From: Hal Fulton <hal9000@...>
Date: 2003-09-04T00:12:46+09:00
Subject: Re: Possible to make compound if statements...

nobu.nokada@softhome.net wrote:

>>Also 'and' and 'or' have "extremely low precedence" (according to Ruby in a
>>Nutshell) so constructs using them _may_ behave differently than those
>>using && and || and my need parentheses to clear up ambiguities. I don't
>>have any good examples, but I'm sure someone does.
> 
> 
>   foo = false || bar = true	# foo = true, bar = true
>   foo = false or bar = true	# foo = false, bar = true
> 
> The former is equivalent to
> 
>   foo = (false or bar = true)
> 
> and the latter is
> 
>   (foo = false) || (bar = true)

In case a newbie gets confused: He does mean = here, not ==.
An assignment returns the value assigned.

> Also note that 'and' and 'or' have same precedence.
> 
> (foo or bar and bas) means ((foo || bar) && bas)
> but
> (foo || bar && bas) is (foo || (bar && bas))

This confuses me. So && is higher precedence than ||
but 'and' is not higher than 'or'.

In short:
    true or true and false    # false
    true || true && false     # true

For more reasons than readability, I think these
should certainly not be mixed:
    if a and b || c or d && e || f and g...

:)

Hal