Making integers mutable would be very counter-intuitive to the way we are used to working with them. Consider this code fragment: a = 1 # assign 1 to a b = a+2 # assign 3 to b, leave a at 1 After these assignments are executed we expect a to have the value 1 and … Read more
Yeah, you can do this. Keep in mind, since you’re not attaching it to a layout, you’ll need to lay it out manually before drawing it: view.layout(0, 0, viewWidth, viewHeight); And unless you just know exactly what you want for those width and height parameters, you may also want to measure it first: int widthSpec … Read more
Mutability for sequences only guarantees that you’ll be able to swap out the items for different ones (via the update method), as you can with e.g. primitive arrays. It does not guarantee that you’ll be able to make the sequence larger (that’s what the Growable trait is for) or smaller (Shrinkable). Buffer is the abstract … Read more
Python 3 From the docs: Concatenating immutable sequences always results in a new object. This means that building up a sequence by repeated concatenation will have a quadratic runtime cost in the total sequence length. To get a linear runtime cost, you must switch to one of the alternatives below: if concatenating str objects, you … Read more
It allows the differentiation of bitwise const and logical const. Logical const is when an object doesn’t change in a way that is visible through the public interface, like your locking example. Another example would be a class that computes a value the first time it is requested, and caches the result. Since c++11 mutable … Read more
Yes, strings in Ruby, unlike in Python, are mutable. s += “hello” is not appending “hello” to s – an entirely new string object gets created. To append to a string ‘in place’, use <<, like in: s = “hello” s << ” world” s # hello world
This is in line with Ruby’s design, as you note. Immutable strings are more efficient than mutable strings – less copying, as strings are re-used – but make work harder for the programmer. It is intuitive to see strings as mutable – you can concatenate them together. To deal with this, Java silently translates concatenation … Read more
No. However, most of the time they will be. While it’s helpful to think of const as “thread-safe” and mutable as “(already) thread-safe”, const is still fundamentally tied to the notion of promising “I won’t change this value”. It always will be. I have a long-ish train of thought so bear with me. In my … Read more
struct are value types, thus in the for loop you are dealing with a copy. Just as a test you might try this: Swift 3: struct Options { var backgroundColor = UIColor.black } var arrayOfMyStruct = [Options]() for (index, _) in arrayOfMyStruct.enumerated() { arrayOfMyStruct[index].backgroundColor = UIColor.red } Swift 2: struct Options { var backgroundColor = … Read more
The other answers are looking at it from a technical point of view (i.e. what’s the best way to modify a list), but I would say the (much) more important reason people recommend, for example, slicing, is that it doesn’t modify the original list. The reason for this in turn is that usually, the list … Read more