Lua

colon vs. dot

A call v:name(args) is syntactic sugar for v.name(v,args), except that v is evaluated only once.

Lua manual : Function Calls
Tutorial: Understanding the colon vs. dot operator

별다른일 없으면 그냥 dot을 쓸 것. 자신(self)이 필요하면 직접 넘기는 식으로.