PEP-308 a "simplicity-first" alternative

[Erik Max Francis]

Bengt Richter wrote:

> Why do you quote the bad old hack and leave out the better alternative
> I was proposing, and which was the point?

Because I have addressed that alternative.  Not only do I not believe
that it is not better, I believe that it is worse.  It is _more_
idiomatic and _less_ readable.

> Are you saying that
> 
>     x and {y} or {z}
> 
> is not readable, assuming you're familiar with the old idiom?
> Newbie-obvious no, but how long would it take you to learn to use it?

People already have the (actually correct) idioms like

	(C and [x] or [y])[0]
	(C and lambda: x or lambda: y)()

As far as I know, nobody considers those good solutions; they are
totally incomprehensible unless you already understand the whole sordid
issue with the and/or syntax and why it doesn't work.  The purpose of a
conditional operator is for it to be readable.  These two solutions are
not readable.

Your solution is going from a broken and unreadable idiom and attempting
to make it unbroken.  That is totally the wrong approach of good
language design; you may make it unbroken, but it's damn sure still
unreadable.

You're talking about "assume you're familiar with the old idiom" as if
that were a positive trait.  Nobody _likes_ the old idiom -- that's the
whole point here.  It's unreadable and lends no hint as to what is meant
by it.

> Especially since you could just use it, and ignore fine points
> about what would happen if a bare y was logically a false value.

So can you rigorously define the behavior of an expression with {}
markers in the general case?  Can you even rigorously define it here? 
What happens when it appears somewhere other than one of the operands to
a logical operator, what then?  Can you even fully define its semantics?

You're patching up a broken, ugly idiom with a complicated,
hard-to-explain syntax that will only make the broken idiom more
idiomatic.  It makes it no longer broken, but it makes it less readable.

> Is this really cleaner?
> 
>    (if x: y else: z)

Yes, I think it is.  It's clear and easily understandable even to
someone who's never seen it before.  It's light-years ahead of any
solution I've seen based on patching up the unreadable and/or hack.

-- 
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