From: Kristof Bastiaensen <kristof@...>
Date: 2004-06-02T09:03:38+09:00
Subject: Re: What is the equivalent of Python's "%s" % "MyString"?

Hi,

On Tue, 01 Jun 2004 18:38:32 +0000, Sam Sungshik Kong wrote:

> Hello!
> 
> I am studying Ruby and have been using Python.

Good!

> I apologize for my negligence not to check out the whole document first.
> What is the equivalent of the following Python's expressions?
> 
> s = "My name is %s and my age is %d." % ("Sam", 34)
> 

This is almost identical in ruby:
"My name is %s and my age is %d." % ["Sam", 34]

> or
> 
> s = "My name is %(name)s and my age is %(age)d." % {"name": "Sam", "age":
> 34}
> 
> or
> 
> format = "My name is %(name)s and my age is %(age)d."
> di = {"name": "Sam", "age": 34}
> s = format % di
> 
> 
> I know that ruby has "#{name}" expression.
> But that requires a variable named "name" in advance.
> I want to bind the format string and data later.
> What is the closest thing in ruby?
> I find the python expression quite useful.

I don't think Ruby supports this from itself.
Personally I find that #{} is enough in most cases.
If you really need this, you could define it with
the following code:

class String
  alias :old_percent :%
  def %(format)
    return old_percent(format) if
      not format.is_a? Hash

    arr = []
    str = self
    while (match = /%\((.*?)\)/.match(str))
      str = match.post_match
      arr << format[match[1]]
    end
    self.gsub(/%\(.*?\)/, "%").old_percent(arr)
  end
end

"My name is %(name)s and my age is %(age)d." % {"name" => "Sam", "age" =>
34}

Regards,
Kristof