From: Robert Klemme <shortcutter@...>
Date: 2010-11-30T23:43:15+09:00
Subject: Re: class-wide begin/end blocks/exception handling

On Tue, Nov 30, 2010 at 3:39 PM, Robert Klemme
<shortcutter@googlemail.com> wrote:
> On Tue, Nov 30, 2010 at 1:06 AM, David E. <davidreynon@gmail.com> wrote:
>> So I have a class with a lot of methods, and each method has a begin/end
>> block
>>
>> class HiThere
>>  def one(stext)
>>  begin
>>   puts("Hi");
>>  rescue Exception => msg
>>   self.exceptionHandle(msg)
>>  end
>>  end
>>
>>  def two(stext)
>>  begin
>>   puts("Hi");
>>  rescue Exception => msg
>>   self.exceptionHandle(msg)
>>  end
>>  end
>>
>>  #etc etc
>>  #...
>> end
>>
>> ... Is there a way to put one begin/end block encompassing the whole
>> class/object? Sort of like an instance-wide begin/end block?
>
> Not directly, but you can do

Even better

class Proxy < BasicObject
  def initialize(obj, &handler)
    @obj = obj
    @handler = handler
  end

  def method_missing(*a,&b)
    @obj.send(*a,&b)
  rescue ::Exception => e
    @handler and @handler[e]
  end
end

def Proxy(obj, &handler)
  Proxy.new(obj, &handler)
end

irb(main):016:0> s = "foo"
=> "foo"
irb(main):017:0> s + "bar"
=> "foobar"
irb(main):018:0> s + 99
TypeError: can't convert Fixnum into String
        from (irb):18:in `+'
        from (irb):18
        from /opt/bin/irb19:12:in `<main>'
irb(main):019:0> pr = Proxy(s) {|e| p e.message}
=> "foo"
irb(main):020:0> pr + "bar"
=> "foobar"
irb(main):021:0> pr + 99
"can't convert Fixnum into String"
=> "can't convert Fixnum into String"
irb(main):022:0>

Cheers

robert



-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/