The Ruby %r{ } expression
With %r
, you could use any delimiters.
You could use %r{}
or %r[]
or %r!!
etc.
The benefit of using other delimeters is that you don't need to escape the /
used in normal regex literal.
%r{}
is equivalent to the /.../
notation, but allows you to have '/' in your regexp without having to escape them:
%r{/home/user}
is equivalent to:
/\/home\/user/
This is only a syntax commodity, for legibility.
Edit:
Note that you can use almost any non-alphabetic character pair instead of '{}'. These variants work just as well:
%r!/home/user!
%r'/home/user'
%r(/home/user)
Edit 2:
Note that the %r{}x
variant ignores whitespace, making complex regexps more readable. Example from GitHub's Ruby style guide:
regexp = %r{
start # some text
\s # white space char
(group) # first group
(?:alt1|alt2) # some alternation
end
}x
this regexp matches all strings that ends with .gif, .jpg...
you could replace it with
/\.(gif|jpg|jpeg|png)$/i
\.
=> contains a dot(gif|jpg|jpeg|png)
=> then, either one of these extensions$
=> the end, nothing after iti
=> case insensitive
And it's the same as writing /\.(gif|jpg|jpeg|png)$/i
.