livecheck: add support for casks

[SeekingMeaning]

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---

This allows brew livecheck to work on casks and adds a new livecheck stanza to the Cask DSL. Since many casks use methods such as version.before_comma, a new version field is added to the Livecheck class that accepts either a String or a valid Symbol (before_comma, after_comma, before_colon, after_colon)

Example livecheck for ansible-dk:

livecheck do
  url :homepage
  version :before_comma
end

[miccal]

Great work.

Would the url in the livecheck block accept :appcast?

[MikeMcQuaid]

Very nice! I'd love @samford and @nandahkrishna to take a look before this is merged.

[core-code]

Would the url in the livecheck block accept :appcast?

also implicitly using the :appcast if nothing is specified would make sense.

[nandahkrishna]

Thanks @SeekingMeaning for this PR! Just a few minor comments. Also, would --formulae-only and --casks-only flags for the brew livecheck developer command be useful?

[samford]

I don't often find myself in homebrew-cask but I happened to be looking at a cask the other day and thinking about adding support to livecheck. Good timing!

I'm in the process of reviewing and testing this and I'll have some feedback and requested changes once I'm finished.

[SeekingMeaning]

Would the url in the livecheck block accept :appcast?

@miccal Yes

also implicitly using the :appcast if nothing is specified would make sense.

we might want to have the appcast URL take highest priority (and be the first addition to the urls array).

@core-code @nandahkrishna Done (I'm assuming all casks at least have url since a cask would be useless without it)

Also, would --formulae-only and --casks-only flags for the brew livecheck developer command be useful?

Yes, probably

"version"  => @version,

Would we want to omit this from the hash unless @formula_or_cask is a cask?

Maybe, but the doc comment says "Returns a Hash of all instance variable values"

-      @livecheck ||= Livecheck.new(self)
-      return @livecheck unless block_given?
-      raise CaskInvalidError.new(cask, "'livecheck' stanza may only appear once.") if @livecheckable
-      @livecheckable = true
-      @livecheck.instance_eval(&block)
+      set_unique_stanza(:livecheck, !block_given?) do
+        livecheck = LiveCheck.new(self)
+        livecheck.instance_eval(&block)
+        livecheck
+      end

@reitermarkus I actually did this initially but the Livecheck utility requires livecheck method to return a non-nil value

[samford]

Thanks for your work here, @SeekingMeaning.

There may be more room for improvement outside of my specific comments below but this is my first pass through this. Since this is a significant addition, I would prefer that we take our time with this to make sure it's in good shape before merging.

One thing that sticks out to me right now is the relative verbosity of the various formula_or_cask language. It would be nice if we could find a generic way to refer to the concept of a formula or cask that's shorter but maybe this is just me.

---

There may be value in having a flag that allows us to restrict livecheck to only work with either formula or casks. Maybe something like --type=formula/--type=cask or individual flags like --formula-only/--cask-only. This would allow users to only work with one or the other for a given run, which may be useful in conjunction with the --all or --tap= options. This should be relatively easy to handle, since it only affects the Livecheck#livecheck method.

Edit: I just now saw Nanda's suggestion about the same flags, ahah. I'm not surprised we had the same idea.

---

From what I'm seeing, roughly 1/3 of the ~3645 casks have a URL that matches a strategy (~87% use the Git strategy) and a fair number of those produce an okay result. Hopefully we can look through the URLs and identify patterns that can be handled with additional strategies. If not, we're looking at 2500+ additional items to write livecheck blocks for, on top of the ~600 formulae that still need livecheck blocks.

[SeekingMeaning]

One thing that sticks out to me right now is the relative verbosity of the various formula_or_cask language. It would be nice if we could find a generic way to refer to the concept of a formula or cask that's shorter but maybe this is just me.

Yes, I agree — what about recipe or item?

Hopefully we can look through the URLs and identify patterns that can be handled with additional strategies.

I'll try my best

[nandahkrishna]

I just now saw Nanda's suggestion about the same flags, ahah.

😄

As for the flags, it seems brew list has --formula/--formulae and --cask/--casks so we could go with those for consistency.

[SeekingMeaning]

List of casks without an automatic livecheck strategy (2,319 total): https://gist.github.com/SeekingMeaning/6c7a6d072a562c6ac474d5c0bb558076

[MikeMcQuaid]

One thing that sticks out to me right now is the relative verbosity of the various formula_or_cask language. It would be nice if we could find a generic way to refer to the concept of a formula or cask that's shorter but maybe this is just me.

I'm fine with this, personally. Would definitely prefer over anything like fc being used more widely.

[core-code]

List of casks without an automatic livecheck strategy (2,319 total): https://gist.github.com/SeekingMeaning/6c7a6d072a562c6ac474d5c0bb558076

if you are looking for text patterns to find new versions of casks - i can contribute a few dozen of those.
patterns.txt

[reitermarkus]

@SeekingMeaning, anything still missing here?

[MikeMcQuaid]

@SeekingMeaning Would love to get this in in the nearish future. We can iterate on this in future PRs; I don't think this needs to be perfect to be merged.

[BrewTestBot]

Review period ended.

[samford]

With this having been rebased, I'll take another pass to review and test this as soon as I can. Thanks for helping to get this into shape, @reitermarkus.

[reitermarkus]

I have removed version completely for now, since I don't think it is really that useful for casks to know whether the version actually increased.

[samford]

Thanks, everyone!