Use format = "file" instead of tar_file

[multimeric]

Happy to discuss the merits of this. Basically I've found myself preferring to use tar_target(format = "file") instead of tar_file. My motivations for this are:

• Doesn't require a dependency
• Starts passively teaching people about formats and the format argument, which they can later explore themselves
• Would let us remove tarchetypes dependency completely if we also stop using tar_file_read (see: https://github.com/carpentries-incubator/targets-workshop/issues/22).

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:stopwatch: Updated at 2024-07-10 05:54:32 +0000

[joelnitta]

Thanks for the PR @multimeric !

I think this is related to a broader discussion of design philosophy of the lesson: should we use syntactic sugar to make the pipeline look nicer (and perhaps more like what a learner is likely to encounter in the wild), or stick to a limited number of more verbose functions to hopefully foster better learner comprehension? I think the best approach may be to use some of both. I freely admit my opinion on how much of each is biased by my personal preferences when writing {targets} pipelines.

For example, I agree that tar_file_read() should be removed (#42), particularly because of the NSE needed to make it work (!!.x).

However, I just taught the workshop myself again recently, and had no problem with tar_plan(). It probably took <10 min to explain, and I think its syntax does make the dependency relationship between targets clearer. IMHO it is worth emphasizing that a {targets} workflow (list() or tar_plan()) should be written as a high-level description of the workflow that can be understood even without knowing the details of {targets}. tar_plan() goes a pretty far way towards that.

tar_file() is somewhat in the middle. I don't think it is asking much of learners since it can be used as a drop-in for tar_target(), but on the other hand, it is also straightforward to add format = "file" to tar_target().

{tarchetypes} is also needed for tar_quarto(), which I definitely think should be kept, so we won't be dropping that dependency. Also, I think it's also good for learners to be aware of {tarchetypes} and what it is used for.