Duncan Booth wrote : > francois.petitjean at bureauveritas.com wrote: >> After much head scrating and experimenting with dis.dis() I have found >> that chaining comparisons (with is or ==) a == b == c in Python is >> never a good idea. It is interpreted as >> ( a == b ) and ( b == c) >> Such a magic is fine when we write: >> if 0.0 <= x < 1.0: >> but it renders the outcome of if a == b == c: somewhat confusing.
> I don't understand why it is confusing. What other meaning would you > expect? Consider: >>> Python = cool = True >>> Python is cool True >>> Python is cool is True True # heh it seems possible to tackle is True to a boolean expression (not always) >>> it = False >>> Python is cool is not it True # I knew that. slef evident... >>> Python = cool = False >>> Python is cool is not it False # Waht? desillution... # Ough! You must reread the reference documentation on chaining the comparison operators and understand the semantics (the two comparisons are 'anded' and 'and' shortcircuits in Python). >>> Python is cool True # Yeah! Regards NOTICE: This message contains information which is confidential and the copyright of our company or a third party. If you are not the intended recipient of this message please delete it and destroy all copies. If you are the intended recipient of this message you should not disclose or distribute this message to third parties without the consent of our company. Our company does not represent, warrant and/or guarantee that the integrity of this message has been maintained nor that the communication is free of virus, interception or interference. The liability of our company is limited by our General Conditions of Services. Nota : Ce message contient des informations confidentielles propriété de notre société et/ou d'un tiers. Si vous n'êtes pas parmi les destinataires désignés de ce message, merci de l'effacer ainsi que toutes ses copies. Si vous êtes parmi les destinataires désignés de ce message, prière de ne pas le divulguer ni de le transmettre à des tiers sans l'accord de notre société. Notre société ne peut garantir que l'intégrité de ce message a été préservée ni que la présente communication est sans virus, interception ou interférence. La responsabilité de notre société est limitée par nos Conditions Générales de Services. -- http://mail.python.org/mailman/listinfo/python-list
