On 29/10/17 16:45, Alberto Riva wrote:
On 10/29/2017 11:13 AM, bartc wrote:
(What the OP wants was also proposed a few weeks back in comp.lang.c.
But that was only within nested functions, so if H is inside G, and G
is inside F, then a 'returnall' from H would return directly directly
from F. Apparently Lisp allows this...)
Well, not directly, but it can be simulated with the condition system
(equivalent to try/except) or with throw/catch, which is similar but
doesn't use exceptions.
But my point was that in Lisp you don't need to do this, because you can
write a macro that expands into a return *in place*, without calling a
separate function, and this eliminates the problem entirely. Since
Python doesn't have macros I was looking for the next-best solution, but
there doesn't seem to be one. Oh, well...
You can do the same in C. I've had the displeasure of trying to
maintain such code. It was near-unreadable, because it constantly broke
your expectations of what the code flow *could* be. The fact that
something that could return from the middle of your function without the
slightest indication was a rich source of bugs.
(I didn't have to tell my boss to up our rates for dealing with this
code. It took several days to do the work anyway, which was punishment
enough at our rates.)
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Rhodri James *-* Kynesim Ltd
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