7 ms·

Python 3 removed this feature unfortunately.

by rectangletangle 11y ago

tdicola 11y ago
Unfortunately? I'd love to know when changing false to mean true and vice-versa would make sense in any codebase.
rectangletangle 11y ago
>>> (False, True) = (True, False) >>> 1 if False else 0 1 >>> bool(0) == False False
- janzer 11y ago
  Not entirely sure of your point but... Python 3.4.0 (default, Apr 11 2014, 13:05:11) [GCC 4.8.2] on linux Type "help", "copyright", "credits" or "license" for more information. >>> (True, False) = (False, True) File "<stdin>", line 1 SyntaxError: can't assign to keyword
- exogen 11y ago
  But, like the parent said, in Python 3: >>> (False, True) = (True, False) File "<stdin>", line 1 SyntaxError: can't assign to keyword
- thaumasiotes 11y ago
  In[2]: (True, False) = (False, True) In[3]: True Out[3]: False In[4]: 1 if False else 0 Out[4]: 1 In[5]: 'yes' if bool(0) == False else 'no' Out[5]: 'no' In[6]: bool(0) == False Out[6]: False What bothers me here is that when the interpreter says "False", it clearly means the opposite of (the new) False. So by reassigning True and False, I've actually caused inconsistent behavior in python, not just really-confusingly-named behavior. Suddenly False sometimes means one thing and sometimes means something else.
  - masklinn 11y ago
    There's no inconsistency, the "False" printed in your console is just the repr of the object, you can give that repr to your own object if you have nothing better to do with your life: >>> A() False >>> bool(A()) True >>> type(A()) <class '__main__.A'> A repr is just a representation in development context, nothing more and nothing less, there is no requirement that it be sensible or of any use, though that's certainly recommended (contrary to __str__/__unicode__ which should be silly): >>> B() A gray parrot The only "inconsistency" you've created is that False in the console's local namespace does not match __builtins__.False or the interpreter's internal False object. You can still access the former by the way: >>> False True >>> __builtins__.False False unless you also override it: >>> __builtins__.False = True >>> __builtins__.False True the interpreter still does not care though, you've just broken any Python code relying on the builtin (you can actually alter the "true" False object via ctypes)

Python 3 removed this feature unfortunately.

tdicola 11y ago

Unfortunately? I'd love to know when changing false to mean true and vice-versa would make sense in any codebase.

rectangletangle 11y ago

>>> (False, True) = (True, False) >>> 1 if False else 0 1 >>> bool(0) == False False

janzer 11y ago
Not entirely sure of your point but... Python 3.4.0 (default, Apr 11 2014, 13:05:11) [GCC 4.8.2] on linux Type "help", "copyright", "credits" or "license" for more information. >>> (True, False) = (False, True) File "<stdin>", line 1 SyntaxError: can't assign to keyword
exogen 11y ago
But, like the parent said, in Python 3: >>> (False, True) = (True, False) File "<stdin>", line 1 SyntaxError: can't assign to keyword
thaumasiotes 11y ago
In[2]: (True, False) = (False, True) In[3]: True Out[3]: False In[4]: 1 if False else 0 Out[4]: 1 In[5]: 'yes' if bool(0) == False else 'no' Out[5]: 'no' In[6]: bool(0) == False Out[6]: False What bothers me here is that when the interpreter says "False", it clearly means the opposite of (the new) False. So by reassigning True and False, I've actually caused inconsistent behavior in python, not just really-confusingly-named behavior. Suddenly False sometimes means one thing and sometimes means something else.
- masklinn 11y ago
  There's no inconsistency, the "False" printed in your console is just the repr of the object, you can give that repr to your own object if you have nothing better to do with your life: >>> A() False >>> bool(A()) True >>> type(A()) <class '__main__.A'> A repr is just a representation in development context, nothing more and nothing less, there is no requirement that it be sensible or of any use, though that's certainly recommended (contrary to __str__/__unicode__ which should be silly): >>> B() A gray parrot The only "inconsistency" you've created is that False in the console's local namespace does not match __builtins__.False or the interpreter's internal False object. You can still access the former by the way: >>> False True >>> __builtins__.False False unless you also override it: >>> __builtins__.False = True >>> __builtins__.False True the interpreter still does not care though, you've just broken any Python code relying on the builtin (you can actually alter the "true" False object via ctypes)