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Difference between len() and .__len__()?
Is there any difference between calling len([1,2,3]) or [1,2,3].__len__() ?
4 Answers
...
Inherit docstrings in Python class inheritance
...out this a while ago, and a recipe was created. Check it out here.
"""
doc_inherit decorator
Usage:
class Foo(object):
def foo(self):
"Frobber"
pass
class Bar(Foo):
@doc_inherit
def foo(self):
pass
Now, Bar.foo.__doc__ == Bar().foo.__doc__ == Foo.foo.__doc__...
How to get name of exception that was caught in Python?
...rent ways to get the name of the class of the exception:
type(exception).__name__
exception.__class__.__name__
exception.__class__.__qualname__
e.g.,
try:
foo = bar
except Exception as exception:
assert type(exception).__name__ == 'NameError'
assert exception.__class__.__name__ == '...
Accessing class variables from a list comprehension in the class definition
...(1)]
... return Foo
...
>>> dis.dis(foo)
2 0 LOAD_BUILD_CLASS
1 LOAD_CONST 1 (<code object Foo at 0x10a436030, file "<stdin>", line 2>)
4 LOAD_CONST 2 ('Foo')
7 MAKE_FUNCTION ...
Create a custom event in Java
...else in the package
interface ThrowListener {
public void Catch();
}
/*_____________________________________________________________*/class Thrower {
//list of catchers & corresponding function to add/remove them in the list
List<ThrowListener> listeners = new ArrayList<ThrowLis...
What does __FILE__ mean in Ruby?
...
It is a reference to the current file name. In the file foo.rb, __FILE__ would be interpreted as "foo.rb".
Edit: Ruby 1.9.2 and 1.9.3 appear to behave a little differently from what Luke Bayes said in his comment. With these files:
# test.rb
puts __FILE__
require './dir2/test.rb'
# di...
Why is “if not someobj:” better than “if someobj == None:” in Python?
...r not ? This is done using the following algorithm :
If the object has a __nonzero__ special method (as do numeric built-ins, int and float), it calls this method. It must either return a bool value which is then directly used, or an int value that is considered False if equal to zero.
Otherwise, ...
How to get a complete list of object's methods and attributes?
...nts accepted by the getattr built-in function. As the user can reimplement __getattr__, suddenly allowing any kind of attribute, there is no possible generic way to generate that list. The dir function returns the keys in the __dict__ attribute, i.e. all the attributes accessible if the __getattr__ ...
Standard alternative to GCC's ##__VA_ARGS__ trick?
...
It is possible to avoid the use of GCC's ,##__VA_ARGS__ extension if you are willing to accept some hardcoded upper limit on the number of arguments you can pass to your variadic macro, as described in Richard Hansen's answer to this question. If you do not want to hav...
Getting attributes of a class
...gt;> inspect.getmembers(MyClass, lambda a:not(inspect.isroutine(a)))
[('__class__', type),
('__dict__',
<dictproxy {'__dict__': <attribute '__dict__' of 'MyClass' objects>,
'__doc__': None,
'__module__': '__main__',
'__weakref__': <attribute '__weakref__' of 'MyClass' obje...