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0
votes
1answer
77 views

Mutability, and pass-by-reference, “new” object, what am I having left out?

I started questioning what I know, or thought that I know, after this question: Array.fill differs from literal 2D definition on assignment A JavaScript question, defining an array with predefined ...
5
votes
2answers
185 views

Is it an antipattern to use peek() to modify a stream element?

Suppose I have a stream of Things and I want to "enrich" them mid stream, I can use peek() to do this, eg: streamOfThings.peek(this::thingMutator).forEach(this::someConsumer); Assume that mutating ...
2
votes
2answers
117 views

Why does an immutable object in Scala need less memory than a mutable one?

In Programming in Scala, there is this statement: For instance an empty mutable map in its default representation of HashMap takes up about 80 bytes and about 16 more are added for each entry ...
1
vote
2answers
112 views

Is it considered good practice to use mutables this way? [closed]

Lately I came across a way of using mutables which I had not thought of before. Let's say you have a list comprehension which calls a method, and you put the result in a list like the following ...
3
votes
1answer
117 views

Encapsulating mutable objects with special structure in Python

I am writing a library for working with special types of trees, called Foo trees. A Foo tree has very special structure. There some operations, called bar and baz, which only make sense on Foo trees. ...
1
vote
3answers
314 views

Addition or deletion of elements of a dynamic array

Is there any consensus among programmers (or a common convention) on the "right way" to deal with the addition or deletion of one or more elements of a dynamic (mutable) array at runtime while ...
3
votes
4answers
270 views

How to refactor my project to have less mutable objects? [duplicate]

There seems to be a trend towards immutable objects, and functional programming. I recently got aware about the benefits of immutability. However, I am not very familiar with this style of ...
50
votes
8answers
4k views

Is immutability very worthwhile when there is no concurrency?

It seems that thread-safety is always/often mentioned as the main benefit of using immutable types and especially collections. I have a situation where I would like to make sure that a method will ...
0
votes
1answer
95 views

Is it a bad idea to use mutable for pre-allocated temporaries?

Let us assume I have the following C++ class: class MyFastMessageEncoder { public: MyFastMessageEncoder() : m_fieldEncoder(ENCODING_STYLE_DEFAULT) { } void ...
5
votes
2answers
896 views

Overriding GetHashCode in a mutable struct - What NOT to do?

I am using the XNA Framework to make a learning project. It has a Point struct which exposes an X and Y value; for the purpose of optimization, it breaks the rules for proper struct design, since its ...
2
votes
2answers
209 views

Why must essential mutable derived data have an inverse function?

I was reading the paper Out of the Tar Pit authored by Ben Moseley and Peter Marks when I came across the following section on page 25 regarding essential mutable derived data: Essential Derived ...
0
votes
2answers
76 views

Mutable cursor in readonly object?

I've been searching for the different uses of the keyword mutable. I've found that it is generally used for caching, lazy computing, mutex, ... But I'm wondering if it is coherent to use it for a ...
3
votes
2answers
220 views

subclass of immutable object not immutable, can this work?

So I'm finishing up refactoring some code to remove a number of previously-mutable objects and add a better generic processing for all the classes in the domain. Just as I thought I was finishing I ...
-1
votes
4answers
1k views

Immutable vs mutable object as returned parameter for class method [closed]

There is a class method (static method) in which I create and build some object. And for filling that object, I create it as mutable object. My mutable object is a subclass of immutable object. So ...
5
votes
4answers
7k views

Is using “out” or “ref” parameters in Java methods to return extra values bad?

I happened to create a mutable class like this: class Mutable<T> { private T value; public Mutable() { this.value = null; } public Mutable(T value) { this.value = value; } T ...