Add example with lua built-in function

* Move examples from cmd to examples dir
* Update Makefile
* LoadJsonFile() dies in-place on read or parse error which is not correct
* LoadJsonFile() wastes Instance map, now it returns its own map and error if any

.gitignore

@@ -1,2 +1,6 @@
 /01-LoadJsonFile
+/02-TestLuaScript
+/03-UseGoFuncInLua
+/doll
+/doll-master
 /*.exe

Makefile

@@ -2,21 +2,20 @@
 
 GOOPTS=CGO_ENABLED=0
 BUILDOPTS=-ldflags="-s -w" -a -gcflags=all=-l -trimpath -buildvcs=false
-MYNAME1=doll
+MYNAME1=doll-master
-MYNAME2=doll-master
 BINARY1=${MYNAME1}
-BINARY2=${MYNAME2}
 UNIX_BINARY1=${MYNAME1}
-UNIX_BINARY2=${MYNAME2}
 WINDOWS_BINARY1=${MYNAME1}.exe
+MYNAME2=doll
+BINARY2=${MYNAME2}
+UNIX_BINARY2=${MYNAME2}
 WINDOWS_BINARY2=${MYNAME2}.exe
+RMCMD=rm -rf
 EXAMPLE01=01-LoadJsonFile
 EXAMPLE02=02-TestLuaScript
+EXAMPLE03=03-UseGoFuncInLua
 
-RMCMD=rm -rf
+# On windows binary name can depend not only on platform selected, but target too, we need no .exe suffix for linux bin.
-
-# На windows имя бинарника может зависеть не только от платформы, но и от выбранной цели, для linux-а суффикс .exe
-# не нужен
 ifeq ($(OS),Windows_NT)
 ifdef GOOS
 ifeq ($(GOOS),windows)
@@ -35,7 +34,7 @@ RMCMD=DEL /Q /F
 endif
 endif
 
-# Явно определяем символ новой строки, чтобы избежать неоднозначности на windows
+# Set newline symbol explicitly to aboud undefined behaviour in windows.
 define IFS
 
 endef
@@ -63,7 +62,7 @@ else  # not ifeq (,$(findstring(Git/usr/bin/sh.exe, $(SHELL))))
 endif # ifeq (,$(findstring(Git/usr/bin/sh.exe, $(SHELL))))
 else  # not  ($(OS),Windows_NT)
 	CGO_ENABLED=0 go build ${BUILDOPTS} -o ${BINARY1} ./cmd/${MYNAME1}
-	CGO_ENABLED=0 go build ${BUILDOPTS} -o ${BINARY2} ./cmd/${MYNAME2}
+	CGO_ENABLED=0 go build ${BUILDOPTS} -o ${BINARY1} ./cmd/${MYNAME2}
 endif # ifeq ($(OS),Windows_NT)
 
 
@@ -71,29 +70,33 @@ clean:
 ifeq ($(OS),Windows_NT)
 ifeq ($(SHELL),sh.exe)
 #	# Vanilla cmd.exe / powershell.
-	if exist 01-LoadJsonFile.exe ${RMCMD} ${WINDOWS_BINARY1}
+	if exist ${WINDOWS_BINARY1} ${RMCMD} ${WINDOWS_BINARY1}
-	if exist 01-LoadJsonFile.exe ${RMCMD} ${UNIX_BINARY1}
+	if exist ${UNIX_BINARY1} ${RMCMD} ${UNIX_BINARY1}
-	if exist 01-LoadJsonFile.exe ${RMCMD} ${WINDOWS_BINARY2}
+	if exist ${WINDOWS_BINARY2} ${RMCMD} ${WINDOWS_BINARY2}
-	if exist 01-LoadJsonFile.exe ${RMCMD} ${UNIX_BINARY2}
+	if exist ${EXAMPLE01}.exe ${RMCMD} ${EXAMPLE01}.exe
-	if exist 01-LoadJsonFile.exe ${RMCMD} 01-LoadJsonFile.exe
+	if exist ${EXAMPLE01} ${RMCMD} ${EXAMPLE01}
-	if exist 01-LoadJsonFile ${RMCMD} 01-LoadJsonFile
+	if exist ${EXAMPLE02}.exe ${RMCMD} ${EXAMPLE02}.exe
-	if exist 02-TestLuaScript.exe ${RMCMD} 02-TestLuaScript.exe
+	if exist ${EXAMPLE02} ${RMCMD} ${EXAMPLE02}
-	if exist 02-TestLuaScript ${RMCMD} 02-TestLuaScript
+		if exist ${EXAMPLE03}.exe ${RMCMD} ${EXAMPLE03}.exe
+	if exist ${EXAMPLE03} ${RMCMD} ${EXAMPLE03}
 else  # not ifeq ($(SHELL),sh.exe)
-	${RMCMD} ${WINDOWS_BINARY1}
+	${RMCMD} ./${WINDOWS_BINARY1}
-	${RMCMD} ${UNIX_BINARY1}
+	${RMCMD} ./${UNIX_BINARY1}
-	${RMCMD} ${WINDOWS_BINARY2}
+	${RMCMD} ./${WINDOWS_BINARY2}
-	${RMCMD} ${UNIX_BINARY2}
+	${RMCMD} ./${UNIX_BINARY2}
-	${RMCMD} ./01-LoadJsonFile.exe
+	${RMCMD} ./${EXAMPLE01}.exe
-	${RMCMD} ./01-LoadJsonFile
+	${RMCMD} ./${EXAMPLE01}
-	${RMCMD} ./02-TestLuaScript.exe
+	${RMCMD} ./${EXAMPLE02}.exe
-	${RMCMD} ./02-TestLuaScript
+	${RMCMD} ./${EXAMPLE02}
+	${RMCMD} ./${EXAMPLE03}.exe
+	${RMCMD} ./${EXAMPLE03}
 endif # ifeq ($(SHELL),sh.exe)
 else  # not ifeq ($(OS),Windows_NT)
-	${RMCMD} ${BINARY1}
+	${RMCMD} ./${UNIX_BINARY1}
-	${RMCMD} ${BINARY2}
+	${RMCMD} ./${UNIX_BINARY2}
-	${RMCMD} ./01-LoadJsonFile
+	${RMCMD} ${EXAMPLE01}
-	${RMCMD} ./02-TestLuaScript
+	${RMCMD} ${EXAMPLE02}
+	${RMCMD} ${EXAMPLE03}
 endif
 
 
@@ -103,43 +106,63 @@ upgrade:
 	go mod vendor
 
 
-01-LoadJsonFile: clean
+${EXAMPLE01}: clean
 ifeq ($(OS),Windows_NT)
 # Looks like on windows gnu make explicitly set SHELL to sh.exe, if it was not set.
 ifeq ($(SHELL), sh.exe)
 #       # Vanilla cmd.exe / powershell.
 	SET "CGO_ENABLED=0"
-	go build ${BUILDOPTS} -o ${EXAMPLE01}.exe ./examples/${EXAMPLE01}
+	go build ${BUILDOPTS} -o ${EXAMPLE01}.exe ./cmd/${EXAMPLE01}
 else ifeq (,$(findstring(Git/usr/bin/sh.exe, $(SHELL))))
 #       # git-bash
-	CGO_ENABLED=0 go build ${BUILDOPTS} -o ${EXAMPLE01}.exe ./examples/${EXAMPLE01}
+	CGO_ENABLED=0 go build ${BUILDOPTS} -o ${EXAMPLE01}.exe ./cmd/${EXAMPLE01}
 else  # not ifeq (,$(findstring(Git/usr/bin/sh.exe, $(SHELL))))
 #       # Some other shell.
 #       # TODO: handle it.
 	$(info "-- Dunno how to handle this shell: ${SHELL}")
 endif # ifeq (,$(findstring(Git/usr/bin/sh.exe, $(SHELL))))
 else  # not  ($(OS),Windows_NT)
-	CGO_ENABLED=0 go build ${BUILDOPTS} -o ${EXAMPLE01} ./examples/${EXAMPLE01}
+	CGO_ENABLED=0 go build ${BUILDOPTS} -o ${EXAMPLE01} ./cmd/${EXAMPLE01}
 endif # ifeq ($(OS),Windows_NT)
 
 
-02-TestLuaScript: clean
+${EXAMPLE02}: clean
 ifeq ($(OS),Windows_NT)
 # Looks like on windows gnu make explicitly set SHELL to sh.exe, if it was not set.
 ifeq ($(SHELL), sh.exe)
 #       # Vanilla cmd.exe / powershell.
 	SET "CGO_ENABLED=0"
-	go build ${BUILDOPTS} -o ${EXAMPLE02}.exe ./examples/${EXAMPLE02}
+	go build ${BUILDOPTS} -o ${EXAMPLE02}.exe ./cmd/${EXAMPLE02}
 else ifeq (,$(findstring(Git/usr/bin/sh.exe, $(SHELL))))
 #       # git-bash
-	CGO_ENABLED=0 go build ${BUILDOPTS} -o ${EXAMPLE02}.exe ./examples/${EXAMPLE02}
+	CGO_ENABLED=0 go build ${BUILDOPTS} -o ${EXAMPLE02}.exe ./cmd/${EXAMPLE02}
 else  # not ifeq (,$(findstring(Git/usr/bin/sh.exe, $(SHELL))))
 #       # Some other shell.
 #       # TODO: handle it.
 	$(info "-- Dunno how to handle this shell: ${SHELL}")
 endif # ifeq (,$(findstring(Git/usr/bin/sh.exe, $(SHELL))))
 else  # not  ($(OS),Windows_NT)
-	CGO_ENABLED=0 go build ${BUILDOPTS} -o ${EXAMPLE02} ./examples/${EXAMPLE02}
+	CGO_ENABLED=0 go build ${BUILDOPTS} -o ${EXAMPLE02} ./cmd/${EXAMPLE02}
+endif # ifeq ($(OS),Windows_NT)
+
+
+${EXAMPLE03}: clean
+ifeq ($(OS),Windows_NT)
+# Looks like on windows gnu make explicitly set SHELL to sh.exe, if it was not set.
+ifeq ($(SHELL), sh.exe)
+#       # Vanilla cmd.exe / powershell.
+	SET "CGO_ENABLED=0"
+	go build ${BUILDOPTS} -o ${EXAMPLE03}.exe ./cmd/${EXAMPLE03}
+else ifeq (,$(findstring(Git/usr/bin/sh.exe, $(SHELL))))
+#       # git-bash
+	CGO_ENABLED=0 go build ${BUILDOPTS} -o ${EXAMPLE03}.exe ./cmd/${EXAMPLE03}
+else  # not ifeq (,$(findstring(Git/usr/bin/sh.exe, $(SHELL))))
+#       # Some other shell.
+#       # TODO: handle it.
+	$(info "-- Dunno how to handle this shell: ${SHELL}")
+endif # ifeq (,$(findstring(Git/usr/bin/sh.exe, $(SHELL))))
+else  # not  ($(OS),Windows_NT)
+	CGO_ENABLED=0 go build ${BUILDOPTS} -o ${EXAMPLE03} ./cmd/${EXAMPLE03}
 endif # ifeq ($(OS),Windows_NT)
 
 

example_data/02-test.lua

@@ -1,3 +1,3 @@
 print ("Hello World!")
 
--- vim: set ft=go noet ai ts=4 sw=4 sts=4:
+-- vim: set ft=lua noet ai ts=4 sw=4 sts=4:

example_data/03-test.lua

@@ -0,0 +1,3 @@
+print("4 * 4 = " .. square(4))
+
+-- vim: set ft=lua noet ai ts=4 sw=4 sts=4:

examples/01-LoadJsonFile/main.go

@@ -9,14 +9,21 @@ import (
 )
 
 func main() {
+	// Init log subsystem.
+	log.Init("info", os.Stderr)
+
 	file := "example_data/01-config.json"
 
-	log.Init("info", os.Stderr)
+	// Load the Lua script file.
-	log.Infof("loading %s", file)
+	log.Infof("Loading %s", file)
 
-	data := doll.LoadJsonFile(file)
+	data, err := doll.LoadJsonFile(file)
 
-	log.Infof("data from %s", file)
+	if err != nil {
+		log.Fatalf("Unable to unmarshal %s to map: %s", file, err)
+	}
+
+	log.Infof("Map unmarshalled from %s", file)
 
 	spew.Dump(data)
 }

examples/02-TestLuaScript/main.go

@@ -8,11 +8,10 @@ import (
 )
 
 func main() {
-	file := "example_data/02-test.lua"
+	// Init log subsystem.
 	log.Init("info", os.Stderr)
 
-	L := lua.NewState()
+	file := "example_data/02-test.lua"
-	defer L.Close()
 
 	// Load the Lua script file.
 	log.Infof("Loading %s", file)
@@ -22,15 +21,16 @@ func main() {
 	luaCode, err := os.ReadFile(file)
 
 	if err != nil {
-		log.Errorf("Error reading Lua file %s: %s", file, err)
+		log.Fatalf("Error reading Lua file %s: %s", file, err)
-
-		os.Exit(1)
 	}
 
-	if err := L.DoString(string(luaCode)); err != nil {
+	log.Info("Creating new Lua state")
-		log.Errorf("Error evaluating Lua code: %s", err)
+	L := lua.NewState()
+	defer L.Close()
 
-		os.Exit(1)
+	log.Info("Evaluating Lua code")
+	if err := L.DoString(string(luaCode)); err != nil {
+		log.Fatalf("Error evaluating Lua code: %s", err)
 	}
 }
 

examples/03-UseGoFuncInLua/main.go

@@ -0,0 +1,59 @@
+package main
+
+// This exmple taken from https://otm.github.io/2015/07/embedding-lua-in-go/ .
+
+import (
+	"doll/internal/log"
+	"os"
+
+	lua "github.com/yuin/gopher-lua"
+)
+
+// square multiplies number by itself.
+func square(L *lua.LState) int {
+	// get first (1) function argument and convert to int
+	i := L.ToInt(1)
+
+	// make calculation and cast to LNumber
+	ln := lua.LNumber(i * i)
+
+	// Push it to the stack
+	L.Push(ln)
+
+	// Notify that we pushed one value to the stack
+	return 1
+}
+
+func main() {
+	// Init log subsystem.
+	log.Init("info", os.Stderr)
+
+	file := "example_data/03-test.lua"
+
+	// Load the Lua script file.
+	log.Infof("Loading %s", file)
+
+	// We can execute script directly via L.DoFile("./example_data/03-test.lua") but in practice we'll get scripts as
+	// strings - snippets from templates - so, testing/checking how it works is not use for project.
+	luaCode, err := os.ReadFile(file)
+
+	if err != nil {
+		log.Fatalf("Error reading Lua file %s: %s", file, err)
+	}
+
+	log.Info("Creating new Lua state")
+	L := lua.NewState()
+	defer L.Close()
+
+	log.Info("Registering go function as lua built-in function")
+	L.SetGlobal("square", L.NewFunction(square))
+
+	log.Info("Evaluating Lua code")
+	if err := L.DoString(string(luaCode)); err != nil {
+		log.Errorf("Error evaluating Lua code: %s", err)
+
+		os.Exit(1)
+	}
+}
+
+/* vim: set ft=go noet ai ts=4 sw=4 sts=4: */

internal/doll/jsonfile.go

@@ -1,30 +1,30 @@
 package doll
 
 import (
-	"doll/internal/log"
 	"encoding/json"
+	"fmt"
 	"os"
 )
 
 // LoadJsonFile loads data from json to Instance global variable map.
-func LoadJsonFile(file string) map[string]any {
+func LoadJsonFile(file string) (map[string]any, error) {
 	var (
-		err  error
+		err   error
-		data []byte
+		data  []byte
+		myMap map[string]any
 	)
 
 	data, err = os.ReadFile(file)
 
 	if err != nil {
-		log.Fatalf("Unable to load %s: %s", file, err)
+		return myMap, fmt.Errorf("Unable to load %s: %w", file, err)
 	}
 
-	err = json.Unmarshal([]byte(data), &Instance)
+	if err = json.Unmarshal([]byte(data), &myMap); err != nil {
-	if err != nil {
+		return myMap, fmt.Errorf("Unable to unmarshal JSON data from %s: %w", file, err)
-		log.Fatalf("Unable to marshal JSON data from %s: %s", file, err)
 	}
 
-	return Instance
+	return myMap, err
 }
 
 /* vim: set ft=go noet ai ts=4 sw=4 sts=4: */

internal/serverConfig/readConfig.go

@@ -1,4 +1,4 @@
-package serverConfig
+package serverSonfig
 
 import (
 	"encoding/json"