This is *exactly* what Python does right now!

class ToFailError(Exception): pass

try:

do_some_stuff()

if (some_error):

raise ToFailError

do_other_stuff()

try:

thing_that_might_fail()

except SomeOtherError:

handle_it()

except ToFailError:

here_we_are()

On Wed, Mar 5, 2014 at 7:54 PM, Sturla Molden <sturla.molden@gmail.com> wrote:

"goto fail" is a well-known error handling mechanism in open source software, widely reputed for its robusteness:

http://opensource.apple.com/source/Security/Security-55471/libsecurity_ssl/lib/sslKeyExchange.c

https://www.gitorious.org/gnutls/gnutls/source/6aa26f78150ccbdf0aec1878a41c17c41d358a3b:lib/x509/verify.c

I believe Python needs to add support for this superior paradigm.

It would involve a new keyword "fail" and some means of goto'ing to it. I suggest "raise to fail":

if (some_error):
raise to fail

fail:
<error handling code>

Unless there are many objections, this fantastic idea might be submitted in a (short) PEP somewhere around the beginning of next month.

There is some obvious overlap with the rejected "goto PEP" (PEP 3163) and the Python 2.3 goto module. However, the superiority of goto fail as error generation and error handling paradigm has since then been thoroughly proven.

http://legacy.python.org/dev/peps/pep-3136/
http://entrian.com/goto/download.html

Regards,
Sturla Molden

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