:: is basically a namespace resolution operator. It allows you to access items in modules, or class-level items in classes. For example, say you had this setup: module SomeModule module InnerModule class MyClass CONSTANT = 4 end end end You could access CONSTANT from outside the module as SomeModule::InnerModule::MyClass::CONSTANT. It doesn’t affect instance methods defined … Read more
Depends upon the version. The If operator in VB.NET 2008 is a ternary operator (as well as a null coalescence operator). This was just introduced, prior to 2008 this was not available. Here’s some more info: Visual Basic If announcement Example: Dim foo as String = If(bar = buz, cat, dog) [EDIT] Prior to 2008 … Read more
It’s not because it doesn’t make sense; it makes perfect sense to define “x++” as “x += 1, evaluating to the previous binding of x”. If you want to know the original reason, you’ll have to either wade through old Python mailing lists or ask somebody who was there (eg. Guido), but it’s easy enough … Read more
It’s the null conditional operator. It basically means: “Evaluate the first operand; if that’s null, stop, with a result of null. Otherwise, evaluate the second operand (as a member access of the first operand).” In your example, the point is that if a is null, then a?.PropertyOfA will evaluate to null rather than throwing an … Read more
Note: Originally I posted C# code in this answer for purposes of illustration, since C# allows you to pass int parameters by reference with the ref keyword. I’ve decided to update it with actual legal Java code using the first MutableInt class I found on Google to sort of approximate what ref does in C#. … Read more
It’s shorthand for tags.map(&:name.to_proc).join(‘ ‘) If foo is an object with a to_proc method, then you can pass it to a method as &foo, which will call foo.to_proc and use that as the method’s block. The Symbol#to_proc method was originally added by ActiveSupport but has been integrated into Ruby 1.8.7. This is its implementation: class … Read more
In Python 3.x, 5 / 2 will return 2.5 and 5 // 2 will return 2. The former is floating point division, and the latter is floor division, sometimes also called integer division. In Python 2.2 or later in the 2.x line, there is no difference for integers unless you perform a from __future__ import … Read more
I’m going to heavily quote the Object documentation here, because I think it has some great explanations. I encourage you to read it, and also the documentation for these methods as they’re overridden in other classes, like String. Side note: if you want to try these out for yourself on different objects, use something like … Read more
Take a look at this: >>> a = 256 >>> b = 256 >>> id(a) 9987148 >>> id(b) 9987148 >>> a = 257 >>> b = 257 >>> id(a) 11662816 >>> id(b) 11662828 Here’s what I found in the Python 2 documentation, “Plain Integer Objects” (It’s the same for Python 3): The current implementation keeps … Read more
It suppresses error messages — see Error Control Operators in the PHP manual.