Исходники и презентации

lessons/contexts/context_with_value_inheritance/main.go

@@ -0,0 +1,26 @@
+package main
+
+import (
+	"context"
+	"fmt"
+)
+
+func main() {
+	traceCtx := context.WithValue(context.Background(), "trace_id", "12-21-33")
+	makeRequest(traceCtx)
+}
+
+func makeRequest(ctx context.Context) {
+	oldValue, ok := ctx.Value("trace_id").(string)
+	if ok {
+		fmt.Println(oldValue)
+	}
+
+	newCtx, cancel := context.WithCancel(ctx)
+	defer cancel()
+
+	newValue, ok := newCtx.Value("trace_id").(string)
+	if ok {
+		fmt.Println(newValue)
+	}
+}