On Mon, Jul 5, 2021, 12:56 PM Barry Scott <ba...@barrys-emacs.org> wrote:
>
>
> On 5 Jul 2021, at 08:07, Thomas Güttler <i...@thomas-guettler.de> wrote:
>
> This means backticks, but without the dollar sign.
>
>
> In bash the backtick was so often a problem that $(cmd) was added.
>
> Having removes the grit-on-Tim's-screen backtick in python 3 I would
> not like to see it return with its issue of being confused with
> single-quote.
>
One mitigation is that the backtick should always require a tag as a
prefix. So seeing something like
elem = html`<p>Some item: {value}</p>`
is hopefully fairly obvious what's going on - it's not just going to be
mixed up with a single quote. Uses like log(f`foo`) should be hopefully
discouraged, in the same way that we don't use l (that's the lower-case
letter L if you're not reading this email with the numeric codepoints) as a
variable, but we are happy enough to write something like limit = 42 - it's
clear in the context.
However, I think the Bash example is exactly illustrative of the opposite.
So in reviewing at least this one FAQ on the topic
http://mywiki.wooledge.org/BashFAQ/082, it reminds me of why I don't use
backticks in Bash - it's the lack of nesting support when compared to
$(...).
Ironically, this nesting is exactly what backticks can help here on - an
unused character as of Python 3, commonly used for building some type of
string/identifier in a variety of languages, that we can give some nice
semantics that allows for simple nesting when used in conjunction with
braces delimiting expressions. Such braces of course always give us a new
nesting, similar to the statement in the wiki above that "$() forces an
entirely new context for quoting, so that everything within the command
substitution is protected and can be treated as though it were on its own,
with no special concern over quoting and escaping." That this usage of
backticks has worked quite well for JavaScript provides some useful
confirmation.
I also expect that no one will confuse this with Bash usage, given that's
going to be in Python code - except perhaps in a readily written sh
function (so something like sh`...`, which returns a list of stdout or
something like that and makes use of shlex, etc). I will leave what horrors
that could actually look like to the reader :) although in limited form, it
could be quite useful.
- Jim
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