[WIP] Allow shorter syntax for tasks with default configuration

[jaedle]

See #194

After doing some coding/research how to implement this, I have a few questions:

1. If I got it right, this is a new feature only for version 3 taskfiles?
2. What should happen if an older version (i.e. version 2) is used with that notation? Should that result in an parsing error? - This would mean like having a switch inside of internal/taskfile/taskfile.go for disallow a shorter syntax for older taskfile versions?
3. Because the unmarshalling has now different source structures (unmarshal from task structure, umarshal an array of strings, unmarshal a string) how should be dealt with the possible errors? I think giving a good error message may be complicated, because we can't guess which synrax should be used. For an approach to unmarshal different types within go-yaml see Parsing array of string or single string go-yaml/yaml#100 (comment)

(I will squash this branch before review)

[andreynering]

Hi @jaedle, thanks for opening this PR!

Regarding 1) and 2), I think would not be a that big deal to allow the shorter syntax on v2, too. (Even then, this should still target the v3 branch). That's what we've been done with other syntax alternatives, too.

That said, if we find a easy/right way to only allow it on v3, it'd be the ideal scenario. If you're unsure about how to do that, it could be pulled to a future fix/PR.

Regarding 3), we already do that for other data structures. In short, what you should do is:

1. If the value is a string slice, assign it to task.Cmds and keep other attributes zeroed/default;
2. The same if the value is a string, just wrap it into a string slice and assign it to task.Cmds.

Does that makes sense?

[andreynering]

Good job so far 👏 👏 👏

I did a suggestion on how to simplify func (t *Task) UnmarshalYAML a bit, though. Hope that makes sense.

[andreynering]

Hey @jaedle,

IMHO you don't need to copy the entire task struct into this function. Just try to marshal the string and []string types first, and none work then unmarshal to the t variable directly. 🙂

[andreynering]

Oops, I just remembered that we also have alternative command syntaxes, like { cmd: "echo foo", silent: true } for example.

That's easy to do, though. Just check for taskfile.Cmd and []taskfile.Cmd instead of for string and []string. All variations should just work.

[andreynering]

Suggested change

[andreynering]

Given the suggestion made on func (t *Task) UnmarshalYAML, we should re-add this reflect tag.

[andreynering]

Hi @jaedle,

I just manually merged your work on v3 with some changes on b7b752b.

Thanks a lot for contributing!