Re: Non Local Exits: Some usage notes
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- Subject: Re: Non Local Exits: Some usage notes
- From: Mark Hamburg <mhamburg@...>
- Date: 2005年8月12日 15:33:51 -0700
Nice notes on the usage of non-local exits. I should go back and re-read
more of the Dylan material sometime.
I will note that the big win in general is using finally to provide an
approach to writing wrappers that doesn't hurt one's head. Contrast:
function do_with_lock( lock, fn, ... )
lock:lock()
return fn( ... )
finally
lock:unlock()
end
(Blocks elided here.)
With what one has to write today:
function pcall2call( success, ... )
if success then
return ...
else
error( ..., 0 )
end
end
function unlocker( lock, ... )
lock:unlock()
return pcall2call( ... )
end
function do_with_lock( lock, fn, ... )
lock:lock()
return unlocker( lock, pcall( fn, ... ) ) )
end
Mark