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On 2019-06-20 8:28 p.m., Philipp Janda wrote:
Am 21.06.19 um 00:16 schröbte Soni "They/Them" L.:

local function do_something_with_file(f)
     local <with> f = f -- f:__enter()
     f:write("hello!\n")
     -- f:__close()
end

You shouldn't dispose objects you didn't allocate in any Lua version because the code that did allocate the object might still need it after you have returned. And that makes <toclose>/<with> nesting superfluous.


do_something_with_file(io.open("foo", "w")) -- okay, file gets closed

local <with> f = io.open("bar", "w") -- f:__enter()
do_something_with_file(f) -- doesn't close file
f:write("goodbye!\n")
-- f:__close() -- file gets closed

I was thinking about this:

local f = io.open("bar", "w")
do_something_with_file(f) -- closes file
f:write("goodbye!\n") -- error


Philipp




my point is <toclose> could be an option to support nested contexts. in addition to plain old :close() that only does unnested contexts. it would be useful because you'd have two ways to use the same function. it improves code reuse and thus improves readability and maintainability!

in other words: benefits all around!