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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 the maximum recursion depth in Python, and how to increase it?
...mple context manager like this:
import sys
class recursionlimit:
def __init__(self, limit):
self.limit = limit
self.old_limit = sys.getrecursionlimit()
def __enter__(self):
sys.setrecursionlimit(self.limit)
def __exit__(self, type, value, tb):
sys.setr...
What does `:_*` (colon underscore star) do in Scala?
...to the method with repeated parameters (as denoted with Node* above).
The _* type annotation is covered in "4.6.2 Repeated Parameters" of the SLS.
The last value parameter of a parameter section may be suffixed by “*”, e.g. (..., x:T *). The type of such a repeated parameter inside th...
c#: getter/setter
...ate the equivalent of the following simple implementation:
private string _type;
public string Type
{
get { return _type; }
set { _type = value; }
}
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Create a “with” block on several context managers? [duplicate]
...nd 3.1 and above, you can write:
with A() as X, B() as Y, C() as Z:
do_something()
This is normally the best method to use, but if you have an unknown-length list of context managers you'll need one of the below methods.
In Python 3.3, you can enter an unknown-length list of context manage...
Find out how much memory is being used by an object in Python [duplicate]
...
Try this:
sys.getsizeof(object)
getsizeof() calls the object’s __sizeof__ method and adds an additional garbage collector overhead if the object is managed by the garbage collector.
A recursive recipe
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Backup/Restore a dockerized PostgreSQL database
...
Backup your databases
docker exec -t your-db-container pg_dumpall -c -U postgres > dump_`date +%d-%m-%Y"_"%H_%M_%S`.sql
Restore your databases
cat your_dump.sql | docker exec -i your-db-container psql -U postgres
...
How do I partially update an object in MongoDB so the new object will overlay / merge with the exist
...e data then?
You know you can do the following:
db.collection.update( { _id:...} , { $set: someObjectWithNewData }
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How to copy a row and insert in same table with a autoincrement field in MySQL?
...
Use INSERT ... SELECT:
insert into your_table (c1, c2, ...)
select c1, c2, ...
from your_table
where id = 1
where c1, c2, ... are all the columns except id. If you want to explicitly insert with an id of 2 then include that in your INSERT column list and your SE...
In Scala, what exactly does 'val a: A = _' (underscore) mean?
What exactly does val a: A = _ initialize a value to? Is this a typed null? Thanks.
2 Answers
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