Method definition on record imported from declaration file does not throw an error? about tl HOT 7 CLOSED

This is a little tricky. It allows declaring functions over unknown keys of records to support this:

local my_module = {}

function my_module.my_function()
   -- ...
end

...which is a super common pattern.

What you might be suggesting is that function t.unknown_key should work differently whether the table is declared in the same file or required from a different one (or perhaps it should be a matter of scope levels instead). In any case, it's an intriguing idea.

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Perhaps there should be an alternative record declaration syntax that forces you to declare all fields upfront? Something like this:

declare global love = record -- I'm not a fan of this 'declare' keyword... maybe you have a better idea?
	draw: function()
end

function love.draw() -- this works, since the `draw` key is known
	print("draw stuff...")
end

function love.draws() -- error: unknown key 'draws' in 'love'
	print("draw stuff...")
end

I think this feature would be useful for declaration files, since I don't think we typically want to "extend" the definitions outside of the initial record declaration.

from tl.

@pdesaulniers I made it in #48 so that it decides by scope whether it's ok or not to create a new function, the PR contains a description (and so do the tests), check it out!

from tl.

OK, that works!

I guess this behavior might seem a bit surprising for newcomers. Personally, I would expect global records to behave the same way as local records.

But then, I think it's fine for now. Global variables should generally be avoided anyway :)

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I agree, but then either love.draws would have to be accepted, or people would be forced to pre-declare every function in their module. At least I think I managed to produce a reasonable error message that explains the situation. At one point I'd like to do what the Rust compiler does and put "pointers" in the error messages such as error code numbers, that people can easily search online and reach an explanation that's longer than one line.

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Yep. This could be mentioned in the docs.

I think this behavior is fine for the time being.

from tl.

Yeah, will definitely document it... when I get around to start the documentation! Which should probably be the next thing for me to work on!

Going to merge the PR and close this one, thanks for bouncing ideas :)

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