Is there any advantage to using OO in a language that doesn't have classes or inheritance? Does declaring a method on a type give you something that declaring a function that takes the type as an argument doesn't?
Self, JavaScript, CLOS, Go, BETA, Clojure Protocols, Type Classes, COM and probably quite a few others.
What most mainstream developers know, is not the only way.
Never saw it outside the conference.
For example, `inner` being the opposite of super (e.g. call the subclasses implementation of this method). Some others, but I'm not sure I remember them (Augmentation?).
The question is not where the type syntactically is. The question is, if the dispatching between functions/methods happens dynamically or statically.
For example, say you're writing a CMS and want to make strings like the article title to be used in the URL (for readable URLs and SEO), displayed in HTML (eg inside heading tags) and also potentially used for string comparisons, you'd need to have a function to URL / HTML encode the string and you'd need to remember to do it each time you outputted the string. This can make it very easy to introduce vulnerabilities where you forget to HTML encode the string. With methods, you can force the developer to state which format to output the string as:
type DisplayText struct {
Value string
}
func (dt DisplayText) HTMLEscaped() string {
return html.EscapeString(dt.Value)
}
func (dt DisplayText) URLEscaped() string {
return url.QueryEscape(dt.Value)
}
var article_title DisplayText
fmt.Println(article_title.HTMLEscaped) fmt.Println(html.EscapeString(article_title)) fmt.Println(html.EscapeString(article_title))Like Self or javascript?
Yes. Really, interfaces are all you need for OO; class are just types-that-also-define-interfaces, and inheritance is just a shortcut for interface implementation.
While I think Go's implicit interface implementation is pretty much 180-degrees off the best way to do OO w/o classes and inheritance (I'd prefer explicit interface implementation, which eliminates interface collision), I do think clasess and inheritance get in the way more than they help.