Question

我在lib文件夹中创建了Float类：

class Float
  def precision(p = 2)
    # Make sure the precision level is actually an integer and > 0
    raise ArgumentError, "#{p} is an invalid precision level. Valid ranges are integers > 0." unless p.class == Fixnum or p < 0
    # Special case for 0 precision so it returns a Fixnum and thus doesn't have a trailing .0
    return self.round if p == 0
    # Standard case
    (self * 10**p).round.to_f / 10**p
  end
end

在rspec测试中，有效。但是当应用程序运行时，会出现此错误：

undefined method `precision' for 5128.5:Float

如何使此覆盖工作？

Answer 1

Ruby已经为round实现了Float方法。您无需执行。

0.12345.round(2) # => 0.12
0.12345.round(3) # => 0.123

Answer 2

我认为应该这样做。

module MyFloatMod
  def precision(p = 2)
    # Make sure the precision level is actually an integer and > 0
    raise ArgumentError, "#{p} is an invalid precision level. Valid ranges are integers > 0." unless p.class == Fixnum or p < 0
    # Special case for 0 precision so it returns a Fixnum and thus doesn't have a trailing .0
    return self.round if p == 0
    # Standard case
    (self * 10**p).round.to_f / 10**p
  end
end

Float.send(:include, MyFloatMod)

编辑：几乎忘记了你还需要确保在应用启动时将其全部包含在内。

在Rails中覆盖Float类

2 个答案: