What is err.(*os.PathError) in Go?

Question

When I was reading: http://golang.org/doc/effective_go.html#errors

I found such line: err.(*os.PathError) in this context:

for try := 0;         


        

Answer 1

From the docs, that is a type assertion:

For an expression x of interface type and a type T, the primary expression

 x.(T)

asserts that x is not nil and that the value stored in x is of type T. The notation x.(T) is called a type assertion.