Interfaces are an interesting concept to learn in GOLANG. There are a tonne of informative articles and here is my contribution to it.<\/p>\n\n\n\n
In classical Object Oriented everything is treated in parlance of Object<\/code> or Class<\/code> like in Java<\/code> or C++<\/code>. In Go there is no class or inheritance. <\/p>\n\n\n\n
Learn by doing<\/h2>\n\n\n\n
I started of by defining an interface <\/p>\n\n\n\n
type MyInterface interface {\n\tSet(int)\n\tGet() int\n}<\/code><\/pre>\n\n\n\n
Which exposes two methods Get<\/code> and Set<\/code> and any user defined object that implements it (as shown below) can be assigned.<\/p>\n\n\n\n
What it represents?<\/h2>\n\n\n\n
Let’s try and print the value and type for a var of type MyInterface<\/code><\/p>\n\n\n\n
%#v\ta Go-syntax representation of the value\n%T\ta Go-syntax representation of the type of the value\n<\/code><\/pre>\n\n\n\n
var myIntf MyInterface\nfmt.Printf(\" Before assigning the object %T %#v\\n\", myIntf, myIntf)<\/code><\/pre>\n\n\n\n
The output might surprise you – for those coming from the Java background.<\/p>\n\n\n\n
Before assigning the object <nil> <nil><\/code><\/pre>\n\n\n\n
The var myIntf<\/code> is essentially a pointer with a value of nil<\/code>.<\/p>\n\n\n\n
There is no explicit implements<\/code> like verb in go<\/code><\/li>
The interface can be implemented by any number of types<\/code><\/li>
Multiple interfaces can be implemented by the same type<\/code><\/li><\/ul>\n\n\n\n
Full Program<\/h2>\n\n\n\n
package main\n\nimport \"fmt\"\n\n\/\/ MyInterface defines simple set and get\ntype MyInterface interface {\n\tSet(int)\n\tGet() int\n}\n\n\/\/ Simple Struct that has only a single Value\ntype Simple struct {\n\tu int\n}\n\n\/\/ Set the value for Simple struct\nfunc (p *Simple) Set(u int) {\n\tp.u = u\n}\n\n\/\/Get returns the value in struct\nfunc (p Simple) Get() int {\n\treturn p.u\n}\n\nfunc main() {\n\tsimple := &Simple{u: 20}\n\tsimple2 := Simple{u: 21}\n\n\tfmt.Printf(\" Value: %T %#v\\n\", simple, simple)\n\tfmt.Printf(\" Value: %d\\n\", simple.Get())\n\n\tvar myIntf MyInterface\n\tfmt.Printf(\" Before assigning the object %T %#v\\n\", myIntf, myIntf)\n\n\tmyIntf = simple\n\tmyIntf.Set(22)\n\tfmt.Printf(\" Value: %T %#v\\n\", myIntf, myIntf)\n\tfmt.Printf(\" Value: %d\\n\", myIntf.Get())\n\n\tmyIntf = &simple2\n\tmyIntf.Set(24)\n\tfmt.Printf(\" Value: %T %#v\\n\", myIntf, myIntf)\n\tfmt.Printf(\" Value: %d\\n\", myIntf.Get())\n}\n<\/code><\/pre>\n\n\n\n
Output<\/h2>\n\n\n\n
API server listening at: 127.0.0.1:19141\n Value: *main.Simple &main.Simple{u:20}\n Value: 20\n Before assigning the object <nil> <nil>\n Value: *main.Simple &main.Simple{u:22}\n Value: 22\n Value: *main.Simple &main.Simple{u:24}\n Value: 24<\/code><\/pre>\n\n\n\n
Multiple Interfaces<\/h2>\n\n\n\n
How about adding another interface<\/p>\n\n\n\n
\/\/Print can do anything\ntype Print interface {\n\tPrint()\n}<\/code><\/pre>\n\n\n\n
Interfaces are an interesting concept to learn in GOLANG. There are a tonne of informative articles and here is my contribution to it. In classical Object Oriented everything is treated in parlance of Object or Class like in Java or C++. In Go there is no class or inheritance. Learn by doing I started of […]<\/p>\n","protected":false},"author":2,"featured_media":1236,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"image","meta":{"_exactmetrics_skip_tracking":false,"_exactmetrics_sitenote_active":false,"_exactmetrics_sitenote_note":"","_exactmetrics_sitenote_category":0,"footnotes":""},"categories":[137,34],"tags":[23,138],"class_list":["post-1234","post","type-post","status-publish","format-image","has-post-thumbnail","hentry","category-golang","category-technical","tag-golang","tag-interfaces","post_format-post-format-image"],"_links":{"self":[{"href":"https:\/\/blog.samarthya.me\/wps\/wp-json\/wp\/v2\/posts\/1234","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.samarthya.me\/wps\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.samarthya.me\/wps\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.samarthya.me\/wps\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.samarthya.me\/wps\/wp-json\/wp\/v2\/comments?post=1234"}],"version-history":[{"count":0,"href":"https:\/\/blog.samarthya.me\/wps\/wp-json\/wp\/v2\/posts\/1234\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blog.samarthya.me\/wps\/wp-json\/wp\/v2\/media\/1236"}],"wp:attachment":[{"href":"https:\/\/blog.samarthya.me\/wps\/wp-json\/wp\/v2\/media?parent=1234"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.samarthya.me\/wps\/wp-json\/wp\/v2\/categories?post=1234"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.samarthya.me\/wps\/wp-json\/wp\/v2\/tags?post=1234"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
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