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Is null reference possible?
...
References are not pointers.
8.3.2/1:
A reference shall be initialized to
refer to a valid object or function.
[Note: in particular, a null reference
cannot exist in a well-defined
program, because the only way to
create such a reference would be to
bind it to the ...
Rails params explained?
...e "1" and params[:boo] would be "octopus".
In HTTP/HTML, the params are really just a series of key-value pairs where the key and the value are strings, but Ruby on Rails has a special syntax for making the params be a hash with hashes inside. For example, if the user's browser requested
http://w...
Is it considered bad practice to perform HTTP POST without entity body?
...example below) doesn't have a parameter to accept a body.
the method "post_disable_db" just accepts a path parameter "db_name" and doesn't have a 2nd parameter which would imply a mandatory body.
@router.post('/{db_name}/disable',
status_code=HTTP_200_OK,
response_model=R...
Is it bad practice to have a constructor function return a Promise?
...create and initialize a new instance. It should set up data structures and all instance-specific properties, but not execute any tasks. It should be a pure function without side effects if possible, with all the benefits that has.
What if I want to execute things from my constructor?
That shou...
How do I reference an existing branch from an issue in GitHub?
...ant to do this, I manually make the link like this:
[a link to a branch](/_user_/_project_/tree/_branch_)
Where _user_, _project_, and _branch_ should be replaced with the parts of the branch's URL. For example, a branch in GitHub's "linguist" project:
[api-changes branch in github/linguist](/g...
Scala: Nil vs List()
In Scala, is there any difference at all between Nil and List() ?
3 Answers
3
...
Match multiple cases classes in scala
... matcher(l: Foo): String = {
l match {
case A() => "A"
case B(_) | C(_) => "B"
case _ => "default"
}
}
If you must, must, must extract the parameter and treat them in the same code block, you could:
def matcher(l: Foo): String = {
l match {
case A() => "A"
ca...
Instance variables vs. class variables in Python
...r instance. If there would be more than one instance (which won't happen), all instance should have the same configuration. I wonder which of the following options would be better or more "idiomatic" Python.
...
how to create a file name with the current date & time in python?
... human readable.
from datetime import datetime
datetime.now().strftime("%Y_%m_%d-%I_%M_%S_%p")
'2020_08_12-03_29_22_AM'
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Simulate CREATE DATABASE IF NOT EXISTS for PostgreSQL?
...an work around it from within psql by executing the DDL statement conditionally:
SELECT 'CREATE DATABASE mydb'
WHERE NOT EXISTS (SELECT FROM pg_database WHERE datname = 'mydb')\gexec
The manual:
\gexec
Sends the current query buffer to the server, then treats each column of each row of the query's...