Switch to dependency injection for the main CLI #6331
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Sets up some foundations for the coming coverage sprint: - a standard way to inject dependencies into this CLI app (via app.Metadata) - a standard way to read and write CLI text (not yet used, but hopefully the intent is clear enough) - many more error returns to cover the new branches Next steps are roughly: - write tests! - remove all `fmt.*Print*` calls and use the appropriate output writer instead. - this will expose more error branches: we should be using them, as output can fail if a pipe fails. - remove all stdin-reading calls, and use the input reader instead - this will allow us to answer prompts / continue paging in tests
Groxx
requested review from
Shaddoll,
neil-xie,
davidporter-id-au,
shijiesheng,
jakobht,
3vilhamster,
sankari165,
dkrotx,
taylanisikdemir and
demirkayaender
as code owners
taylanisikdemir
approved these changes
Oct 7, 2024
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| // currently Metadata is completely unused by urfave/cli/v2, and it has fewer ways to fail | ||
| // than using the ctx.Context (as you must use RunContext to supply dependencies via the Context). | ||
| // | ||
| // this is fairly easy to move to ctx.Context if needed, it just leads to slightly more complex code. | ||
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| // intentionally panics when an invalid context is not passed in, to help collapse logic branches. | ||
| // generally speaking this should not be possible to trigger without doing something obviously questionable. |
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Sets up some foundations for the coming coverage sprint:
cli.App.Metadata)Next steps are roughly:
fmt.*Print*calls and use the appropriate output writer insteadErrorAndExits over to error returns at some pointos.Exit(1)is much more restricting than panics, as it prevents running any defers (for printing or flushing to files) and cannot be checked in tests or suppressed for "attempt or use fallback"I did try to use the
cli.Context.Contextfield for more "normal" dependency injection... but it ended up more annoying.The main issue it that requires using
app.RunContext(populatedContext), but direct access to the*cli.Appexists all over and urfave's API largely requires this. That leaves a rather large hard-to-protect error path, and it takes a few additional awkward lines of code to construct and/or pass it around.With
Metadata, that construction can be done where all the other construction is done: insidecli.App-constructors. And since theMetadatafield is completely ignored by urfave's internals currently, it's basically equivalent but easier.And last but not least: if they do start printing Metadata some day or something, we can switch to context key(s) with relatively minimal fuss since they're both available in the same way in the same locations.