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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...
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 does = +_ mean in JavaScript
I was wondering what the = +_ operator means in JavaScript. It looks like it does assignments.
12 Answers
...
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...
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...
How do I list all files of a directory?
...
A bit simpler: (_, _, filenames) = walk(mypath).next() (if you are confident that the walk will return at least one value, which it should.)
– misterbee
Jul 14 '13 at 20:56
...
How do I get bash completion to work with aliases?
...
As stated in the comments above,
complete -o default -o nospace -F _git_checkout gco
will no longer work. However, there's a __git_complete function in git-completion.bash which can be used to set up completion for aliases like so:
__git_complete gco _git_checkout
...
What is time_t ultimately a typedef to?
...
The time_t Wikipedia article article sheds some light on this. The bottom line is that the type of time_t is not guaranteed in the C specification.
The time_t datatype is a data type in
the ISO C library defined for storing
s...
Where do the Python unit tests go?
...
For a file module.py, the unit test should normally be called test_module.py, following Pythonic naming conventions.
There are several commonly accepted places to put test_module.py:
In the same directory as module.py.
In ../tests/test_module.py (at the same level as the code directory)....
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
...