Update README and example codes so it compiles correctly

README.md

@@ -93,21 +93,29 @@ import (
 And then in your main function initialize the metrics
 
 ``` go
+	shutdown, err := autometrics.Init()
+	if err != nil {
+		log.Fatalf("could not initialize autometrics: %s", err)
+	}
+	defer shutdown(nil)
+```
+
+`Init` takes optional arguments to customize the metrics. The main ones are `WithBranch`, 
+`WithService`, `WithVersion`, and `WithCommit`; it will add relevant information on the
+metrics for better intelligence:
+
+```go
 	shutdown, err := autometrics.Init(
-		nil,
-		autometrics.DefBuckets,
-		autometrics.BuildInfo{Version: "0.4.0", Commit: "anySHA", Branch: "", Service: "myApp"},
-		nil,
-		nil,
+		autometrics.WithService("myApp"),
+		autometrics.WithVersion("0.4.0"),
 	)
 	if err != nil {
 		log.Fatalf("could not initialize autometrics: %s", err)
 	}
 	defer shutdown(nil)
 ```
 
-Everything in `BuildInfo` is optional. It will add relevant information on the
-metrics for better intelligence. You can use any string variable whose value is
+You can use any string variable whose value is
 injected at build time by `ldflags` for example, or use environment variables.
 
 > **Note**
@@ -270,11 +278,9 @@ import (
 
 func main() {
 	shutdown, err := autometrics.Init(
-		nil,
-		autometrics.DefBuckets,
-		autometrics.BuildInfo{Version: "0.4.0", Commit: "anySHA", Branch: "", Service: "myApp"},
-		nil,
-		nil,
+		autometrics.WithVersion("0.4.0"),
+		autometrics.WithCommit("anySHA"),
+		autometrics.WithService("myApp"),
 	)
 	http.Handle("/metrics", promhttp.Handler())
 }
@@ -375,18 +381,18 @@ import (
 +	"github.com/autometrics-dev/autometrics-go/otel/autometrics"
 )
 ```
-- change the call to `autometrics.Init` to the new signature: instead of a registry,
+- maybe change the call to `autometrics.Init` to the new signature: instead of a registry,
 the `Init` function takes a meter name for the `otel_scope` label of the exported
-metric. You can use the name of the application or its version for example
+metric. That means `autometrics` won't have a `WithRegistry` option anymore, but a 
+`WithMeterName` instead.
 
 ``` patch
 	shutdown, err := autometrics.Init(
--		nil,
-+		"myApp/v2/prod",
-		autometrics.DefBuckets,
-		autometrics.BuildInfo{ Version: "2.1.37", Commit: "anySHA", Branch: "", Service: "myApp" },
-		nil,
-		nil,
+-		autometrics.WithRegistry(nil),
++		autometrics.WithMeterName("myApp/v2/prod"),
+		autometrics.WithVersion("2.1.37"),
+		autimetrics.WithCommit("anySHA"),
+		autometrics.WithService("myApp"),
 	)
 ```
 
@@ -436,21 +442,17 @@ If you have a Prometheus [push
 gateway](https://prometheus.io/docs/instrumenting/pushing/) or an OTLP
 [collector](https://opentelemetry.io/docs/collector/) setup with an accessible
 URL, then you can directly switch from metric polling to metric pushing by
-passing a non `nil` argument to `autometrics.Init` for the `pushConfiguration`:
+passing the push-related options to `autometrics.Init`:
 
 ``` patch
 	shutdown, err := autometrics.Init(
-		"myApp/v2/prod",
-		autometrics.DefBuckets,
-		autometrics.BuildInfo{ Version: "2.1.37", Commit: "anySHA", Branch: "", Service: "myApp" },
--		nil,
-+		&autometrics.PushConfiguration{
-+			CollectorURL: "https://collector.example.com",
-+			JobName: "instance_2",                         // You can leave the JobName out to let autometrics generate one
-+			Period: 1 * time.Second,                       // Period is only relevant when using OpenTelemetry implementation
-+			Timeout: 500 * time.Millisecond,               // Timeout is only relevant when using OpenTelementry implementation
-+		},
-    nil,
+		autometrics.WithMeterName("myApp/v2/prod"),
+		autometrics.WithVersion("2.1.37"),
+		autometrics.WithService("myApp"),
++		 autometrics.WithPushCollectorURL("https://collector.example.com"),
++		 autometrics.WithPushJobName("instance_2"),                         // You can leave the JobName out to let autometrics generate one
++		 autometrics.WithPushPeriod(1 * time.Second),                       // Period is only relevant (and available) when using OpenTelemetry implementation
++		 autometrics.WithPushTimeout(500 * time.Millisecond),               // Timeout is only relevant (and available) when using OpenTelementry implementation
 	)
 ```
 
@@ -480,12 +482,10 @@ the `Init` call:
 
 ``` patch
 	shutdown, err := autometrics.Init(
-		nil,
-		autometrics.DefBuckets,
-		autometrics.BuildInfo{ Version: "2.1.37", Commit: "anySHA", Branch: "", Service: "myApp" },
-		nil,
--		nil,
-+   autometrics.PrintLogger{},
+		autometrics.WithMeterName("myApp/v2/prod"),
+		autometrics.WithVersion("2.1.37"),
+		autometrics.WithService("myApp"),
++		 autometrics.WithLogger(autometrics.PrintLogger{}),
 	)
 ```
 

examples/otel/cmd/main.go

@@ -26,33 +26,32 @@ var (
 func main() {
 	rand.Seed(time.Now().UnixNano())
 
-	var pushConfiguration *autometrics.PushConfiguration
+	autometricsInitOpts := make([]autometrics.InitOption, 0)
+
 	if os.Getenv("AUTOMETRICS_OTLP_URL") != "" {
-		pushConfiguration = &autometrics.PushConfiguration{
-			CollectorURL: os.Getenv("AUTOMETRICS_OTLP_URL"),
+		autometricsInitOpts = append(autometricsInitOpts,
+			autometrics.WithPushCollectorURL(os.Getenv("AUTOMETRICS_OTLP_URL")),
 			// NOTE: Setting the JobName is useful when you fully control the instances that will run it.
 			//   Otherwise (auto-scaling scenarii), it's better to leave this value out, and let
 			//   autometrics generate an IP-based or Ulid-based identifier for you.
-			// JobName:      "autometrics_go_otel_example",
-			Period:  1 * time.Second,
-			Timeout: 500 * time.Millisecond,
-		}
+			// autometrics.WithPushJobName("autometrics_go_otel_example"),
+			autometrics.WithPushPeriod(1*time.Second),
+			autometrics.WithPushTimeout(500*time.Millisecond),
+		)
 	}
 
-	// Everything in BuildInfo is optional.
+	// Every option customization is optional.
 	// You can also use any string variable whose value is
 	// injected at build time by ldflags.
-	shutdown, err := autometrics.Init(
-		"web-server-go-component",
-		autometrics.DefBuckets,
-		autometrics.BuildInfo{
-			Version: Version,
-			Commit:  Commit,
-			Branch:  Branch,
-		},
-		pushConfiguration,
-		autometrics.PrintLogger{},
+	autometricsInitOpts = append(autometricsInitOpts,
+		autometrics.WithMeterName("web-server-go-component"),
+		autometrics.WithBranch(Branch),
+		autometrics.WithCommit(Commit),
+		autometrics.WithVersion(Version),
+		autometrics.WithLogger(autometrics.PrintLogger{}),
 	)
+
+	shutdown, err := autometrics.Init(autometricsInitOpts...)
 	if err != nil {
 		log.Fatalf("Failed initialization of autometrics: %s", err)
 	}

examples/web/cmd/main.go

@@ -28,30 +28,31 @@ var (
 func main() {
 	rand.Seed(time.Now().UnixNano())
 
+	autometricsInitOpts := make([]autometrics.InitOption, 0, 6)
+
 	// Allow the application to use a push gateway with an environment variable
 	// In production, you would do it with a command-line flag.
-	var pushConfiguration *autometrics.PushConfiguration
 	if os.Getenv("AUTOMETRICS_PUSH_GATEWAY_URL") != "" {
-		pushConfiguration = &autometrics.PushConfiguration{
-			CollectorURL: os.Getenv("AUTOMETRICS_PUSH_GATEWAY_URL"),
-			JobName:      "autometrics_go_test",
-		}
+		autometricsInitOpts = append(autometricsInitOpts,
+			autometrics.WithPushCollectorURL(os.Getenv("AUTOMETRICS_PUSH_GATEWAY_URL")),
+			// NOTE: Setting the JobName is useful when you fully control the instances that will run it.
+			//   Otherwise (auto-scaling scenarii), it's better to leave this value out, and let
+			//   autometrics generate an IP-based or Ulid-based identifier for you.
+			autometrics.WithPushJobName("autometrics_go_test"),
+		)
 	}
 
-	// Everything in BuildInfo is optional.
+	// Every option customization is optional.
 	// You can also use any string variable whose value is
 	// injected at build time by ldflags.
-	shutdown, err := autometrics.Init(
-		nil,
-		autometrics.DefBuckets,
-		autometrics.BuildInfo{
-			Version: Version,
-			Commit:  Commit,
-			Branch:  Branch,
-		},
-		pushConfiguration,
-		autometrics.PrintLogger{},
+	autometricsInitOpts = append(autometricsInitOpts,
+		autometrics.WithVersion(Version),
+		autometrics.WithCommit(Commit),
+		autometrics.WithBranch(Branch),
+		autometrics.WithLogger(autometrics.PrintLogger{}),
 	)
+
+	shutdown, err := autometrics.Init(autometricsInitOpts...)
 	if err != nil {
 		log.Fatalf("Failed initialization of autometrics: %s", err)
 	}

examples/web/cmd/main.go.orig

@@ -27,31 +27,31 @@ var (
 func main() {
 	rand.Seed(time.Now().UnixNano())
 
+	autometricsInitOpts := make([]autometrics.InitOption, 0, 6)
+
 	// Allow the application to use a push gateway with an environment variable
 	// In production, you would do it with a command-line flag.
-	var pushConfiguration *autometrics.PushConfiguration
 	if os.Getenv("AUTOMETRICS_PUSH_GATEWAY_URL") != "" {
-		pushConfiguration = &autometrics.PushConfiguration{
-			CollectorURL: os.Getenv("AUTOMETRICS_PUSH_GATEWAY_URL"),
-			JobName:      "autometrics_go_test",
-		}
+		autometricsInitOpts = append(autometricsInitOpts,
+			autometrics.WithPushCollectorURL(os.Getenv("AUTOMETRICS_PUSH_GATEWAY_URL")),
+			// NOTE: Setting the JobName is useful when you fully control the instances that will run it.
+			//   Otherwise (auto-scaling scenarii), it's better to leave this value out, and let
+			//   autometrics generate an IP-based or Ulid-based identifier for you.
+			autometrics.WithPushJobName("autometrics_go_test"),
+		)
 	}
 
-	// Everything in BuildInfo is optional.
+	// Every option customization is optional.
 	// You can also use any string variable whose value is
 	// injected at build time by ldflags.
-	shutdown, err := autometrics.Init(
-		nil,
-		autometrics.DefBuckets,
-		autometrics.BuildInfo{
-			Version: Version,
-			Commit:  Commit,
-			Branch:  Branch,
-			Service: "autometrics-go-example-prometheus"
-		},
-		pushConfiguration,
-		autometrics.PrintLogger{},
+	autometricsInitOpts = append(autometricsInitOpts,
+		autometrics.WithVersion(Version),
+		autometrics.WithCommit(Commit),
+		autometrics.WithBranch(Branch),
+		autometrics.WithLogger(autometrics.PrintLogger{}),
 	)
+
+	shutdown, err := autometrics.Init(autometricsInitOpts...)
 	if err != nil {
 		log.Fatalf("Failed initialization of autometrics: %s", err)
 	}