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Defining an abstract class without any abstract methods
...
Of course.
Declaring a class abstract only means that you don't allow it to be instantiated on its own.
Declaring a method abstract means that subclasses have to provide an implementation for that method.
The two are separate concepts, though obviously you can't have an abstract method ...
What does a double * (splat) operator do
... the double splat operator which is available since Ruby 2.0.
It captures all keyword arguments (which can also be a simple hash, which was the idiomatic way to emulate keyword arguments before they became part of the Ruby language)
def my_method(**options)
puts options.inspect
end
my_method(ke...
The Ruby %r{ } expression
...
%r{} is equivalent to the /.../ notation, but allows you to have '/' in your regexp without having to escape them:
%r{/home/user}
is equivalent to:
/\/home\/user/
This is only a syntax commodity, for legibility.
Edit:
Note that you can use almost any non-alphabet...
Reconnection of Client when server reboots in WebSocket
...in amount of disconnects will cause a stack overflow. That is because you call start recursively, without ever returning.
– Forivin
Dec 3 '16 at 14:14
11
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jquery how to empty input field
...0' max="10" value="5"></input>? I guess said differently, are you allowed to set a numeric input to be blank?
– Kevin Wheeler
Jun 10 '15 at 21:49
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Convert a python UTC datetime to a local datetime using only python standard library?
...timezone on Unix and Win32
# from tzlocal import get_localzone # $ pip install tzlocal
# # get local timezone
# local_tz = get_localzone()
def utc_to_local(utc_dt):
local_dt = utc_dt.replace(tzinfo=pytz.utc).astimezone(local_tz)
return local_tz.normalize(local_dt) # .normalize might be...
AWS S3: how do I see how much disk space is using
...
Yippe - an update to AWS CLI allows you to recursively ls through buckets...
aws s3 ls s3://<bucketname> --recursive | grep -v -E "(Bucket: |Prefix: |LastWriteTime|^$|--)" | awk 'BEGIN {total=0}{total+=$3}END{print total/1024/1024" MB"}'
...
Error 1046 No database Selected, how to resolve?
...he SQL Development heading of the Workbench splash screen.
Addendum
This all assumes there's a database you want to create the table inside of - if not, you need to create the database before anything else:
CREATE DATABASE your_database;
...
SQL standard to escape column names?
...ody> <double quote>
Oracle, PostgreSQL, MySQL, MSSQL and SQlite all support " as the identifier delimiter.
They don't all use " as the 'default'. For example, you have to be running MySQL in ANSI mode and SQL Server only supports it when QUOTED_IDENTIFIER is ON.
...
How do you merge two Git repositories?
...hub.com/rails/rails.git master
This will appear as a single commit where all files of Rails master branch are added into "rails" directory.
However the commit's title contains a reference to the old history tree:
Add 'rails/' from commit <rev>
Where <rev> is a SHA-1 commit hash. ...