From: ole __ <oliver.saunders@...>
Date: 2007-06-21T07:17:53+09:00
Subject: Code Critique: check if int or float

Hello again folks,

I'm really starting to like this language. I'm working towards building
a simple expression evaluator. I couldn't seem to find any methods for
testing whether a string contains an integer or float. In PHP (where I'm
from) you've got your is_numeric(). Is there such a method in Ruby?

Anyway, under the assumption that there wasn't and to learn a bit I
decided to add the methods i? and f? to String. I was wondering if I
could get a bit of a critique on this code because I'm still ultra new
to Ruby.

I'm a TDD maniac, so I've got miself a test case in there too:
===============================
class String
  # Strict test whether the string is a valid integer
  # Underscores are not permitted.
  # allowScientific is false by default because "4e3".to_i is 4
  def i?(allowScientific = false)
    if allowScientific
      return (self =~ /^-?\d+(e-?\d+)?$/) != nil
    end
    (self =~ /^-?\d+$/) != nil
  end
  # Strict test whether the string is a valid float.
  # i.e. 4 is not but 4.0 is. Scientific notation acceptable.
  def f?(allowScientific = true)
    if allowScientific
      return (self =~ /^-?\d*\.\d+(e-?\d+)?$/) != nil
    end
    (self =~ /^-?\d*.\d+$/) != nil
  end
end

require 'test/unit'

class StringExtensionsTest < Test::Unit::TestCase
  def testI
    assert '45'.i?
    assert '-3'.i?
    assert !'3s'.i?
    assert !'3_000'.i?
    assert !'3e3'.i?
  end
  def testIScientific
    assert !'e4'.i?(true)
    assert '4e2'.i?(true)
    assert '-8e3'.i?(true)
    assert '-5e-25'.i?(true)
  end
  def testFBasic
    assert !'3'.f?(false)
    assert '3.0'.f?(false)
    assert '-25.36'.f?(false)
    assert '.52'.f?(false)
    assert '-.14'.f?(false)
  end
  def testFScientific
    assert !'e1'.f?
    assert !'4e1'.f?
    assert '3.12e1'.f?
    assert '-2.0e-3'.f?
    assert '-.6e2'.f?
  end
end
===============================
4 tests, 19 assertions, 0 failures, 0 errors
===============================

Final question, what are your feelings on camelCase and Ruby's apparent
shunning of it?

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