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Copy constructor for a class with unique_ptr
.../some stuff
};
struct Derived : public Base
{
//some stuff
};
struct Foo
{
std::unique_ptr<Base> ptr; //points to Derived or some other derived class
};
... and the goal is, as said, to make Foo copiable.
For this, one needs to do a deep copy of the contained pointer to ensure th...
What is a None value?
...n't write the sticker "F", there was already an F sticker on the None, and all you did was move it, from None to "fork". So when you type F = None, you're "reset[ting] it to its original, empty state", if we decided to treat None as meaning empty state.
I can see what he's getting at, but that's a...
Add new field to every document in a MongoDB collection
...field" : 1, "test" : "a" }
EDIT:
In case you want to add a new_field to all your collection, you have to use empty selector, and set multi flag to true (last param) to update all the documents
db.your_collection.update(
{},
{ $set: {"new_field": 1} },
false,
true
)
EDIT:
In the above ...
How to extract a git subdirectory and make a submodule out of it?
...
Nowadays there's a much easier way to do it than manually using git filter-branch: git subtree
Installation
NOTE git-subtree is now part of git (if you install contrib) as of 1.7.11, so you might already have it installed. You may check by executing git subtree.
To install...
Get element inside element by class and ID - JavaScript
...er than worrying about browser compatibility yourself (let someone else do all the work). If you want just a library to do that, then Sizzle will work great. In Sizzle, this would be be done like this:
Sizzle("#foo .bar")[0].innerHTML = "Goodbye world!";
jQuery has the Sizzle library built-in...
How to implement Enums in Ruby?
...Jun 20 '12 at 15:44
Andrew Marshall
87.3k1818 gold badges202202 silver badges204204 bronze badges
answered Sep 16 '08 at 19:32
...
Manually raising (throwing) an exception in Python
...
How do I manually throw/raise an exception in Python?
Use the most specific Exception constructor that semantically fits your issue.
Be specific in your message, e.g.:
raise ValueError('A very specific bad thing happened.')
Don't ...
How is null + true a string?
...t's walk through this in turn.
X is the null type here - or not a type at all, if you want to think of it that way. It's not providing any candidates. Y is bool, which doesn't provide any user-defined + operators. So the first step finds no user-defined operators.
The compiler then moves on to the...
Dynamic instantiation from string name of a class in dynamically imported module?
...
If you want this sentence from foo.bar import foo2 to be loaded dynamically, you should do this
foo = __import__("foo")
bar = getattr(foo,"bar")
foo2 = getattr(bar,"foo2")
instance = foo2()
...
Reference: mod_rewrite, URL rewriting and “pretty links” explained
...rver doesn't have to be Apache, there are many other web servers which are all just programs which run persistently and are attached to a port which respond to HTTP requests. You can write one yourself. This paragraph was intended to divorce you from any notion that URLs directly equal files, which ...