Re: How to make sure some operations in ANY situation? (aka: with statement in Python)
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- Subject: Re: How to make sure some operations in ANY situation? (aka: with statement in Python)
- From: Mark Hamburg <mark@...>
- Date: 2011年6月20日 08:54:27 -0700
local function finish( success, ... )
if not success then
pcall( cleanup ) -- First error wins, so pcall cleanup
error( (...) ) -- May want to play with error level for better reporting
else
cleanup() -- Errors in cleanup would now be interesting
return ...
end
end
return finish( pcall( problem_function ) )
If you never care about errors in cleanup, then you can just always pcall it in the finish function.
Let's take this pattern and use it with files...
local function finish_with_file( f, success, ... )
if not success then
pcall( io.close, f )
error( (...) )
else
io.close( f )
return ...
end
end
function with_file_do( path, fn )
local f = assert( io.open( path ) )
return finish_with_file( f, pcall( fn, f ) )
end
Mark