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Why do we use __init__ in Python classes?
...ical piece of understanding: the difference between a class and an object. __init__ doesn't initialize a class, it initializes an instance of a class or an object. Each dog has colour, but dogs as a class don't. Each dog has four or fewer feet, but the class of dogs doesn't. The class is a concept o...
Naming convention - underscore in C++ and C# variables
It's common to see a _var variable name in a class field. What does the underscore mean? Is there a reference for all these special naming conventions?
...
Extracting bits with a single multiplication
...and, namely SMT-LIB 2 input:
(set-logic BV)
(declare-const mask (_ BitVec 64))
(declare-const multiplicand (_ BitVec 64))
(assert
(forall ((x (_ BitVec 64)))
(let ((y (bvmul (bvand mask x) multiplicand)))
(and
(= ((_ extract 63 63) x) ((_ extract 63 63) y))
(= ...
How to put multiple statements in one line?
...e generally discouraged.
Yes:
if foo == 'blah':
do_blah_thing()
do_one()
do_two()
do_three()
Rather not:
if foo == 'blah': do_blah_thing()
do_one(); do_two(); do_three()
Here is a sample comprehension to make the distinction:
>>...
What is a proper naming convention for MySQL FKs?
...ue name automatically.
In any case, this is the convention that I use:
fk_[referencing table name]_[referenced table name]_[referencing field name]
Example:
CREATE TABLE users(
user_id int,
name varchar(100)
);
CREATE TABLE messages(
message_id int,
user_id int
);
...
rgdal package installation
...file update
Then, when you get an error such as :
configure: error: proj_api.h not found in standard or given locations.
You can use the following command to find which package you must install to get the missing file :
$ apt-file search proj_api.h
libproj-dev: /usr/include/proj_api.h
...
What's the best UI for entering date of birth? [closed]
...birthdate.
A text box with an example is clear, quick and easy to enter:
_______
|_______| (example: 31/3/1970)
This should support flexible formatting such as 1/1/1970 or 20/07/70.
If you have to support different cultures with different date conventions (e.g. US and UK) then this could be err...
Getter and Setter declaration in .NET [duplicate]
...ed property. When the need arises you can expand your property to:
string _myProperty;
public string MyProperty
{
get { return _myProperty; }
set { _myProperty = value; }
}
Now you can add code that validates the value in your setter:
set
{
if (string.IsNullOrWhiteSpace(value))
...
Basic http file downloading and saving to disk in python?
...URLopener is deprecated.
And when used you will get error as below:
url_opener = urllib.URLopener() AttributeError: module 'urllib' has no
attribute 'URLopener'
So, try:
import urllib.request
urllib.request.urlretrieve(url, filename)
...
Can a variable number of arguments be passed to a function?
... this. The key point is that the general signature of a function is f(*list_args, **keyword_args) (not f(*list_args)).
– Eric O Lebigot
Mar 15 '13 at 3:36
...