From: Austin Ziegler <halostatue@...>
Date: 2005-11-17T06:50:24+09:00
Subject: Re: Object#to_b

On 11/16/05, Daniel Schierbeck <daniel.schierbeck@gmail.com> wrote:
> Currently, as far as I know, `if' and `unless' merely check if an object
> is of either types NilClass or FalseClass. This seems to contradict the
> duck-typing paradigm. I propose that we implement a method Object#to_b
> that is called by `if' and `unless'. It should return a boolean value.
> That way, a developer can decide whether or not an object should
> evaluate to true or false.

> One problem I see with this proposal is that it seems like a lot of
> people check if a variable has been set by writing `if var ...'. This
> change would require that people wrote `unless var.nil?', which I
> personally find more correct as well.

This would break a lot of my code, personally. I used to use "unless
var.nil?" but it is easier to say:

  if var and var.foo

than:

  if (not var.nil?) and var.foo

I'm not *quite* sure what the "unless" version of the test would be:

  unless var.nil? or var.foo.nil?

Not quite what I want. I think that #to_b would be problematic,
especially in the example that you gave, since it's more expressive to
say:

  if conn.open?

than:

  if conn

which implies you're checking to see if conn is really there.

-austin
--
Austin Ziegler * halostatue@gmail.com
               * Alternate: austin@halostatue.ca