Add loggers that take functions as input

example_function_test.go

@@ -0,0 +1,26 @@
+package logrus_test
+
+import (
+	"fmt"
+	log "github.com/sirupsen/logrus"
+	"testing"
+)
+
+func TestLogger_LogFn(t *testing.T) {
+	log.SetFormatter(&log.JSONFormatter{})
+	log.SetLevel(log.WarnLevel)
+
+	log.InfoFn(func() []interface{} {
+		fmt.Println("This is never run")
+		return []interface{} {
+			"Hello",
+		}
+	})
+
+	log.ErrorFn(func() []interface{} {
+		fmt.Println("This runs")
+		return []interface{} {
+			"Oopsi",
+		}
+	})
+}