> On 10 Jun 2016, at 20:45, Xiaodi Wu <[email protected]> wrote:
>
> I'm sorry, but until this discussion I had never heard of a coding style that
> advocates for conservation of vertical space. There's a lot of argument
> whether 80 characters is still a relevant line length, but I've never heard
> discussion that a single long line is better than multiple lines as a general
> principle.
We’re not talking about a single super long line here, my actual uses of for in
where don’t get much longer than the examples I’ve given, besides which the
where keyword itself does a good job of breaking up the line into distinct
pieces. Compared to say a long line full of chained .filter and .map or
whatever it’s very clean.
At no point am I advocating shoving everything onto one line just for the sake
of it, however, without a where clause a for in loop’s opening line tends to be
very short so it leaves a nice chunk of extra space that’s ideal for a simple
condition. Anything longer can, and absolutely should, span multiple lines in
whatever form the developer prefers, no-one is suggesting that where clauses
should remain in so we can ruin our code by shoving as much as possible on one
line.
Regarding some of the numbers that have come up about for in vs for in where
loops (in my own code I’m close to maybe of 20% of my for in loops using it),
it’s important to recognise that the use of the where clause isn’t well
advertised. When I started out with Swift I only knew that it could be used on
cases in a switch statement, and later that it was used with complicated
generics. It wasn’t until I joined the mailing list that I found out it could
be used with conditional bindings and loops, but when I did I started using it
almost immediately.
Plus a lot of developers are coming from other languages where nothing like
this existed, so if they don’t discover it somewhere it’s not surprising if
they don’t use it. Also, the important figures aren’t actually for in versus
for in where, what’s needed is a count of for in where versus loops that use
either if/guard continue (not break) or .filter() (i.e- only loops that could
use a where clause but don’t). Most for in loops visit every element so it’s
not surprising that they outnumber for in where by a large margin. I use it
quite a bit in place of .filter(), and I’d use this form even more if there
were a breaking alternative, I probably wouldn’t use a combined filtering and
breaking version much though, but I wouldn’t be opposed to the possibility.
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