A tool to generate stub implementation of an interface.
The output is printed to stdout, errors (if any) — to stderr. ##Installation
go get github.com/sasha-s/goimpl/cmd/goimplgoimpl io.ReadWriteCloser "*pkg.impl"Would print
package pkg
type impl struct{}
func (i *impl) Close() (err error) {
return
}
func (i *impl) Read(u []uint8) (i1 int, err error) {
return
}
func (i *impl) Write(u []uint8) (i1 int, err error) {
return
}Let's say you already have this (the Writer is almost http.ResponseWriter, but not quite):
package w12
import "net/http"
type Writer struct{}
func (w Writer) Write(float64) (error, *int) {
return nil, nil
}
func (Writer) Header() http.Header {
return nil
}Running
goimpl -existing http.ResponseWriter "w12.Writer"Gives
package w12
type Writer struct{}
// inputs[0]: had `float64` want `[]uint8`; outputs[0]: had `error` want `int`; outputs[1]: had `*int` want `error`
func (w Writer) Write(u []uint8) (i int, err error) {
return
}
func (w Writer) WriteHeader(i int) {
return
}Here only the missing methods and the methods with wrong signature are generates.
Usage: goimpl [flags] [import1] [import2...] package.interfaceTypeName [(*|&)][package2.]typeName
This would generate empty implementation of the interfaceTypeName.
-existing=false: Would trigger generation of missing method for the existing type(struct). Note, that if you want to use a pointer receiver prefix the type with '&'.
-goimports=true: Run goimports on the generated code. The generated code might not compile if this is not set.
-named=true: Generate named return values. The genrated code might not compile if this is not set.
- impl is parsing AST, goimpl is using reflection.
- impl is much faster and has better error reporting.
- goimpl generates complete code that (usually) compiles (package/ imports).
- goimpl can generate a minimum update for the exising implementation.
- goimpl can work with ambiguous package names.