Converting strings to booleans, symbols, etc

ruby-talk
1

Hi,

I am parsing an xml document, and I wanted to know if there is a quick
built in way to convert a string to a symbol or a boolean. an example
xml doc would be:

<test id="first" search="false">data</test>

Now I know I can do some string compares, and set the variable
accordingly, but I was wondering if there are shortcuts, much like the
to_i method.

thanks!

···

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2

The symbol is easy, anyway:
http://www.ruby-doc.org/core/classes/String.html#M000825

Once you're there, making a compare for true/false isn't so much code.
But maybe someone else has a cleaner solution to that.

Ben

···

On Feb 8, 2008 12:51 PM, an an <dtown22@gmail.com> wrote:

I am parsing an xml document, and I wanted to know if there is a quick
built in way to convert a string to a symbol or a boolean.

3

Here some sample code to get your brain churning ...

class String
   # The inverse of 'to_s'
   def s_ot
     begin
       return Integer(self)
     rescue ArgumentError
       (return Float(self)) rescue nil
     end

     case self
     when %r/^true|yes$/i; true
     when %r/^false|no$/i; false
     when %r/^nil|none$/i; nil
     when %r/^:\w+$/; self.tr(':','').to_sym
     else self end
   end
end

"1.0".s_ot #=> 1.0 (as a Float)
"2".s_ot #=> 2 (as a Fixnum)
"no".s_ot #=> false
"none".s_ot #=> nil
":string".s_ot #=> :string (as a Symbol)

Happy Friday everyone!

Blessings,
TwP

···

On Feb 8, 2008, at 11:51 AM, an an wrote:

Hi,

I am parsing an xml document, and I wanted to know if there is a quick
built in way to convert a string to a symbol or a boolean. an example
xml doc would be:

<test id="first" search="false">data</test>

Now I know I can do some string compares, and set the variable
accordingly, but I was wondering if there are shortcuts, much like the
to_i method.

4

You can create yourself some. One example:

CONV = {
   "false" => false,
   "true" => true,
   "0" => 0,
   "1" => 1,
   # more common / important values
}

def convert(s)
   x = CONV[s]

   if x.nil?
     x = case x
       when /\A[+-]?\d+\z/
         s.to_i
       when /\A[+-]?\d+(?:\.\d+)?\z/
         s.to_f
       # more
       else
         x
     end
   end

   x
end

Kind regards

  robert

···

On 08.02.2008 19:51, an an wrote:

Hi,

I am parsing an xml document, and I wanted to know if there is a quick
built in way to convert a string to a symbol or a boolean. an example
xml doc would be:

<test id="first" search="false">data</test>

Now I know I can do some string compares, and set the variable
accordingly, but I was wondering if there are shortcuts, much like the
to_i method.

5

Day wrote:

···

On Feb 8, 2008 12:51 PM, an an <dtown22@gmail.com> wrote:

I am parsing an xml document, and I wanted to know if there is a quick
built in way to convert a string to a symbol or a boolean.

The symbol is easy, anyway:
class String - RDoc Documentation

Once you're there, making a compare for true/false isn't so much code.
But maybe someone else has a cleaner solution to that.

Ben

thanks...thats the type of stuff i was looking for...im used to java,
and I am actively tried to avoid coding Java style in ruby, but
sometimes its hard to figure out the shortcuts that ruby provides
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