What does this golang code do?

Question

I was reading DigitalOcean's golang client. I noticed that they create an instance of their *Op struct in a _ variable. Example: https://github.com/digitalocean/godo/blob/master/droplets.go#L32

var _ DropletsService = &DropletsServiceOp{}

Why is this line needed?

@CodingPickle answered this question just before I did, so if you're going to accept an answer, take his/hers. — Amit Kumar Gupta, Jan 01 '16 at 23:01

score 10 · Accepted Answer · answered Jan 01 '16 at 22:56

10

This line is a compile time check that *DropletsServiceOp satisfies the DropletsService interface.

The line has no effect on the execution of the program.

answered Jan 01 '16 at 22:56

Charlie Tumahai

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Thanks for the reply. This is a neat trick. – codefx Jan 01 '16 at 23:01

score 3 · Answer 2 · answered Jan 01 '16 at 22:57

If you look at the blame on that file, at that line, you get a clue:

https://github.com/digitalocean/godo/blame/master/droplets.go#L32

It does a compile-time check that *DropletsServiceOp satisfies the DropletsService interface. Prior to the commit introducing that, they were doing this in their test suite.

What does this golang code do?

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