Re: Proposed new conditional operator: "or else"
On Wed, Dec 3, 2014 at 10:59 PM, Tim Chase wrote: > On 2014-12-02 23:05, Dennis Lee Bieber wrote: >> > foo == 42 or else >> >> Has a PERL stink to it... like: foo == 42 or die > > This statement actually works in Python and I occasionally use it > when debugging (in the same fashion as one might do printf() > debugging in C). It raises a NameError and the program dies with a > traceback. Most frequently, it's to prevent the program from > continuing on to connect to a database and actually make changes. *gasp* But it's just as fragile as assert! Anyone could just put one line of code into your program and destroy all your debugging checks! die = False Your code has just been made immortal! This is *obviously* a complete waste of time, since it's that easy to defeat! > [sorry for the previous message if I failed to cancel the send that > happened when I accidentally pressed ctrl+enter...typing in the dark] It was its own joke. :) ChrisA -- https://mail.python.org/mailman/listinfo/python-list
Re: Proposed new conditional operator: "or else"
On 2014-12-02 23:05, Dennis Lee Bieber wrote: > > foo == 42 or else > > Has a PERL stink to it... like: foo == 42 or die This statement actually works in Python and I occasionally use it when debugging (in the same fashion as one might do printf() debugging in C). It raises a NameError and the program dies with a traceback. Most frequently, it's to prevent the program from continuing on to connect to a database and actually make changes. I've grown up a bit and usually use pdb.set_trace() now, but it's still in my grab-bag of tools. -tkc [sorry for the previous message if I failed to cancel the send that happened when I accidentally pressed ctrl+enter...typing in the dark] -- https://mail.python.org/mailman/listinfo/python-list
Re: Proposed new conditional operator: "or else"
On Wed, Dec 3, 2014 at 10:56 PM, Tim Chase wrote: > This actually works in Python and I occasionally use in debugging > (much like finish_sentence() or die ChrisA -- https://mail.python.org/mailman/listinfo/python-list
Re: Proposed new conditional operator: "or else"
On 2014-12-02 23:05, Dennis Lee Bieber wrote: > > foo == 42 or else > > Has a PERL stink to it... like: foo == 42 or die This actually works in Python and I occasionally use in debugging (much like -- https://mail.python.org/mailman/listinfo/python-list
Re: Proposed new conditional operator: "or else"
Dennis Lee Bieber wrote: >> foo == 42 or else >> > > Has a PERL stink to it... like: foo == 42 or die I think this statement needs to take ellipsis as well foo == 42 or else ... Sturls -- https://mail.python.org/mailman/listinfo/python-list
Re: Proposed new conditional operator: "or else"
On 12/02/2014 10:18 AM, Roy Smith wrote: > In the process of refactoring some code, I serendipitously created what I > think is an essential new bit of Python syntax. The “or else” statement. I > ended up with: > > sites_string = args.sites or else self.config['sites'] But isn't that syntactically equivalent of this? sites_string = args.sites or self.config['sites'] Seems to be what you're looking for with "or else" unless I misunderstand what you're proposing. Doing a bit of testing in the interpreter and I find that a combination of Python's truthiness semantics and short-circuit evaluation seems to give a consistent result. Consider: 'a word' or False => 'a word' 'a word' or True => 'a word' False or 'a word' => 'a word' True or 'a word' => True Is this similar to what you'd expect with "or else?" -- https://mail.python.org/mailman/listinfo/python-list
Re: Proposed new conditional operator: "or else"
In article , Chris Angelico wrote: > On Wed, Dec 3, 2014 at 4:41 AM, Zachary Ware > wrote: > > On Tue, Dec 2, 2014 at 11:18 AM, Roy Smith wrote: > >> Wouldnât it be neat to write: > >> > >>foo == 42 or else > >> > >> and have that be an synonym for: > >> > >> assert foo == 42 > >> > >> :-) > > > > Never going to happen, but I like it! Perhaps raise IntimidationError > > instead of AssertionError when it fails? > > Definitely. That's what I first thought, when I saw the subject line. > > Additionally, whenever this construct is used, the "yield" statement > (expression, whatever) will be redefined to yield to intimidation and > make the statement true, whatever it takes. In the above example, > "yield" would decide which out of foo and 42 is more amenable to > change, and altering it to be equal to the other. (It may also find > that == is the most amenable, and alter its definition such that foo > and 42 become equal.) > > ChrisA This could be handy in the field of forensic accounting. -- https://mail.python.org/mailman/listinfo/python-list
Re: Proposed new conditional operator: "or else"
Zachary Ware wrote: > On Tue, Dec 2, 2014 at 11:18 AM, Roy Smith wrote: >> Wouldn’t it be neat to write: >> >>foo == 42 or else >> >> and have that be an synonym for: >> >> assert foo == 42 >> >> :-) > > Never going to happen, but I like it! Perhaps raise IntimidationError > instead of AssertionError when it fails? I guess the "or else" statement should do this: or else where the statement is executed if the statement evaluates to false. In absence of an explicit threat or else it should raise IntimidationError if evaluates to false false. If evaluates to true it should just return . Sturla -- https://mail.python.org/mailman/listinfo/python-list
Re: Proposed new conditional operator: "or else"
On 2014-12-02 17:41:06 +, Zachary Ware said: foo == 42 or else Never going to happen, but I like it! Perhaps raise IntimidationError instead of AssertionError when it fails? That should probably be a DONTPANICError in large, friendly terminal font letters. -- Andrea -- https://mail.python.org/mailman/listinfo/python-list
Re: Proposed new conditional operator: "or else"
Tim Chase : >> >foo == 42 or else > > In light of the parallel thread discussing the "assert" statement and > the perils of trusting it to be present even though it can be > optimized away, this "or else" could be (in the altered words of Don > Corleone), "I'm gonna make an assertion he can't refuse." I would consider vain threats an antipattern. Marko -- https://mail.python.org/mailman/listinfo/python-list
Re: Proposed new conditional operator: "or else"
On 2014-12-02 11:41, Zachary Ware wrote: > On Tue, Dec 2, 2014 at 11:18 AM, Roy Smith wrote: > > Wouldn’t it be neat to write: > > > >foo == 42 or else > > > > and have that be an synonym for: > > > > assert foo == 42 > > > > :-) > > Never going to happen, but I like it! Perhaps raise > IntimidationError instead of AssertionError when it fails? In light of the parallel thread discussing the "assert" statement and the perils of trusting it to be present even though it can be optimized away, this "or else" could be (in the altered words of Don Corleone), "I'm gonna make an assertion he can't refuse." (not that I particularly want/expect this in the language definition, but it's fun to entertain the idea) -tkc -- https://mail.python.org/mailman/listinfo/python-list
Re: Proposed new conditional operator: "or else"
On Wed, Dec 3, 2014 at 4:41 AM, Zachary Ware wrote: > On Tue, Dec 2, 2014 at 11:18 AM, Roy Smith wrote: >> Wouldn’t it be neat to write: >> >>foo == 42 or else >> >> and have that be an synonym for: >> >> assert foo == 42 >> >> :-) > > Never going to happen, but I like it! Perhaps raise IntimidationError > instead of AssertionError when it fails? Definitely. That's what I first thought, when I saw the subject line. Additionally, whenever this construct is used, the "yield" statement (expression, whatever) will be redefined to yield to intimidation and make the statement true, whatever it takes. In the above example, "yield" would decide which out of foo and 42 is more amenable to change, and altering it to be equal to the other. (It may also find that == is the most amenable, and alter its definition such that foo and 42 become equal.) ChrisA -- https://mail.python.org/mailman/listinfo/python-list
Re: Proposed new conditional operator: "or else"
On 12/02/2014 09:41 AM, Zachary Ware wrote: > On Tue, Dec 2, 2014 at 11:18 AM, Roy Smith wrote: >> >> Wouldn’t it be neat to write: >> >>foo == 42 or else >> >> and have that be an synonym for: >> >> assert foo == 42 > > Never going to happen, but I like it! Perhaps raise IntimidationError > instead of AssertionError when it fails? As long as when raising Intimidation, it also roughs up a couple surrounding lines as a warning to the rest of the code... -- ~Ethan~ signature.asc Description: OpenPGP digital signature -- https://mail.python.org/mailman/listinfo/python-list
Re: Proposed new conditional operator: "or else"
On Tue, Dec 2, 2014 at 11:18 AM, Roy Smith wrote: > Wouldn’t it be neat to write: > >foo == 42 or else > > and have that be an synonym for: > > assert foo == 42 > > :-) Never going to happen, but I like it! Perhaps raise IntimidationError instead of AssertionError when it fails? -- Zach -- https://mail.python.org/mailman/listinfo/python-list
