From: Alan Johnson <alan.wayne.johnson@...>
Date: 2008-11-26T09:10:51+09:00
Subject: Re: Begin else pattern question

On Tue, Nov 25, 2008 at 3:19 PM, Mikel Lindsaar <raasdnil@gmail.com> wrote:
> What is the cleanest way of doing:
> def initialize(value)
>  begin
>    if value == 'blah'
>      a_action
>    else
>      b_action
>    end
>  rescue
>    b_action
>  end
> end
>
> That is.  If a is needed and doing a throws an exception, do b instead.
>  Otherwise, if a is not needed do b.
>
> Or is that the cleanest way?
>
> By cleanest, I mean l don't like calling b_action twice in the method if I
> don't have to, but it's a trade off on readability... and I don't _like_ the
> way the code looks now :)
>
> Any other simpler way to do this pattern?
>
> Mikel
>

A device that turns exceptions into a return value might assist.
Perhaps something like this:

def succeeded
    begin
        yield
        true
    rescue
        false
    end
end

def a_action(succeed)
    raise "failed" if !succeed
    print "a_action\n"
end

def b_action
    print "b_action\n"
end

def action(value, succeed)
    b_action if !(value == "blah" && succeeded { a_action(succeed) })
end


action "blah", true
action "blah", false
action "not blah", true
action "not blah", false

-- 
Alan