Add generic interactor constructor (#8)

Author: vearutop

.github/workflows/tip.yml

@@ -0,0 +1,33 @@
+name: tip
+on:
+  push:
+    branches:
+      - master
+      - main
+  pull_request:
+env:
+  GO111MODULE: "on"
+  RUN_BASE_COVERAGE: "on"  # Runs test for PR base in case base test coverage is missing.
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v2
+      - name: Go cache
+        uses: actions/cache@v2
+        with:
+          # In order:
+          # * Module download cache
+          # * Build cache (Linux)
+          path: |
+            ~/go/pkg/mod
+            ~/.cache/go-build
+          key: ${{ runner.os }}-go-cache-${{ hashFiles('**/go.sum') }}
+          restore-keys: |
+            ${{ runner.os }}-go-cache
+      - name: Test
+        uses: docker://aleksi/golang-tip:master
+        with:
+          entrypoint: /bin/sh
+          args: -c "go version;make test-unit"

Makefile

@@ -23,7 +23,7 @@ ifeq ($(DEVGO_PATH),)
 	DEVGO_PATH := $(shell GO111MODULE=on $(GO) list ${modVendor} -f '{{.Dir}}' -m github.com/bool64/dev)
 	ifeq ($(DEVGO_PATH),)
     	$(info Module github.com/bool64/dev not found, downloading.)
-    	DEVGO_PATH := $(shell export GO111MODULE=on && $(GO) mod tidy && $(GO) list -f '{{.Dir}}' -m github.com/bool64/dev)
+    	DEVGO_PATH := $(shell export GO111MODULE=on && $(GO) get github.com/bool64/dev && $(GO) list -f '{{.Dir}}' -m github.com/bool64/dev)
 	endif
 endif
 

README.md

@@ -24,6 +24,8 @@ This abstraction is intended for use with automated transport layer, for example
 
 ## Usage
 
+### Input/Output Definitions
+
 ```go
 // Configure use case interactor in application layer.
 type myInput struct {
@@ -36,6 +38,10 @@ type myOutput struct {
     Value2 string `json:"value2"`
 }
 
+```
+### Classic API
+
+```go
 u := usecase.NewIOI(new(myInput), new(myOutput), func(ctx context.Context, input, output interface{}) error {
     var (
         in  = input.(*myInput)
@@ -53,6 +59,30 @@ u := usecase.NewIOI(new(myInput), new(myOutput), func(ctx context.Context, input
     return nil
 })
 
+```
+
+### Generic API with type parameters
+
+With `go1.18` and later (or [`gotip`](https://pkg.go.dev/golang.org/dl/gotip)) you can use simplified generic API instead 
+of classic API based on `interface{}`.
+
+```go
+u := usecase.NewInteractor(func(ctx context.Context, input myInput, output *myOutput) error {
+    if in.Param1%2 != 0 {
+        return status.InvalidArgument
+    }
+
+    // Do something to set output based on input.
+    out.Value1 = in.Param1 + in.Param1
+    out.Value2 = in.Param2 + in.Param2
+
+    return nil
+})
+```
+
+### Further Configuration And Usage
+
+```go
 // Additional properties can be configured for purposes of automated documentation.
 u.SetTitle("Doubler")
 u.SetDescription("Doubler doubles parameter values.")

generic_go1.18.go

@@ -0,0 +1,48 @@
+//go:build go1.18
+// +build go1.18
+
+package usecase
+
+import (
+	"context"
+	"fmt"
+)
+
+type IOInteractorOf[i, o interface{}] struct {
+	IOInteractor
+
+	InteractFunc func(ctx context.Context, input i, output *o) error
+}
+
+func (ioi IOInteractorOf[i, o]) Invoke(ctx context.Context, input i, output *o) error {
+	return ioi.InteractFunc(ctx, input, output)
+}
+
+// NewInteractor creates generic use case interactor with input and output ports.
+//
+// It pre-fills name and title with caller function.
+// Input is passed by value, while output is passed by pointer to be mutable.
+func NewInteractor[i, o any](interact func(ctx context.Context, input i, output *o) error) IOInteractorOf[i, o] {
+	u := IOInteractorOf[i, o]{}
+	u.Input = *new(i)
+	u.Output = new(o)
+	u.InteractFunc = interact
+	u.Interactor = Interact(func(ctx context.Context, input, output interface{}) error {
+		inp, ok := input.(i)
+		if !ok {
+			return fmt.Errorf("invalid input type received: %T, expected: %T", input, u.Input)
+		}
+
+		out, ok := output.(*o)
+		if !ok {
+			return fmt.Errorf("invalid output type received: %T, expected: %T", output, u.Output)
+		}
+
+		return interact(ctx, inp, out)
+	})
+
+	u.name, u.title = callerFunc()
+	u.name = filterName(u.name)
+
+	return u
+}

generic_go1.18_test.go

@@ -0,0 +1,50 @@
+//go:build go1.18
+// +build go1.18
+
+package usecase_test
+
+import (
+	"context"
+	"strconv"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/swaggest/usecase"
+)
+
+func TestNewIOI_classic(t *testing.T) {
+	u := usecase.NewIOI(*new(int), new(string), func(ctx context.Context, input, output interface{}) error {
+		in := input.(int)
+		out := output.(*string)
+
+		*out = strconv.Itoa(in)
+
+		return nil
+	})
+
+	ctx := context.Background()
+
+	var out string
+	assert.NoError(t, u.Interact(ctx, 123, &out))
+	assert.Equal(t, "123", out)
+}
+
+func TestNewInteractor(t *testing.T) {
+	u := usecase.NewInteractor(func(ctx context.Context, input int, output *string) error {
+		*output = strconv.Itoa(input)
+
+		return nil
+	})
+
+	u.SetDescription("Foo.")
+
+	ctx := context.Background()
+
+	var out string
+	assert.NoError(t, u.Interact(ctx, 123, &out))
+	assert.Equal(t, "123", out)
+
+	out = ""
+	assert.NoError(t, u.Invoke(ctx, 123, &out))
+	assert.Equal(t, "123", out)
+}

go.mod

@@ -1,8 +1,14 @@
 module github.com/swaggest/usecase
 
-go 1.12
+go 1.18
 
 require (
-	github.com/bool64/dev v0.1.41
+	github.com/bool64/dev v0.1.42
 	github.com/stretchr/testify v1.4.0
 )
+
+require (
+	github.com/davecgh/go-spew v1.1.0 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	gopkg.in/yaml.v2 v2.2.2 // indirect
+)

go.sum

@@ -1,5 +1,5 @@
-github.com/bool64/dev v0.1.41 h1:L554LCQZc3d7mtcdPUgDbSrCVbr48/30zgu0VuC/FTA=
-github.com/bool64/dev v0.1.41/go.mod h1:cTHiTDNc8EewrQPy3p1obNilpMpdmlUesDkFTF2zRWU=
+github.com/bool64/dev v0.1.42 h1:Ps0IvNNf/v1MlIXt8Q5YKcKjYsIVLY/fb/5BmA7gepg=
+github.com/bool64/dev v0.1.42/go.mod h1:cTHiTDNc8EewrQPy3p1obNilpMpdmlUesDkFTF2zRWU=
 github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=

interactor.go

@@ -184,10 +184,7 @@ func NewIOI(input, output interface{}, interact Interact) IOInteractor {
 	u.Interactor = interact
 
 	u.name, u.title = callerFunc()
-
-	u.name = strings.TrimPrefix(u.name, "internal/")
-	u.name = strings.TrimPrefix(u.name, "usecase.")
-	u.name = strings.TrimPrefix(u.name, "./main.")
+	u.name = filterName(u.name)
 
 	return u
 }
@@ -199,6 +196,14 @@ var titleReplacer = strings.NewReplacer(
 	")", "",
 )
 
+func filterName(name string) string {
+	name = strings.TrimPrefix(name, "internal/")
+	name = strings.TrimPrefix(name, "usecase.")
+	name = strings.TrimPrefix(name, "./main.")
+
+	return name
+}
+
 // callerFunc returns trimmed path and name of parent function.
 func callerFunc() (string, string) {
 	skipFrames := 2