Instance methods, static methods, class methods: Difference between revisions
Jump to navigation
Jump to search
m (Helpful moved page Instance method, static method, class method to Instance methods, static methods, class methods) |
mNo edit summary |
||
| (2 intermediate revisions by the same user not shown) | |||
| Line 1: | Line 1: | ||
{{#addbodyclass:tag_tech}} | |||
{{#addbodyclass:tag_prog}} | |||
{{stub}} | |||
(In most languages, the way you will define all of these is considered part of a class) | |||
==Instance method== | |||
<!-- | <!-- | ||
For context, | For context, many functions defined on a class will be considered '''instance methods''': | ||
'''instance methods''': | defined on a class, will later work on an instance of that same class handed to them. | ||
you can call them on an instance | |||
they will implicitly ''always'' be working on a, | |||
In some languages, the fact that you always hand an instance into an instance method is expected to be explicitly written out, e.g. in python: | |||
<syntaxhighlight lang=""> | |||
class Foo: | |||
# (ignoring the constructor and how 'name' comes to be) | |||
def bar(self, name): | |||
self.name = name | |||
Foo.bar('quu') | |||
</syntaxhighlight> | |||
Other languages consider this so obvious that the syntax doesn't make your write that, e.g. in Java | |||
<syntaxhighlight lang=""> | |||
class Foo { | |||
# (ignoring the constructor and how 'name' comes to be) | |||
public void bar(String name) { this.name = name; } | |||
} | |||
Foo.bar("quu") | |||
</syntaxhighlight> | |||
That is not the only thing you ever want to do with a function. | That is not the only thing you ever want to do with a function. | ||
--> | |||
==Static method== | |||
<!-- | |||
you can call them on a class | |||
they don't necessarily working on an instance of that class, | |||
Another is '''static methods''': | Another is '''static methods''': | ||
: a function stuck on a class, but do ''not'' take an instance | : a function stuck on a class, but do ''not'' implicitly/inescapable take an instance | ||
: nor can they access the class definition directly | : nor can they access the class definition directly | ||
: these are often to stick some utility functions on an class rather, than just ''near'' it in a module - | : these are often to stick some utility functions on an class rather, than just ''near'' it in a module - | ||
| Line 23: | Line 57: | ||
* [[class methods]] are defined on a class, and do not take an instance, but ''do'' get a reference to that class, meaning they can fetch class variables (note: not instance variables) | For example | ||
* MyString.length( mystring_instance ) | |||
: actually a bad example, in that assuming it only works on that instance anyway, you might as well make it an instance method so you can do mystring_instance.length() - there often isn't a strong reason to do it either way. | |||
* MyString.from_regular_string( string_instance ) | |||
--> | |||
==Class method== | |||
<!-- | |||
[[class methods]] are defined on a class, and do not take an instance, but ''do'' get a reference to that class, meaning they can fetch class variables (note: not instance variables) | |||
: ...and could potentially alter that class | |||
: ...but probably more usually used for things like [[factories]]?{{verify}} | |||
: from the context of instqance variables, self.__class__ often lets you cheat you way out of needing these (but it's not as clean) | |||
: Not used much unless you do some meta-modelling, or need a reference to the class but not an instance. | |||
--> | --> | ||
Latest revision as of 14:25, 23 April 2024
✎ This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.
(In most languages, the way you will define all of these is considered part of a class)