Use progn combination for `prompter:object-attributes`

[aartaka]

It's our frequent use-case to compose prompter:object-attributes (as in Nyxt hint-mode). Which tends to be ugly and not-exactly-composable after all—adding :around methods everywhere is quite a crude way to do things.

progn method combination seems to be a better shot—progn methods are not limited in number (if the specifies differ), while being perfectly composable. The downsides exist, though:

• There are no :before/:after methods—only primary, progn, and :around. This doesn't exactly matter, because these barely matter for prompter:object-attributes—it's a pure function not needing any watchers, after all.
• It requires more dispatching discipline, because dispatching over prompter:source might end up polluting lots of sources. But that's avoidable too—just use progn methods sparingly.

Mostly backwards-compatible too—I have no idea why anyone would use :before/:after methods in their prompts, so that shouldn't break anything.

EDIT: formatting, typos, and details

[aartaka]

Hmmmmmm, it seems to break because progn combination has no primary methods 0_o That I didn't know. Maybe write our own combination then?

[Ambrevar]

That's an option, I suppose. Then we can support :before and :after.

But can you give an example how progn would be better here?

[aartaka]

That's an option, I suppose. Then we can support :before and :after.

But we don't really need them ( ͡° ͜ʖ ͡°) Maybe to concat to the beginning/end of the thing, but that's achievable with :around...

I guess our own combination with prefixing and suffixing the list and with primary method would work better after all.

But can you give an example how progn would be better here?

It'd be better in appending attributes from several inherited sources/objects. The main application, as I've said, is Nyxt's hint-mode.

Oh, wait, it should be append instead of progn （＠´＿｀＠）

[Ambrevar]

I see it's useful for hint-mode, but is it so common that we want to reuse all the attributes of a parent? Seems a bit specific to me. The problem with an append method is that we don't control the attribute order much.

[Ambrevar]

Note: maybe the loop in the hint-mode example is needlessly complicated. Does it do the same as this?

(let ((attributes '(("URL" "http://foo.org"))))
  (mapcar (lambda (attr)
            (or (assoc attr attributes :test 'string=)
                (list attr "")))
          '("URL" "Body")))

[aartaka]

Note: maybe the loop in the hint-mode example is needlessly complicated. Does it do the same as this?

(let ((attributes '(("URL" "http://foo.org"))))
  (mapcar (lambda (attr)
            (or (assoc attr attributes :test 'string=)
                (list attr "")))
          '("URL" "Body")))

No, it's merely ensuring the attribute is there. But I'm guessing we can simplify it too if we have a reasonable method combination.