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Why do we need virtual functions in C++?
... a rat."
So far so good, right? Animals eat generic food, cats eat rats, all without virtual.
Let's change it a little now so that eat() is called via an intermediate function (a trivial function just for this example):
// This can go at the top of the main.cpp file
void func(Animal *xyz) { xyz-...
Determine the type of an object?
...object, and isinstance() to check an object’s type against something. Usually, you want to use isistance() most of the times since it is very robust and also supports type inheritance.
To get the actual type of an object, you use the built-in type() function. Passing an object as the only param...
Why can't I use a list as a dict key in python?
..., with the hash as, say, their memory location?
It can be done without really breaking any of the requirements, but it leads to unexpected behavior. Lists are generally treated as if their value was derived from their content's values, for instance when checking (in-)equality. Many would - underst...
Getters \ setters for dummies
...
Isnt it really painful that MS does not support JS correctly and they do not make their silverlight run everywhere, so I have to program everything twice, one for SL and one for rest of the world :)
– Akash Kava
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git ignore vim temporary files
...t is the correct way to make git ignore temporary files produced by vim in all directories (either globally across the system or locally for a single project)?
...
What are rvalues, lvalues, xvalues, glvalues, and prvalues?
...e they needed? Probably not if we wish to forfeit the new features. But to allow better optimization we should probably embrace them.
Quoting n3055:
An lvalue (so-called, historically,
because lvalues could appear on the
left-hand side of an assignment
expression) designates a function or
an obj...
class
...lass << foo syntax opens up foo's singleton class (eigenclass). This allows you to specialise the behaviour of methods called on that specific object.
a = 'foo'
class << a
def inspect
'"bar"'
end
end
a.inspect # => "bar"
a = 'foo' # new object, new singleton class
a.insp...
Get model's fields in Django
Given a Django model, I'm trying to list all of its fields. I've seen some examples of doing this using the _meta model attribute, but doesn't the underscore in front of meta indicate that the _meta attribute is a private attribute and shouldn't be accessed directly? ... Because, for example, the ...
How to downgrade or install an older version of Cocoapods
How can I downgrade Cocoapods to an older version, or how can I install an older version of Cocoapods?
6 Answers
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How do I add multiple arguments to my custom template filter in a django template?
...
It is possible and fairly simple.
Django only allows one argument to your filter, but there's no reason you can't put all your arguments into a single string using a comma to separate them.
So for example, if you want a filter that checks if variable X is in the list [1...