A mutable can be modified after it is created.
A mutable can be modified after it is created. It is a keyword in functional programming opposite to immutable.
Related tags:
Questions tagged [mutable]
1184 questions
92
votes
7 answers
Immutable/Mutable Collections in Swift
I was referring to Apple's Swift programming guide for understanding creation of Mutable/ immutable objects(Array, Dictionary, Sets, Data) in Swift language. But I could't understand how to create a immutable collections in Swift.
I would like to…
Pranav Jaiswal
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89
votes
7 answers
What is the syntax for adding an element to a scala.collection.mutable.Map?
What is the syntax for adding an element to a scala.collection.mutable.Map ?
Here are some failed attempts:
val map = scala.collection.mutable.Map
map("mykey") = "myval"
map += "mykey" -> "myval"
map.put("mykey","myval")
Koala3
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84
votes
2 answers
Should mutexes be mutable?
Not sure if this is a style question, or something that has a hard rule...
If I want to keep the public method interface as const as possible, but make the object thread safe, should I use mutable mutexes? In general, is this good style, or should a…
Marcin
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83
votes
4 answers
Converting mutable to immutable map
private[this]object MMMap extends HashMap[A, Set[B]] with MultiMap[A, B]
How convert it to immutable?
Jeriho
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83
votes
5 answers
Mutable variable is accessible from closure. How can I fix this?
I am using Typeahead by twitter. I am running into this warning from Intellij. This is causing the "window.location.href" for each link to be the last item in my list of items.
How can I fix my code?
Below is my code:
AutoSuggest.prototype.config =…
iCodeLikeImDrunk
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75
votes
10 answers
Are mutable hashmap keys a dangerous practice?
Is it bad practice to use mutable objects as Hashmap keys? What happens when you try to retrieve a value from a Hashmap using a key that has been modified enough to change its hashcode?
For example, given
class Key
{
int a; //mutable field
…
donnyton
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66
votes
5 answers
In Kotlin, how do you modify the contents of a list while iterating
I have a list:
val someList = listOf(1, 20, 10, 55, 30, 22, 11, 0, 99)
And I want to iterate it while modifying some of the values. I know I can do it with map but that makes a copy of the list.
val copyOfList = someList.map { if (it <= 20) it +…
Jayson Minard
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61
votes
3 answers
Which JavaScript Array functions are mutating?
I am writing an Array-derived class in JavaScript and need to know which functions to overload so that I can be aware of changes made to the array.
I know Array.push() and Array.splice() are mutating. Is there a definitive list of any others?
devios1
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60
votes
1 answer
How to append or prepend on a Scala mutable.Seq
There's something I don't understand about Scala's collection.mutable.Seq. It describes the interface for all mutable sequences, yet I don't see methods to append or prepend elements without creating a new sequence. Am I missing something obvious…
Jean-Philippe Pellet
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58
votes
10 answers
What is difference between mutable and immutable String in java
As per my knowledge,
a mutable string can be changed, and
an immutable string cannot be changed.
Here I want to change the value of String like this,
String str="Good";
str=str+" Morning";
and other way is,
StringBuffer str= new…
Raghu
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53
votes
8 answers
Mutable strings in Python
Do you know of a Python library which provides mutable strings? Google returned surprisingly few results. The only usable library I found is http://code.google.com/p/gapbuffer/ which is in C but I would prefer it to be written in pure Python.
Edit:…
Ecir Hana
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52
votes
7 answers
Is the use of del bad?
I commonly use del in my code to delete objects:
>>> array = [4, 6, 7, 'hello', 8]
>>> del(array[array.index('hello')])
>>> array
[4, 6, 7, 8]
>>>
But I have heard many people say that the use of del is unpythonic. Is using del bad practice?
>>>…
A.J. Uppal
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49
votes
7 answers
Swift - How to mutate a struct object when iterating over it
I am still not sure about the rules of struct copy or reference.
I want to mutate a struct object while iterating on it from an array:
For instance in this case I would like to change the background color
but the compiler is yelling at me
struct…
Avba
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47
votes
4 answers
Always declare std::mutex as mutable in C++11?
After watching Herb Sutter's talk You Don't Know const and mutable, I wonder whether I should always define a mutex as mutable? If yes, I guess the same holds for any synchronized container (e.g., tbb::concurrent_queue)?
Some background: In his…
Philipp Claßen
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44
votes
2 answers
Why did Matz choose to make Strings mutable by default in Ruby?
It's the reverse of this question: Why can't strings be mutable in Java and .NET?
Was this choice made in Ruby only because operations (appends and such) are efficient on mutable strings, or was there some other reason?
(If it's only efficiency,…
Seth Tisue
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