031674-poster-p-1-for-25.jpg"
=> "https://test-gem.s3.amazonaws.com/uploads/2alrg16mvx6r-29590d114fb3257846c1a03330418da9/3031674-poster-p-1-for-25.jpg"
2.0.0-p247 :035 > REGEXP.match(url)
=> nil
But when I try to debug in things like Rubular, it does work. Any idea? Thanks!
Remove \?.+ in the end if your regexp
Might be a bug with Ruby 2.0.0. I'm using 2.1.3 and it works like you'd expect.
> r = /\Ahttps:\/\/test-gem\.s3(\A-eu-west-1\z|)\.amazonaws\.com\/(?<path>uploads\/.+\/(?<filename>.+))\z/
=> /\Ahttps:\/\/test-gem\.s3(\A-eu-west-1\z|)\.amazonaws\.com\/(?<path>uploads\/.+\/(?<filename>.+))\z/
> r.match("https://test-gem.s3.amazonaws.com/uploads/2alrg16mvx6r-29590d114fb3257846c1a03330418da9/3031674-poster-p-1-for-25.jpg")
=> #<MatchData
"https://test-gem.s3.amazonaws.com/uploads/2alrg16mvx6r-29590d114fb3257846c1a03330418da9/3031674-poster-p-1-for-25.jpg"
path:"uploads/2alrg16mvx6r-29590d114fb3257846c1a03330418da9/3031674-poster-p-1-for-25.jpg"
filename:"3031674-poster-p-1-for-25.jpg">
I have the following expression that I have tested in Rubular and that successfully matches against a snippet of HTML:
Official Website<\/h3>\s*<p><a href="([^"]*)"
However, when I run the expression in Ruby, using the following code, it returns no matches. I've reduced it down to "Official\s*Website" and it matches that, but nothing further.
Are there any additional options I need to set, or anything else that I need to do to configure Ruby/Rails to start tracking Rubular?
matches = sidebar.match(/Official\s*Website<\/h3>\s*<p><a href="([^"]*)"/)
if matches.nil?
puts "no matches"
else
puts "matches"
end
This is the relevant part of the snippet I'm matching against:
<h3>Official Website</h3><p>website.com</p>
your regular expression is correct. rubular should be working the same way your code does.
i tested it against ruby 1.8.7 and 1.9.3
irb(main):006:0> sidebar = ' <h3>Official Website</h3><p>website.com</p>'
=> " <h3>Official Website</h3><p>website.com</p>"
irb(main):007:0> sidebar.match(/Official\s*Website<\/h3>\s*<p><a href="([^"]*)"/)
=> #<MatchData "Official Website</h3><p><a href=\"http://website.com\"" 1:"http://website.com">
-
1.9.3p0 :005 > sidebar = ' <h3>Official Website</h3><p>website.com</p>'
=> " <h3>Official Website</h3><p>website.com</p>"
1.9.3p0 :006 > sidebar.match(/Official\s*Website<\/h3>\s*<p><a href="([^"]*)"/)
=> #<MatchData "Official Website</h3><p><a href=\"http://website.com\"" 1:"http://website.com">
if you want to quickly check why stuff is not working, you should try it in IRB or in your rails console. most of the times it's typo or bad encoding.