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How to check if a variable is a dictionary in Python?
...t, defaultdict, or Counter from the collections module:
if isinstance(any_object, dict):
But there are even more flexible options.
Supporting abstractions:
from collections.abc import Mapping
if isinstance(any_object, Mapping):
This allows the user of your code to use their own custom implem...
What is this weird colon-member (“ : ”) syntax in the constructor?
...tion about it in any good C++ book.
You should, in most cases, initialize all member objects in the member initialization list (however, do note the exceptions listed at the end of the FAQ entry).
The takeaway point from the FAQ entry is that,
All other things being equal, your code will run...
Match whitespace but not newlines
...ghteen horizontal ones which match \h. \s matches twenty-three characters
All whitespace characters are either vertical or horizontal with no overlap, but they are not proper subsets because \h also matches U+00A0 NO-BREAK SPACE, and \v also matches U+0085 NEXT LINE, neither of which are matched by...
Cost of len() function
...
Calling len() on those data types is O(1) in CPython, the most common implementation of the Python language. Here's a link to a table that provides the algorithmic complexity of many different functions in CPython:
TimeComple...
How do I create an immutable Class?
I am working on creating an immutable class.
I have marked all the properties as read-only.
6 Answers
...
How to convert Java String into byte[]?
...m you appear to be wrestling with is that this doesn't display very well. Calling toString() will just give you the default Object.toString() which is the class name + memory address. In your result [B@38ee9f13, the [B means byte[] and 38ee9f13 is the memory address, separated by an @.
For display ...
What are some uses of decltype(auto)?
...code
For non-generic code, like the initial example you gave, you can manually select to get a reference as a return type:
auto const& Example(int const& i)
{
return i;
}
but in generic code you want to be able to perfectly forward a return type without knowing whether you are dea...
What's the difference between size_t and int in C++?
...ndly Wikipedia:
The stdlib.h and stddef.h header files define a datatype called size_t which is used to represent the size of an object. Library functions that take sizes expect them to be of type size_t, and the sizeof operator evaluates to size_t.
The actual type of size_t is platform-dependent; ...
OnCreateOptionsMenu() not called in Fragment
I have an app which got one activity with 2 fragments placed horizontally.
8 Answers
8...
Django: “projects” vs “apps”
...views.py
and so on. Would it help if I said views.py doesn't have to be called views.py? Provided you can name, on the python path, a function (usually package.package.views.function_name) it will get handled. Simple as that. All this "project"/"app" stuff is just python packages.
Now, how are yo...