Legit closify remove global vcs #1538
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Yes, Emacs makes extensive use of dynamic bindings/scope: that's not a
reason we should do the same. Common Lisp supports lexical scoping,
unlike Elisp when it started out, and in my opinion we should really,
*really*, try to avoid dynamic binds where a function parameter would
do.
Yes, this adds the need to plumb an extra parameter around. That's well
worth the cost: we can always package/split function parameters as
needed and as they make sense, whereas dynamic bindings may prove to be
a *huge* pain point in the future if Lem starts making use of paralellism.
The Emacs documentation itself puts it succinctly [1]
> Lexical binding opens up many more opportunities for optimization,
> so programs using it are likely to run faster in future Emacs versions.
> Lexical binding is also more compatible with concurrency,
Now, focusing on Legit itself: much of the in lem/porcelain uses the
pattern
```
(defun some-legit-function (vcs)
(case vcs
(:git (git-fn))
(:hg (hg-fn))
(:t (fallthrough))))
```
There's no reason to have all of this dispatch logic done manually: this
is a textbook case for using generic functions. Now, the thing is that
generic functions need something to dispatch *on*. And it's pretty clear
that the VCS parameter (representing, really, the repository [2]) is the
perfect thing for that.
By switching all the `legit-function`s to be generic functions, the
implementation for each VCS can also define their `vcs` objects to
contain whatever data they might find useful: whether that's some sort
of legit-side cache for commits, FFI handles (will be useful for libgit2
support for instance), etc.
[1] https://www.gnu.org/software/emacs/manual/html_node/elisp/Lexical-Binding.html
[2] Might be worth a rename, but I don't want to clutter this particular
change.
It doesn't do anything: the one place it's actually called, we know that we're in a git project already. The equivalent hg and fossil callsites actually call the bespoke functions directly
The variable is unused, according to grep
The system is loaded by default now.
More flexible
Also, update some of the :documentation for the porcelain functions
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the failed CI is |
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Legit's code base is now a little OO and the VCS logic is split into their own files.
The goal that is now achieved without bugs is that we can have more than 1 interactive rebase in process, without re-inventing an OO with too many global variables and manual dispatch.
I tested the best I can, specialy the interactive rebase, for git and other VCSs (which must show a message, not fail).
replaces #1451