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if A vs if A is not None:
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The statement
if A:
will call A.__nonzero__() (see Special method names documentation) and use the return value of that function. Here's the summary:
object.__nonzero__(self)
Called to implement truth value testing and the built-in operation ...
Method Resolution Order (MRO) in new-style classes?
...ject'>)
with A forced to come in resolution order only once and after all of its subclasses, so that overrides (i.e., C's override of member x) actually work sensibly.
It's one of the reasons that old-style classes should be avoided: multiple inheritance with "diamond-like" patterns just doesn...
Multiple Models in a single django ModelForm?
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But how? Usually a FormView only has a single form_class assigned to it.
– erikbwork
Oct 7 '16 at 17:42
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How to make a chain of function decorators?
...her object
scream = shout
# Notice we don't use parentheses: we are not calling the function,
# we are putting the function "shout" into the variable "scream".
# It means you can then call "shout" from "scream":
print(scream())
# outputs : 'Yes!'
# More than that, it means you can remove the old...
javascript: Clear all timeouts?
Is there a way to clear all time outs from a given window? I suppose the timeouts are stored somewhere in the window object but couldn't confirm that.
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How to clear the interpreter console?
Like most Python developers, I typically keep a console window open with the Python interpreter running to test commands, dir() stuff, help() stuff , etc.
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How update the _id of one MongoDB Document?
I want update an _id field of one document. I know it's not a really good pratice. But with some technical reason, I need update it. If I try to update it I get:
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Which characters are valid in CSS class names/selectors?
What characters/symbols are allowed within the CSS class selectors?
I know that the following characters are invalid , but what characters are valid ?
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Why does GCC generate 15-20% faster code if I optimize for size instead of speed?
... gcc-4.8 1.53s 1.52s -Os
In some cases you can alleviate the effect of disadvantageous optimizations by asking gcc to optimize for your particular processor (using options -mtune=native or -march=native):
Processor Compiler Time (-O2 -mtune=native) Time (-Os...
Regex to Match Symbols: !$%^&*()_+|~-=`{}[]:";'?,./
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The regular expression for this is really simple. Just use a character class. The hyphen is a special character in character classes, so it needs to be first:
/[-!$%^&*()_+|~=`{}\[\]:";'<>?,.\/]/
You also need to escape the other regular expressio...