Questions tagged [trait]
The trait tag has no usage guidance.
19
questions
1
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1
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259
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Languages with PHP-like traits?
PHP have what it calls "traits" which despite the name is not like traits in Rust, Scala or other languages.
In many other languages with support for traits, a trait create a is-a relation. ...
- 479
1
vote
1
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166
views
C++20, specialize struct once per type and allow member functions to take type as reference, raw, std::unique|shared_ptr or any other smart ptr
Situation
I have some existing functions which expect containers which can be iterated and which have certain value_type. The value_type can be a value or some (smart) pointer.
All the value_type have ...
- 113
1
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1
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208
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Signature for a Rust method that modifies object but might also drop it?
I'w writing a program in Rust that basically pushes data through a pipeline of steps that transforms it in different ways. The data is represented by an Entry, and I am designing a Step trait for the ...
- 1,351
6
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3
answers
492
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How to track C++ class traits?
As a fan of regular types and value semantics, I'm keen on classes becoming more regular and being non-polymorphic. As a fan of non-throwing operations, I'm keen on operations being noexcept. I also ...
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18
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2
answers
16k
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Should a trait refer to parent methods?
Is it a code smell if the methods in my trait refer to parent::methods or to methods that are assumed to be in the utilising class?
A random (senseless) example
trait foo
{
public function bar()
...
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10
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2
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4k
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What's the difference between a Mixin and a Trait?
From what I can tell from Scala and Hack-
Mixins:
Can have state (ie. instance properties)
Can only provide concrete methods
Can have constructors, that are called in the same order that their ...
- 253
3
votes
2
answers
788
views
Using PHP traits to simulate multiple inheritance
For this question I want to present my current design and my idea of using a trait. I would like to know whether my understanding of traits is correct and whether my problem can be solved with another ...
7
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1
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643
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Comparision of modeling with inheritance vs idiomatic trait based composition
I recently I started learning Rust and Scala and what struck me was the lack of inheritance model that I'm used to in C++ and Java.
Although I can model simple things with structs and traits in Rust,...
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5
votes
2
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670
views
Does such a design pattern exist? (Multi-Strategy/Multi-Traits)
Is there a design pattern that would allow a class from a hierarchy to 'subscribe to' concrete methods?
For example, say you have an abstract base class that requires the implementation of a method.
...
- 2,343
8
votes
2
answers
7k
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Is it possible to mock and inject traits in PHPUnit?
I need to extend a third party class I cannot modify. The class's dependencies are for the most part injected through the constructor, making them easy to mock. However the class also uses methods ...
- 217
6
votes
1
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530
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What is the most generic way to provide a variable amount of outputs from a Rust function?
I am currently writing an API for machine learning algorithms in Rust and I would like for a single genetic algorithm, artificial neural network, or Bayesian network to provide multiple outputs so ...
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19
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1
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3k
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Why not make a language with mixin-only inheritance? [duplicate]
It seems that in all class-based or prototypal OOP languages, mixins are either an afterthought or a secondary feature. However, to me it looks like traditional inheritance is just a specific case of ...
- 4,827
7
votes
2
answers
2k
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Is trait composition an good practice?
So, I am now dealing with this relatively new codebase which uses, and sometimes feels like it abuses traits. Since I have been exposed to trait usage in a rather limited fashion, I was wondering ...
- 73
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0
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495
views
When to use trait components, objects, package objects in Scala
When I am adding dependencies in Scala, I tend to use mixin trait components for those that are inherit to the class itself. For example, DaoGenerator extends Generator
However, for trait components ...
- 185
6
votes
1
answer
531
views
Use StringLike instead of String in Scala?
Scala has the StringLike trait. Let's say I want to create a case class Name and internally it should save the name with some characters. Should I use case class Name(name: StringLike) or case class ...
- 2,429
11
votes
2
answers
6k
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Is there a way to document required properties in traits (PHP)?
I'm fairly new to using traits in PHP and am wondering if there is a way to ensure that a class including a trait has particular properties.
I know that you can use something like the following to ...
- 299
3
votes
2
answers
672
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How to use scala case classes when delegation is needed
Let's assume in our application we want to model cars. We also want to model a car repository where we store some registered cars. How should that be modeled in scala?
Here comes my approach: First, ...
- 2,429
10
votes
2
answers
3k
views
Why can't the Scala compiler give pattern matching warning for nonsealed classes/traits?
If I use an unsealed trait or abstract class in Scala and then use pattern matching, I wonder, does the compiler not know at compile time for this particular patternmatch what possible implementations ...
- 2,429
7
votes
1
answer
811
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Why are Scala's Either and Option types not interfaces/traits but classes?
I wanted to create a class CompileResult, that can be treated like an Either type but has some additional useful methods. It should be a CompileSuccess or a CompileFailure (which, too, has some ...
- 2,429