On 13/04/2017 15:35, Chris Angelico wrote:
On Thu, Apr 13, 2017 at 9:31 PM, alister <alister.w...@ntlworld.com> wrote:
I expect you could simulate most of these with a custom exception
for example break from nested loop:
class GoTo(Exception):
pass
try:
for i in range(100):
print i
for j in range (50):
print j
if i*j>60:
raise GoTo
except GoTo:
print "Exit Early"
print "end of loop"
Or you could turn it into a function and "return". Or if you feel like
it, you could turn the nested loops into a generator, then iterate
over it and break when you need to.
I know this isn't the Python need-for-speed thread, but this is a
classic example where the lack of one simple feature leads to using
slower, more cumbersome ones.
'goto' would be one easy-to-execute byte-code; no variables, objects or
types to worry about. If implemented properly (with the byte-code
compiler using a dedicated name-space for labels) there would be no name
lookups.
Function calls, returns and generators are rather more heavyweight in
comparison.
There are many things you CAN do,
but to the true goto-aficionado, none of them is as clean.
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.
It might be a better idea to have a multi-level loop break then. This
would also be an absolute jump byte-code.
--
bartc
--
https://mail.python.org/mailman/listinfo/python-list
