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Why is Scala's immutable Set not covariant in its type?
...ameter of type A due to the contravariance of functions. Set could potentially be contravariant in A, but this too causes issues when you want to do things like this:
def elements: Iterable[A]
In short, the best solution is to keep things invariant, even for the immutable data structure. You'll...
How can I check if a var is a string in JavaScript?
...
Guys, I really would give an accepted answer to both of you, but I can't, all I can do is +1 to both, than give the accepted answer at who is more near to my specific problem, that I've not fully explained.
– vitt...
How to check that an object is empty in PHP?
...
empty doesn't actually check if an array is empty, empty($var) equivalent to (!isset($var) || !$var). You can replace your empty($arr)s with !$arr since array() == FALSE
– Timothy Zorn
Aug 20 '15 at 18:35...
Python argparse: default value or specified value
...
import argparse
parser = argparse.ArgumentParser()
parser.add_argument('--example', nargs='?', const=1, type=int)
args = parser.parse_args()
print(args)
% test.py
Namespace(example=None)
% test.py --example
Namespace(example=1)
% test.py --example 2
Namespace(example=2)
nargs...
LINQ: Distinct values
...
Oh so by "larger type" you may mean I still want all properties in the result even though I only want to compare a few properties to determine distinctness?
– The Red Pea
Sep 20 '16 at 14:31
...
How to restore to a different database in sql server?
...mpCopy with the contents of your.bak.
Example (restores a backup of a db called 'creditline' to 'MyTempCopy';
RESTORE FILELISTONLY FROM DISK='e:\mssql\backup\creditline.bak'
>LogicalName
>--------------
>CreditLine
>CreditLine_log
RESTORE DATABASE MyTempCopy FROM DISK='e:\mssql\backu...
Completion handler for UINavigationController “pushViewController:animated”?
...rface UINavigationController (CompletionHandler)
- (void)completionhandler_pushViewController:(UIViewController *)viewController
animated:(BOOL)animated
completion:(void (^)(void))completion;
@end
Implementation:
#import "UIN...
Global access to Rake DSL methods is deprecated
...
You can "delete" Rake 0.9.1 by running the following command:
gem uninstall rake -v=0.9.1
If you have multiple versions of the gem installed, you'll be prompted to pick a version.
After 0.9.1 was cleaned out, I ran
bundle update rake
and was finally able to create my database files. I was ...
What's the difference between %s and %d in Python string formatting?
...
what do you call these %s, %d, etc?
– Chaine
May 19 '17 at 18:21
1
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Why do we need message brokers like RabbitMQ over a database like PostgreSQL?
...ustering options are also available.
In regards to AMQP, I would say a really cool feature is the "exchange", and the ability for it to route to other exchanges. This gives you more flexibility and enables you to create a wide array of elaborate routing typologies which can come in very handy when...