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--
-- Test resource cleanup
--
-- This feature was ... by discussion on the Lua list about exceptions.
-- The idea is to always run a certain block at exit, whether due to success
-- or error. Normally, 'pcall' would be used for such but as Lua already
-- does that, simply giving a 'cleanup=function' parameter is a logical
-- thing to do. -- AKa 22-Jan-2009
--
require "lanes"
local FN= "finalizer-test.tmp"
local cleanup
local which= os.time() % 2 -- 0/1
local function lane()
set_finalizer(cleanup)
local f,err= io.open(FN,"w")
if not f then
error( "Could not create "..FN..": "..err )
end
f:write( "Test file that should get removed." )
io.stderr:write( "File "..FN.." created\n" )
if which==0 then
error("aa") -- exception here; the value needs NOT be a string
end
-- no exception
end
--
-- This is called at the end of the lane; whether succesful or not.
-- Gets the 'error()' parameter as parameter ('nil' if normal return).
--
cleanup= function(err)
-- An error in finalizer will override an error (or success) in the main
-- chunk.
--
--error( "This is important!" )
if err then
io.stderr:write( "Cleanup after error: "..tostring(err).."\n" )
else
io.stderr:write( "Cleanup after normal return\n" )
end
local _,err2= os.remove(FN)
assert(not err2) -- if this fails, it will be shown in the calling script
-- as an error from the lane itself
io.stderr:write( "Removed file "..FN.."\n" )
end
local lgen = lanes.gen("*", lane)
io.stderr:write "Launching the lane!\n"
local h= lgen()
local _,err,stack= h:join() -- wait for the lane (no automatic error propagation)
if err then
assert(stack)
io.stderr:write( "Lane error: "..tostring(err).."\n" )
io.stderr:write( "\t", table.concat(stack,"\t\n"), "\n" )
end
local f= io.open(FN,"r")
if f then
error( "CLEANUP DID NOT WORK: "..FN.." still exists!" )
end
io.stderr:write "Finished!\n"
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