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0 pointsNateDad12y ago0 comments

So you're saying you'd prefer it if you had to explicitly tell Go that your type implements an interface? Something like this?

  type Shape interface {
      Area() int
  }

  type Square struct {
     sideLen int
  }

  // Somehow denote that this function is implementing
  // Shape's Area function
  func (s Square) Shape.Area() int {
      return sideLen * sideLen
  }

Because, one of the things I like best about Go's interfaces is that you don't have to do that.

type Shape interface { Area() int } type Square struct { sideLen int } // Somehow denote that this function is implementing // Shape's Area function func (s Square) Shape.Area() int { return sideLen * sideLen }

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4 comments · 1 top-level

dragonwriter12y ago· 3 in thread

> So you're saying you'd prefer it if you had to explicitly tell Go that your type implements an interface?

I'd prefer that to having to avoid using the most natural names for methods to avoid implementing an unintended interface -- it seems to me that Go's approach in this area makes easy things easier and hard things harder.

NateDadOP12y ago

Why do you care if you accidentally implement an interface?

dragonwriter12y ago

Because conforming to the signatures necessary to implement an interface doesn't imply confirming to its semantics, so accidental interface "implementations" are a type-safety problem.

NateDadOP12y ago

They're really not. You still have to have someone pass your type into something expecting an interface. It's no different than passing a string into something expecting a path when you pass it an html document... at some point the programmer needs to decide if passing the value into the method makes sense.

In the canonical example:

  type Boat interface {
      Launch()  
  }

  func LaunchBoat(b Boat) {
     // do some boat stuff

     b.Launch()
  }

  type NuclearMissile struct{}

  func (nm NuclearMissile) Launch() {
      // launch nuclear missile
  }

  func main() {
      rocket := NuclearMissile{}
      LaunchBoat(rocket)
  }

Sure, this compiles, but the code doesn't make any sense. Lots of things compile, that doesn't mean the code makes sense. At some point it's the programmer's responsibility to think a little.

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