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What are “first class” objects?
...as
any other object.
A first class object is an entity that can be dynamically created, destroyed, passed to a function, returned as a value, and have all the rights as other variables in the programming language have.
Depending on the language, this can
imply:
being expressible as ...
Compare object instances for equality by their attributes
...s:
>>> x == y
True
Note that implementing __eq__ will automatically make instances of your class unhashable, which means they can't be stored in sets and dicts. If you're not modelling an immutable type (i.e. if the attributes foo and bar may change value within the lifetime of your obje...
Extracting text from HTML file using Python
...'d like to extract the text from an HTML file using Python. I want essentially the same output I would get if I copied the text from a browser and pasted it into notepad.
...
Getting distance between two points based on latitude/longitude
...just on answering the specific bug OP ran into.
It's because in Python, all the trig functions use radians, not degrees.
You can either convert the numbers manually to radians, or use the radians function from the math module:
from math import sin, cos, sqrt, atan2, radians
# approximate radiu...
namedtuple and default values for optional keyword arguments
...lds)
>>> Node()
Node(val=None, left=None, right=None)
Order
In all versions of Python, if you set fewer default values than exist in the namedtuple, the defaults are applied to the rightmost parameters. This allows you to keep some arguments as required arguments.
>>> Node.__ne...
What does “mro()” do?
...very attribute you get on a class's instance, not just methods, is conceptually looked up along the __mro__, so, if more than one class among the ancestors defines that name, this tells you where the attribute will be found -- in the first class in the __mro__ that defines that name.
...
How to implement a rule engine?
...Rules = rules.Select(r => CompileRule(r)).ToList();
public bool MatchesAllRules(User user)
{
return compiledRules.All(rule => rule(user));
}
Here is the implementation of BuildExpr:
Expression BuildExpr(Rule r, ParameterExpression param)
{
var left = MemberExpression.Property(param, ...
How do you get a list of the names of all files present in a directory in Node.js?
I'm trying to get a list of the names of all the files present in a directory using Node.js. I want output that is an array of filenames. How can I do this?
...
Is there a range class in C++11 for use with range based for loops?
...:irange, which is a bit more focused in scope.
C++20's range library will allow you to do this via view::iota(start, end).
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Separation of business logic and data access in django
...de is confusing and, after a certain time, I cease to understand what is really happening.
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