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Access nested dictionary items via a list of keys?
..., 'z': 3}, 'w': 3}}
Note that the Python PEP8 style guide prescribes snake_case names for functions. The above works equally well for lists or a mix of dictionaries and lists, so the names should really be get_by_path() and set_by_path():
from functools import reduce # forward compatibility for Py...
Regex lookahead, lookbehind and atomic groups
...pression.info for more details.
Positive lookahead:
Syntax:
(?=REGEX_1)REGEX_2
Match only if REGEX_1 matches; after matching REGEX_1, the match is discarded and searching for REGEX_2 starts at the same position.
example:
(?=[a-z0-9]{4}$)[a-z]{1,2}[0-9]{2,3}
REGEX_1 is [a-z0-9]{4}$ which...
Why do we need virtual functions in C++?
...s to more general). Visa-versa you need an explicit cast, usually a dynamic_cast. Anything else - very prone to undefined behavior so make sure you know what you're doing. To the best of my knowledge, this has not changed since before even C++98.
– Steve314
Jun...
sqlalchemy unique across multiple columns
... declares those in the table definition, or if using declarative as in the __table_args__:
# version1: table definition
mytable = Table('mytable', meta,
# ...
Column('customer_id', Integer, ForeignKey('customers.customer_id')),
Column('location_code', Unicode(10)),
UniqueConstraint...
What is a good pattern for using a Global Mutex in C#?
...e : IDisposable
{
//edit by user "jitbit" - renamed private fields to "_"
public bool _hasHandle = false;
Mutex _mutex;
private void InitMutex()
{
string appGuid = ((GuidAttribute)Assembly.GetExecutingAssembly().GetCustomAttributes(typeof(GuidAttribute), false).GetValue(...
How to open link in new tab on html?
...
Set the 'target' attribute of the link to _blank:
<a href="#" target="_blank" rel="noopener noreferrer">Link</a>
Edit: for other examples, see here: http://www.w3schools.com/tags/att_a_target.asp
(Note: I previously suggested blank instead of _blank beca...
Input from the keyboard in command line application
...or how I set it up.
Usage from swift
let prompt: Prompt = Prompt(argv0: C_ARGV[0])
while (true) {
if let line = prompt.gets() {
print("You typed \(line)")
}
}
ObjC wrapper to expose libedit
#import <histedit.h>
char* prompt(EditLine *e) {
return "> ";
}
@implemen...
Find all packages installed with easy_install/pip?
... there a way to find all Python PyPI packages that were installed with easy_install or pip? I mean, excluding everything that was/is installed with the distributions tools (in this case apt-get on Debian).
...
What is the most efficient way to store a list in the Django models?
...
See docs.djangoproject.com/en/3.0/topics/db/examples/many_to_one
– Jon Ison
Jul 2 at 9:42
...
Getting number of elements in an iterator in Python
...d work:
>>> iter = (i for i in range(50))
>>> sum(1 for _ in iter)
50
Although it does iterate through each item and count them, it is the fastest way to do so.
It also works for when the iterator has no item:
>>> sum(1 for _ in range(0))
0
Of course, it runs foreve...