Alexey Verkhovsky wrote:
On 5/31/07, Eric Armstrong <[EMAIL PROTECTED]> wrote:
Ruby Code:
- always use && and ||, not 'and' and 'or'
Why is that? For consistency with Java? Or is there
some other benefit?
This is a convention in Rails core. Its origin is that 'and' and 'or'
have priority lower than && and ||, and lower than assignment. Which
sometimes leads to unexpected behavior.
E.g.
x = y && z
is not the same as
x = y and z
Good golly. Lower than "="? Horrors. That's the kind of
thing that gives me fits--synonymous terms that have
semantically different behavior. It's just a bad choice.
I'm really glad I asked. It's the kind of thing you could
stare at for an hour, wondering what's wrong.
I would append the statement to read:
"Always use && and || in conditionals, rather than 'and'
and 'or'. (Since the latter have lower precedence even
than assignment, they can lead to unexpected behaviors.)"
Add the exception for control flow, if you must. But I try
not recall such trivialities as precedence. That's important
for a language designer to know, but its something a
language user shouldn't have to understand to use the
language effectively. (So yes, I parenthesize the hell out
of my expressions.)
:_)
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