On 04/13/2017 08:26 AM, Marko Rauhamaa wrote:
Chris Angelico <ros...@gmail.com>:
Personally, I can't remember the last time I yearned for "goto" in
Python, and the only times I've ever wished for it or used it in other
languages have been multi-loop breaks or "for...else" blocks. And
neither is very frequent.
I have occasionally felt the urge to try "goto" in my C code, but having
written it, I have taken it out. It just doesn't make the code look more
elegant or robust. Unlike "break" or "return," "goto" makes me uneasy
about variable scope and lifetime.
Maybe it would work in some state machine implementation. Some 30 years
ago I wrote a compiler. The parser came out nicer with methodical use of
"goto," but even then, I used a parsing-specific macro to wrap it.
Marko
You see it all the time in kernel code or when doing I/O. A pretty
common pattern is:
int return_val = 1;
if (init_thing(x)) goto bk1;
if (init_thing(y)) goto bk2;
if (init_thing(z)) goto bk3;
do_things_with(x, y, z);
return_val = 0;
bk3: cleanup_thing(z);
bk2: cleanup_thing(y);
bk1: cleanup_thing(x);
return return_val;
But the point is, in Python we have context managers and exceptions and
classes, all of which serve to allow you to not have to explicitly lay
out how to wind yourself step-by-step back out of the situation you've
gotten yourself into.
--
Rob Gaddi, Highland Technology -- www.highlandtechnology.com
Email address domain is currently out of order. See above to fix.
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