File1.go

Package abc

type ECA struct {
    *CA
    obcKey          []byte
    obcPriv, obcPub []byte
    gRPCServer      *grpc.Server
}


type ECAP struct {
    eca *ECA
}


func (ecap *ECAP) ReadCACertificate(ctx context.Context, in *pb.Empty) (*pb.Cert, error) {
    Trace.Println("gRPC ECAP:ReadCACertificate")

    return &pb.Cert{Cert: ecap.eca.raw}, nil
}

File2.go

package main

import "abc"

var ecap abc.ECAP //creating instance

func main() {
    err = ecap.ReadCACertificate(floo,floo)
}

I am a newbie. I want to create instance of ECAP struct and call ReadCACertificate method. Right now i am creating like this "var ecap abc.ECAP //creating instance" which is giving "nil" and nil pointer error.

Can anyone help how to call the ReadCACertificate method in efficient way.

Thanks in advance.

You need to import the second file from your $GOPATH. And your function return 2 values, not just an error.

package main


import (
     "$RELATIVE_PATH_FROM_GOPATH/abc"
)


var ecap := ECAP{new(ECA)} //initialize your struct, since it has pointers

func main() {
    cert, err = ecap.ReadCACertificate(floo,floo)
}

File 1

type ECAP struct {
    Eca *ECA //uppercase make field be exported
}

Your example is incomplete, but basically you need to initialize your struct, since it has pointers, and default pointer value is nil.

var ecap := ECAP{new(ECA)}