Python π objects have one important characteristic about them:
Some objects are mutable, which means their contents can be changed.
This β‘𧡠will explain what (im)mutability means in Python π.
Let's go π
Some objects are mutable, which means their contents can be changed.
This β‘𧡠will explain what (im)mutability means in Python π.
Let's go π
The (im)mutability of an object depends on its type.
In other words, (im)mutability is a characteristic of types, not of specific objects!
For example,
π ALL integers are immutable.
π ALL lists are mutable.
With me so far?
In other words, (im)mutability is a characteristic of types, not of specific objects!
For example,
π ALL integers are immutable.
π ALL lists are mutable.
With me so far?
But what exactly does it mean for an object to be mutable?
Or for an object to be immutable?
Recall that an object is characterised by
π its identity
π its type
π its contents.
I wrote about that in this thread π
Or for an object to be immutable?
Recall that an object is characterised by
π its identity
π its type
π its contents.
I wrote about that in this thread π
https://twitter.com/mathsppblog/status/1445148566721335298
Take a type, any type.
If you can change the contents of its objects without changing its identity and its type, that type is mutable.
Lists are a great example of a mutable data type.
Why?
If you can change the contents of its objects without changing its identity and its type, that type is mutable.
Lists are a great example of a mutable data type.
Why?
Because lists are containers: you can put things inside lists and you can remove stuff from inside those same lists.
π you can see how the contents of the list `obj` change as we make method calls...
But the identity of the list remains the same!
π you can see how the contents of the list `obj` change as we make method calls...
But the identity of the list remains the same!
However, when dealing with immutable objects, it's a completely different story.
If we check an English dictionary, this is what we get for the definition of βimmutableβ:
π adjective: immutable β unchanging over time or unable to be changed.
If we check an English dictionary, this is what we get for the definition of βimmutableβ:
π adjective: immutable β unchanging over time or unable to be changed.
Immutable objects' contents never change.
Take a string as an example.
Strings are a good example for this discussion because, sometimes, they can look mutable.
But they are not!
Here π, string indices cannot be assigned to!
Take a string as an example.
Strings are a good example for this discussion because, sometimes, they can look mutable.
But they are not!
Here π, string indices cannot be assigned to!
If you want to change the string that `s` points to...
You need to assign a completely new string to `s`!
Another thing that hints at the fact that strings are immutable are its methods.
String methods all return new strings.
None of them change the string in-place...
You need to assign a completely new string to `s`!
Another thing that hints at the fact that strings are immutable are its methods.
String methods all return new strings.
None of them change the string in-place...
Notice how `s` wasn't updated automatically to "HELLO, WORLD!".
Instead, the new string was created and returned to you.
As you can see, you can use a string to build OTHER strings!
But you can never change the original string itself.
Instead, the new string was created and returned to you.
As you can see, you can use a string to build OTHER strings!
But you can never change the original string itself.
As a reference, here are some common (im)mutable built-in types:
π MUTABLE: lists, dicts, and sets
(containers are typically mutable)
π IMMUTABLE: ints, floats, complex numbers, Booleans, strings, and tuples.
π MUTABLE: lists, dicts, and sets
(containers are typically mutable)
π IMMUTABLE: ints, floats, complex numbers, Booleans, strings, and tuples.
That's it for this β‘π§΅
Did you learn something new?
The content for this thread come from the subsection of my most recent Python π article, you can check it out here π
mathspp.com/blog/pydonts/pβ¦
Did you learn something new?
The content for this thread come from the subsection of my most recent Python π article, you can check it out here π
mathspp.com/blog/pydonts/pβ¦
Are you learning Python π?
Then, follow @mathsppblog for π₯π€― Python content!
TL;DR
π mutable objects are those whose internal contents can be changed (like lists)
π immutable objects can only be used to create new ones (list strings or ints)
See you around π
Then, follow @mathsppblog for π₯π€― Python content!
TL;DR
π mutable objects are those whose internal contents can be changed (like lists)
π immutable objects can only be used to create new ones (list strings or ints)
See you around π
Woooops, the second bullet point has a typo: "list" β "like"
π immutable objects can only be used to create new ones (like strings or ints)
Thanks @learn_byexample for noticing & letting me know.
π immutable objects can only be used to create new ones (like strings or ints)
Thanks @learn_byexample for noticing & letting me know.
β’ β’ β’
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