Generate structs from schema

[pedromss]

@nrwiersma here's a sample of what the generation feature could be, let me know what you think.

Considerations:

• I avoided touching any existing code, so there might be somethings that are are better placed elsewhere or already exist
• RefSchema isn't handled yet, understanding it first
• Pulled in dst for some comodity when printing

If the core looks ok, we could discuss which options the generator should support (other tags like json or different casing for example) and where to place it. Usually code generation runs as part of my build phase, so I'd expect a command line utility to be the interface for this feature, open to suggestions.

The generation can be done in a separate repo, but keeping them together might reduce the possibility of a change in the core lib (some change in the Schema interface for example) breaking the generator.

You can run TestGenFromRecordSchema and see the result as that test is currently printing the Go code

TODO:

• Casing in package name
• Adding the imports to the generated file
• Support RefSchema

Future possible improvements

• Generating functions to register types (I think this one is interesting as it would remove the need to manually call avro.Register)

Thoughts on avro use cases not covered in the test are welcome (aside from the RefSchema)

#119 (comment)

[nrwiersma]

Wow, this looks awesome. I am hoping to have some time to dig into it this weekend.

To answer one question off the top of my head, I think there should be a cmd but also it should be usable as a lib. I have personally used both types in code, and in the CI when getting the cmd can be a pain and an extra step, using the lib from an internal cmd is much simpler.

[pedromss]

Thank you.

After you've looked into this, it looks good, I think the step to move out of draft could be:

• Figure out which options make sense in GenConf
• Implement an behaviour required for the options
• Implement the CLI (would need to know where you would like the cmd as I don't see a cmd folder which is where I'm used to see binaries

If after you've looked into this you feel like its not worth adding this to hamba/avro also no worries, feel free to dismiss :)

I had thought about generating the avro.Register calls, but I think that could come in another PR.

I've never used "internal cmds" I think, but if that means we can defer the CLI to a separate PR, maybe that's better, up to you

[nrwiersma]

Firstly, awesome work 🎉 . I have added some suggestions and thoughts. In general I think this is on an amazing track.

[pedromss]

Added a few commits to address the comments. Thinking on adding now:

1. Option to add more tags, like json and their casing
2. CLI interface

But let me know if you have more things to be addressed first.

[pedromss]

Noticed the actions failed. I was trying to run make build, test, lint locally but I get Makefile:1: github.com/hamba/make/golang.mk: No such file or directory. I've never used make with include so I'm not sure if I need to install something else for it to be able to resolve the include directive.

[nrwiersma]

It is using mmake for the include (https://github.com/tj/mmake). Honestly I dont use it so much any more. Think i need to get rid of it.

[pedromss]

Installed gofumpt and fixed the failures + warnings in the action, in case you want to run it again

[nrwiersma]

I would personally be happy to merge this here and do the rest as additional PRs. What do you think?

[pedromss]

Sounds good. I'll add a few tests for the failure cases and that should make coveralls happy

[nrwiersma]

After this merge I will sort out the Makefile and rebase on master.

[nrwiersma]

Minor nitpick: Could this perhaps be Config rather?

[pedromss]

When ready to merge let me know if you prefer I squash all commits into 1

[nrwiersma]

LGTM 🎉

[nrwiersma]

Merging now as is.