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How to implement __iter__(self) for a container object (Python)
... to the sequence.
The following will create an iterator that yields five, and then every item in some_list.
def __iter__(self):
yield 5
yield from some_list
Pre-3.3, yield from didn't exist, so you would have to do:
def __iter__(self):
yield 5
for x in some_list:
yield x
...
Is it possible to print a variable's type in standard C++?
... update to a very old question: Print variable type in C++.
The accepted (and good) answer is to use typeid(a).name(), where a is a variable name.
Now in C++11 we have decltype(x), which can turn an expression into a type. And decltype() comes with its own set of very interesting rules. For exam...
What would a “frozen dict” be?
...self._d[key]
def __hash__(self):
# It would have been simpler and maybe more obvious to
# use hash(tuple(sorted(self._d.iteritems()))) from this discussion
# so far, but this solution is O(n). I don't know what kind of
# n we are going to run into, but sometime...
How to make a class property? [duplicate]
... in self.__dict__:
obj = self.__dict__.get(key)
if obj and type(obj) is ClassPropertyDescriptor:
return obj.__set__(self, value)
return super(ClassPropertyMetaClass, self).__setattr__(key, value)
# and update class define:
# class Bar(object):
# _...
Calling class staticmethod within the class body?
When I attempt to use a static method from within the body of the class, and define the static method using the built-in staticmethod function as a decorator, like this:
...
How to make a class JSON serializable
...you want more customized output then you will have to subclass JSONEncoder and implement your own custom serialization.
For a trivial example, see below.
>>> from json import JSONEncoder
>>> class MyEncoder(JSONEncoder):
def default(self, o):
return o.__dict_...
How can I get the version defined in setup.py (setuptools) in my package?
...o have thought you were asking), put the version string in a separate file and read that file's contents in setup.py.
You could make a version.py in your package with a __version__ line, then read it from setup.py using execfile('mypackage/version.py'), so that it sets __version__ in the setup.py n...
Python hashable dicts
As an exercise, and mostly for my own amusement, I'm implementing a backtracking packrat parser. The inspiration for this is i'd like to have a better idea about how hygenic macros would work in an algol-like language (as apposed to the syntax free lisp dialects you normally find them in). Because...
Difference between Python's Generators and Iterators
What is the difference between iterators and generators? Some examples for when you would use each case would be helpful.
1...
How to add property to a class dynamically?
...
I suppose I should expand this answer, now that I'm older and wiser and know what's going on. Better late than never.
You can add a property to a class dynamically. But that's the catch: you have to add it to the class.
>>> class Foo(...