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What are all the uses of an underscore in Scala?
...: K[T])
Ignored variables
val _ = 5
Ignored parameters
List(1, 2, 3) foreach { _ => println("Hi") }
Ignored names of self types
trait MySeq { _: Seq[_] => }
Wildcard patterns
Some(5) match { case Some(_) => println("Yes") }
Wildcard patterns in interpolations
"abc" match { ca...
Best practices for circular shift (rotate) operations in C++
... are already available in C++.
However, I couldn't find out how I could perform circular shift or rotate operations.
16 Ans...
In which situations do we need to write the __autoreleasing ownership qualifier under ARC?
...declaration means __strong, implicitly:
NSError * e = nil;
Will be transformed to:
NSError * __strong error = nil;
When you call your save method:
- ( BOOL )save: ( NSError * __autoreleasing * );
The compiler will then have to create a temporary variable, set at __autoreleasing. So:
NSErro...
method of iterating over sqlalchemy model's defined columns?
... iterate over the list of columns defined in a SQLAlchemy model. I want it for writing some serialization and copy methods to a couple of models. I can't just iterate over the obj.__dict__ since it contains a lot of SA specific items.
...
Which is more preferable to use: lambda functions or nested functions ('def')?
...ign the lambda to a name, use a def instead. defs are just syntactic sugar for an assignment, so the result is the same, and they are a lot more flexible and readable.
lambdas can be used for use once, throw away functions which won't have a name.
However, this use case is very rare. You rarely ne...
Should I use a class or dictionary?
...ter want to add some code? Where would your __init__ code go?
Classes are for bundling related data (and usually code).
Dictionaries are for storing key-value relationships, where usually the keys are all of the same type, and all the values are also of one type. Occasionally they can be useful fo...
How can I get the client's IP address in ASP.NET MVC?
... MAY use the de facto standard of placing the client's IP address in the X-Forwarded-For HTTP header. Aside from there is no guarantee that a request has a X-Forwarded-For header, there is also no guarantee that the X-Forwarded-For hasn't been SPOOFED.
Original Answer
Request.UserHostAddress
T...
What's the difference between globals(), locals(), and vars()?
...: '__main__',
}
So far, everything I've said about locals() is also true for vars()... here's the difference: vars() accepts a single object as its argument, and if you give it an object it returns the __dict__ of that object. For a typical object, its __dict__ is where most of its attribute dat...
Why is Python 3.x's super() magic?
...current implementation instead. He anticipated that using a different name for super() could be a problem:
My patch uses an intermediate solution: it assumes you need __class__
whenever you use a variable named 'super'. Thus, if you (globally)
rename super to supper and use supper but not su...
How to get a function name as a string?
...unction.__name__
Using __name__ is the preferred method as it applies uniformly. Unlike func_name, it works on built-in functions as well:
>>> import time
>>> time.time.func_name
Traceback (most recent call last):
File "<stdin>", line 1, in ?
AttributeError: 'builtin_fun...