"print" on tables skips __tostring on table types, while it supports it for light userdata types

[HealthyKarl]

Description

This is how Userdata with __tostring appears, when using print on a table, where the object is put as the key.

Like so:

print({
    [object_here] = "value"
})

However, tables have this skipped.

Re-production steps

1. Run this in Studio

local object = newproxy(true)
getmetatable(object).__tostring = function()
	return "__tostring from userdata"
end

local object2 = setmetatable({}, {
	__tostring = function()
		return "__tostring from table"
	end,
})


print("Userdata __tostring:", object)
print("Table __tostring:", object2)

print({
	[object] = "userdata test",
	[object2] = "table test"
})

2. Observe the Output Window

Expected Result

I expected this part

to use the corresponding __tostring as well, but it didn’t

If __tostring is declared on a metatable of a table, I expected the pretty print to use __tostring.

Actual Result

__tostring from newproxy’s modified metatable was used. But the one from the actual table wasn’t used.

[thirdtakeonit]

Thanks for the report! I filed a ticket in our internal database.

[WheretIB]

We have prepared a fix for this issue.
We will post an update after it’s released.

[HealthyKarl]

When did Roblox Studio change in what order the table prints out as?

local tbl = {
	["c"] = "test",
	["a"] = "test"
}

print(tbl)
for k,v in pairs(tbl) do print(k,v) end

I just noticed this after running the above code for the re-production steps.

Why is Roblox Studio sorting its own print table alphabetically now?

[HealthyKarl]

Looks like the fix is out, is it true? And this looks to be fixed now, as the Re-production steps example now run the __tostring

 

I am wondering about this though.

@HealthyKarl

When did Roblox Studio change in what order the table prints out as?

local tbl = {
	["c"] = "test",
	["a"] = "test"
}

print(tbl)
for k,v in pairs(tbl) do print(k,v) end

I just noticed this after running the above code for the re-production steps.

Why is Roblox Studio sorting its own print table alphabetically now?

[WheretIB]

The fix for the issue has been released.

@HealthyKarl

I am wondering about this though.

I don’t work on Studio output, but sorting was supported since 2021.

[HealthyKarl]

oh I think it’s because of the __ in my repro compared to the screenshot I took for the actual result, yeah I got confused, I think it’s fine

Very cool, thanks for the fix!