Guido wrote
> Perhaps someone can do some research and unearth real code that contains
> series of += assignments that would become more readable by collapsing them
> into a single line using the proposed construct.
Here's some notes towards finding (or constructing) such examples.
First note that it's awkward to unpack
a, b = b, a # swap values
because this simple solution does not work (as we need a temporary)
a = b
b = a
so perhaps our example should require unpacking, to avoid the use of temporarys.
Now consider, for example,
wibble(4).wobble.cheese += 8
This has semantics
tmp1 = wibble(4).wobble
tmp2 = tmp1.cheese
tmp1.cheese = tmp2 + 8
which is different to and harder to write than
wibble(4).wobble.cheese = wibble(4).wobble.cheese + 8
so perhaps our example should involve an assignable expression, such
as wibble(4).wobble.cheese.
So here's a concocted example.
ns.aaa.a, ns.bbb.b, += 2 * ns.bbb.b, 3 * ns.aaa.a
I describe this as a namespace-of-values, whose values change at least
logically all at the same time. In other words, it's something like
vector = apply(matrix, vector)
This example can be expanded by first computing the values, and then
doing the assignment.
tmp1, tmp2 = ns.bbb.b, ns.aaa.a
ns.aaa.a += 2 * tmp2
ns.bbb.b += 3 * tmp1
The following avoids the double lookup of ns.aaa.a (and of ns.bbb.b).
tmp1, tmp2 = ns.bbb.b, ns.aaa.a
ns.aaa.a = tmp1 + 2 * tmp2
ns.bbb.b = tmp2 + 3 * tmp1
So far, this is the best artificial example I've come up with.
--
Jonathan
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