flag<\/code> Paketi Nas\u0131l Kullan\u0131l\u0131r: Komut Sat\u0131r\u0131 Arg\u00fcmanlar\u0131n\u0131 Y\u00f6netmek<\/h2>\nGiri\u015f<\/h2>\n
Go programlama dili, uygulamalar\u0131n komut sat\u0131r\u0131 arg\u00fcmanlar\u0131n\u0131 kolayca ayr\u0131\u015ft\u0131rmas\u0131 ve y\u00f6netmesi i\u00e7in standart k\u00fct\u00fcphanesinde g\u00fc\u00e7l\u00fc ve kullan\u0131m\u0131 basit bir paket olan flag<\/code> paketini sunar. Modern uygulamalar\u0131n \u00e7o\u011fu, kullan\u0131c\u0131dan veya otomasyon sistemlerinden gelen girdileri i\u015flemek i\u00e7in komut sat\u0131r\u0131 arg\u00fcmanlar\u0131na ihtiya\u00e7 duyar. Bu arg\u00fcmanlar genellikle yap\u0131land\u0131rma ayarlar\u0131n\u0131 (\u00f6rne\u011fin, veritaban\u0131 ba\u011flant\u0131 dizeleri), \u00e7al\u0131\u015fma zaman\u0131 se\u00e7eneklerini (\u00f6rne\u011fin, hata ay\u0131klama modu) veya belirli g\u00f6revleri (\u00f6rne\u011fin, dosya yollar\u0131) belirtmek i\u00e7in kullan\u0131l\u0131r. flag<\/code> paketi, bu t\u00fcr girdileri tan\u0131mlaman\u0131za, varsay\u0131lan de\u011ferler ataman\u0131za, a\u00e7\u0131klamalar eklemenize ve program\u0131n\u0131z\u0131n bu arg\u00fcmanlar\u0131 g\u00fcvenli bir \u015fekilde ayr\u0131\u015ft\u0131rmas\u0131na olanak tan\u0131r.<\/p>\nBu makalede, flag<\/code> paketinin temelden ileri seviyeye kadar nas\u0131l kullan\u0131laca\u011f\u0131n\u0131 ayr\u0131nt\u0131l\u0131 olarak inceleyece\u011fiz. De\u011fi\u015fken t\u00fcrlerine g\u00f6re bayrak tan\u0131mlamadan, \u00f6zel bayrak t\u00fcrleri olu\u015fturmaya, hata y\u00f6netimine ve alt komutlar i\u00e7in FlagSet<\/code> kullan\u0131m\u0131na kadar bir\u00e7ok konuyu ele alaca\u011f\u0131z. Amac\u0131m\u0131z, Go projelerinizde komut sat\u0131r\u0131 arg\u00fcmanlar\u0131n\u0131 etkin bir \u015fekilde y\u00f6netmek i\u00e7in ihtiyac\u0131n\u0131z olan t\u00fcm bilgileri size sunmakt\u0131r.<\/p>\nTemel Kullan\u0131m<\/h2>\n
flag<\/code> paketini kullanmaya ba\u015flamak olduk\u00e7a basittir. \u0130lk ad\u0131m, program\u0131n\u0131z\u0131n bekledi\u011fi bayraklar\u0131 (arg\u00fcmanlar\u0131) tan\u0131mlamak ve ard\u0131ndan bu bayraklar\u0131 ayr\u0131\u015ft\u0131rmak i\u00e7in flag.Parse()<\/code> fonksiyonunu \u00e7a\u011f\u0131rmakt\u0131r.<\/p>\nDe\u011fi\u015fken Tan\u0131mlama ve Bayrak Ba\u011flama<\/h3>\n
flag<\/code> paketi, farkl\u0131 veri t\u00fcrleri i\u00e7in bayraklar tan\u0131mlaman\u0131za olanak tan\u0131yan bir dizi fonksiyon sunar. En yayg\u0131n kullan\u0131lanlar flag.String<\/code>, flag.Int<\/code> ve flag.Bool<\/code>‘dur. Bu fonksiyonlar, bir bayrak tan\u0131mlar ve bu bayra\u011f\u0131n de\u011ferini tutacak bir de\u011fi\u015fkenin i\u015faret\u00e7isini (pointer) d\u00f6nd\u00fcr\u00fcr.<\/p>\nHer bir fonksiyon genellikle d\u00f6rt arg\u00fcman al\u0131r:<\/p>\n
\n- Bayra\u011f\u0131n ad\u0131 (\u00f6rne\u011fin, “name”, “port”, “verbose”).<\/li>\n
- Bayra\u011f\u0131n varsay\u0131lan de\u011feri. Kullan\u0131c\u0131 bu bayra\u011f\u0131 belirtmezse kullan\u0131lacak de\u011fer budur.<\/li>\n
- Bayra\u011f\u0131n k\u0131sa a\u00e7\u0131klamas\u0131. Bu a\u00e7\u0131klama,
flag.PrintDefaults()<\/code> veya -h<\/code>\/--help<\/code> ile otomatik olarak olu\u015fturulan kullan\u0131m mesaj\u0131nda g\u00f6sterilir.<\/li>\n<\/ol>\n\u0130\u015fte basit bir \u00f6rnek:<\/p>\n
package main\n\nimport (\n\t\"flag\"\n\t\"fmt\"\n)\n\nfunc main() {\n\t\/\/ String tipi bir bayrak tan\u0131mlama\n\tname := flag.String(\"name\", \"D\u00fcnya\", \"Selam verilecek isim\")\n\n\t\/\/ Integer tipi bir bayrak tan\u0131mlama\n\tport := flag.Int(\"port\", 8080, \"Uygulaman\u0131n \u00e7al\u0131\u015faca\u011f\u0131 port numaras\u0131\")\n\n\t\/\/ Boolean tipi bir bayrak tan\u0131mlama\n\tverbose := flag.Bool(\"verbose\", false, \"Detayl\u0131 \u00e7\u0131kt\u0131 g\u00f6stermek i\u00e7in\")\n\n\t\/\/ flag.Parse() \u00e7a\u011fr\u0131lmadan \u00f6nce bayraklar\u0131n varsay\u0131lan de\u011ferleri vard\u0131r.\n\tfmt.Printf(\"Ba\u015flang\u0131\u00e7 de\u011ferleri: name=%s, port=%d, verbose=%t\\n\", name, <\/em>port, *verbose)\n\n\t\/\/ Bayraklar\u0131 ayr\u0131\u015ft\u0131rma (komut sat\u0131r\u0131 arg\u00fcmanlar\u0131n\u0131 i\u015fleme)\n\tflag.Parse()\n\n\t\/\/ flag.Parse() \u00e7a\u011fr\u0131ld\u0131ktan sonra bayraklar\u0131n de\u011ferlerine eri\u015febiliriz.\n\t\/\/ D\u00f6nd\u00fcr\u00fclen i\u015faret\u00e7iyi (pointer) dereference etmeyi unutmay\u0131n.\n\tfmt.Printf(\"Merhaba, %s! Uygulama %d portunda \u00e7al\u0131\u015f\u0131yor. Detayl\u0131 mod: %t\\n\", name, <\/em>port, *verbose)\n}\n<\/code><\/pre>\nBu kodu derleyip \u00e7al\u0131\u015ft\u0131rd\u0131\u011f\u0131n\u0131zda:<\/p>\n
\ngo run main.go<\/code>: Merhaba, D\u00fcnya! Uygulama 8080 portunda \u00e7al\u0131\u015f\u0131yor. Detayl\u0131 mod: false<\/code><\/li>\ngo run main.go --name \"Go Programc\u0131s\u0131\" --port 9000 -verbose<\/code>: Merhaba, Go Programc\u0131s\u0131! Uygulama 9000 portunda \u00e7al\u0131\u015f\u0131yor. Detayl\u0131 mod: true<\/code><\/li>\ngo run main.go -h<\/code>: Tan\u0131mlad\u0131\u011f\u0131n\u0131z bayraklar\u0131n a\u00e7\u0131klamalar\u0131yla birlikte bir kullan\u0131m mesaj\u0131 g\u00f6r\u00fcrs\u00fcn\u00fcz.<\/li>\n<\/ul>\nAlternatif olarak, mevcut bir de\u011fi\u015fkeni bayra\u011fa ba\u011flamak i\u00e7in flag.StringVar<\/code>, flag.IntVar<\/code>, flag.BoolVar<\/code> gibi fonksiyonlar\u0131 kullanabilirsiniz. Bu, \u00f6zellikle yap\u0131land\u0131rma nesneleriyle \u00e7al\u0131\u015f\u0131rken faydal\u0131 olabilir:<\/p>\npackage main\n\nimport (\n\t\"flag\"\n\t\"fmt\"\n)\n\nfunc main() {\n\tvar name string\n\tvar port int\n\tvar verbose bool\n\n\tflag.StringVar(&name, \"name\", \"D\u00fcnya\", \"Selam verilecek isim\")\n\tflag.IntVar(&port, \"port\", 8080, \"Uygulaman\u0131n \u00e7al\u0131\u015faca\u011f\u0131 port numaras\u0131\")\n\tflag.BoolVar(&verbose, \"verbose\", false, \"Detayl\u0131 \u00e7\u0131kt\u0131 g\u00f6stermek i\u00e7in\")\n\n\tflag.Parse()\n\n\tfmt.Printf(\"Merhaba, %s! Uygulama %d portunda \u00e7al\u0131\u015f\u0131yor. Detayl\u0131 mod: %t\\n\", name, port, verbose)\n}\n<\/code><\/pre>\nHer iki y\u00f6ntem de ayn\u0131 sonucu verir; tercih genellikle ki\u015fisel kodlama stiline veya mevcut de\u011fi\u015fken yap\u0131s\u0131na ba\u011fl\u0131d\u0131r.<\/p>\n
Bayraklar\u0131 Ayr\u0131\u015ft\u0131rma (flag.Parse()<\/code>)<\/h3>\nflag.Parse()<\/code> fonksiyonu, flag<\/code> paketinin kalbidir. Bu fonksiyon, komut sat\u0131r\u0131 arg\u00fcmanlar\u0131n\u0131 tarar, tan\u0131mlanm\u0131\u015f bayraklar\u0131 bulur ve kar\u015f\u0131l\u0131k gelen de\u011fi\u015fkenlerin de\u011ferlerini g\u00fcnceller. T\u00fcm bayrak tan\u0131mlamalar\u0131 yap\u0131ld\u0131ktan sonra ve bayrak de\u011ferlerine eri\u015fmeden \u00f6nce flag.Parse()<\/code> \u00e7a\u011fr\u0131lmal\u0131d\u0131r.<\/strong> E\u011fer flag.Parse()<\/code> \u00e7a\u011fr\u0131lmazsa, bayrak de\u011fi\u015fkenleri varsay\u0131lan de\u011ferlerini korur ve komut sat\u0131r\u0131nda belirtilen de\u011ferler dikkate al\u0131nmaz.<\/p>\nflag.Parse()<\/code> \u00e7a\u011fr\u0131ld\u0131\u011f\u0131nda, os.Args<\/code> dilimini (slice) ayr\u0131\u015ft\u0131rmaya ba\u015flar. os.Args[0]<\/code> program\u0131n ad\u0131d\u0131r ve flag<\/code> paketi bunu g\u00f6z ard\u0131 eder. Kalan arg\u00fcmanlar, tan\u0131mlanm\u0131\u015f bayraklarla e\u015fle\u015ftirilir. E\u011fer bilinmeyen bir bayrak veya ge\u00e7ersiz bir de\u011fer format\u0131 ile kar\u015f\u0131la\u015f\u0131l\u0131rsa, flag<\/code> paketi varsay\u0131lan olarak bir hata mesaj\u0131 yazd\u0131r\u0131r ve programdan os.Exit(2)<\/code> ile \u00e7\u0131kar. Bu davran\u0131\u015f flag.Usage<\/code> de\u011fi\u015fkeni \u00f6zelle\u015ftirilerek de\u011fi\u015ftirilebilir.<\/p>\nflag.Parse()<\/code> fonksiyonundan sonra, bayraklar taraf\u0131ndan i\u015flenmeyen t\u00fcm kalan komut sat\u0131r\u0131 arg\u00fcmanlar\u0131na flag.Args()<\/code> fonksiyonu ile eri\u015filebilir. Bu, \u00f6zellikle bir komutun hem bayraklar\u0131 hem de pozisyonel arg\u00fcmanlar\u0131 (\u00f6rne\u011fin, dosya adlar\u0131 veya kimlikler) kabul etti\u011fi senaryolarda kullan\u0131\u015fl\u0131d\u0131r.<\/p>\npackage main\n\nimport (\n\t\"flag\"\n\t\"fmt\"\n)\n\nfunc main() {\n\tname := flag.String(\"name\", \"Anonim\", \"\u0130\u015flem yapacak ki\u015finin ad\u0131\")\n\t\n\tflag.Parse()\n\n\tfmt.Printf(\"\u0130\u015flem yapan: %s\\n\", *name)\n\n\t\/\/ Kalan arg\u00fcmanlara eri\u015fim\n\tif flag.NArg() > 0 {\n\t\tfmt.Println(\"Kalan arg\u00fcmanlar:\")\n\t\tfor i, arg := range flag.Args() {\n\t\t\tfmt.Printf(\" %d: %s\\n\", i+1, arg)\n\t\t}\n\t} else {\n\t\tfmt.Println(\"Hi\u00e7 kalan arg\u00fcman yok.\")\n\t}\n}\n<\/code><\/pre>\n\u00c7al\u0131\u015ft\u0131rma \u00f6rnekleri:<\/p>\n
\ngo run main.go<\/code>: \u0130\u015flem yapan: Anonim<\/code>, Hi\u00e7 kalan arg\u00fcman yok.<\/code><\/li>\ngo run main.go --name \"Alice\"<\/code>: \u0130\u015flem yapan: Alice<\/code>, Hi\u00e7 kalan arg\u00fcman yok.<\/code><\/li>\ngo run main.go file1.txt file2.txt --name \"Bob\"<\/code>: \u0130\u015flem yapan: Bob<\/code>, Kalan arg\u00fcmanlar: 1: file1.txt, 2: file2.txt<\/code> (Bayraklar her zaman arg\u00fcmanlardan \u00f6nce gelmeli, aksi takdirde bayrak olmayanlar arg\u00fcman olarak alg\u0131lan\u0131r. Do\u011frusu: go run main.go --name \"Bob\" file1.txt file2.txt<\/code>)<\/li>\n<\/ul>\nG\u00f6rd\u00fc\u011f\u00fcn\u00fcz gibi, flag.Parse()<\/code> t\u00fcm bayraklar\u0131 i\u015fler ve ard\u0131ndan kalan her \u015feyi flag.Args()<\/code>‘a b\u0131rak\u0131r.<\/p>\nBayrak T\u00fcrleri ve Kullan\u0131m Senaryolar\u0131<\/h2>\n
flag<\/code> paketi, Go’nun temel veri t\u00fcrlerine kar\u015f\u0131l\u0131k gelen bir\u00e7ok haz\u0131r bayrak t\u00fcr\u00fc sunar. Ayr\u0131ca, \u00f6zel veri t\u00fcrleriniz i\u00e7in kendi bayrak t\u00fcrlerinizi de tan\u0131mlayabilirsiniz.<\/p>\nString Bayraklar\u0131<\/h3>\n
En s\u0131k kullan\u0131lan bayrak t\u00fcrlerinden biridir. Metin tabanl\u0131 girdiler i\u00e7in kullan\u0131l\u0131r.<\/p>\n
\nflag.String(name string, value string, usage string) *string<\/code>: Yeni bir string bayrak tan\u0131mlar ve varsay\u0131lan de\u011feriyle birlikte bir i\u015faret\u00e7i d\u00f6nd\u00fcr\u00fcr.<\/li>\nflag.StringVar(p *string, name string, value string, usage string)<\/code>: Mevcut bir string de\u011fi\u015fkenini bir bayra\u011fa ba\u011flar.<\/li>\n<\/ul>\npackage main\n\nimport (\n\t\"flag\"\n\t\"fmt\"\n)\n\nfunc main() {\n\tvar configPath string\n\tflag.StringVar(&configPath, \"config\", \"\/etc\/app\/config.json\", \"Uygulama yap\u0131land\u0131rma dosyas\u0131n\u0131n yolu\")\n\n\tlogLevel := flag.String(\"log-level\", \"info\", \"Uygulama g\u00fcnl\u00fck seviyesi (debug, info, warn, error)\")\n\n\tflag.Parse()\n\n\tfmt.Printf(\"Yap\u0131land\u0131rma dosyas\u0131: %s\\n\", configPath)\n\tfmt.Printf(\"G\u00fcnl\u00fck seviyesi: %s\\n\", *logLevel)\n}\n<\/code><\/pre>\nKullan\u0131m: go run main.go --config \/opt\/app\/myconfig.json --log-level debug<\/code><\/p>\nInteger Bayraklar\u0131<\/h3>\n
Say\u0131sal de\u011ferler i\u00e7in kullan\u0131l\u0131r. int<\/code>, int64<\/code>, uint<\/code>, uint64<\/code> gibi farkl\u0131 tam say\u0131 t\u00fcrleri i\u00e7in fonksiyonlar mevcuttur.<\/p>\n\nflag.Int(name string, value int, usage string) *int<\/code><\/li>\nflag.IntVar(p *int, name string, value int, usage string)<\/code><\/li>\n- Benzer \u015fekilde
flag.Int64<\/code>, flag.IntVar64<\/code>, flag.Uint<\/code>, flag.UintVar<\/code>, flag.Uint64<\/code>, flag.UintVar64<\/code> fonksiyonlar\u0131 da bulunur.<\/li>\n<\/ul>\npackage main\n\nimport (\n\t\"flag\"\n\t\"fmt\"\n)\n\nfunc main() {\n\tmaxWorkers := flag.Int(\"workers\", 4, \"Ayn\u0131 anda \u00e7al\u0131\u015facak maksimum i\u015f\u00e7i say\u0131s\u0131\")\n\ttimeoutSeconds := flag.Uint(\"timeout\", 30, \"\u0130\u015flemler i\u00e7in saniye cinsinden zaman a\u015f\u0131m\u0131\")\n\n\tflag.Parse()\n\n\tfmt.Printf(\"Maksimum i\u015f\u00e7i say\u0131s\u0131: %d\\n\", *maxWorkers)\n\tfmt.Printf(\"Zaman a\u015f\u0131m\u0131 (saniye): %d\\n\", *timeoutSeconds)\n}\n<\/code><\/pre>\nKullan\u0131m: go run main.go --workers 8 --timeout 60<\/code><\/p>\nBoolean Bayraklar\u0131<\/h3>\n
Genellikle bir \u00f6zelli\u011fin a\u00e7\u0131l\u0131p kapanmas\u0131 gibi ikili durumlar i\u00e7in kullan\u0131l\u0131r (true<\/code>\/false<\/code>).<\/p>\n\nflag.Bool(name string, value bool, usage string) *bool<\/code><\/li>\nflag.BoolVar(p *bool, name string, value bool, usage string)<\/code><\/li>\n<\/ul>\nBoolean bayraklar \u00f6zel bir \u015fekilde i\u015flenir:<\/p>\n
\n--flagname<\/code> veya -flagname<\/code>: Varsay\u0131lan de\u011feri false<\/code> ise true<\/code> yapar.<\/li>\n--flagname=true<\/code> veya --flagname=false<\/code>: De\u011feri a\u00e7\u0131k\u00e7a belirtir.<\/li>\n--flagname true<\/code> (bo\u015fluklu): Bu kullan\u0131m flag<\/code> paketi i\u00e7in ge\u00e7erli de\u011fildir.<\/li>\n<\/ul>\npackage main\n\nimport (\n\t\"flag\"\n\t\"fmt\"\n)\n\nfunc main() {\n\tdebugMode := flag.Bool(\"debug\", false, \"Hata ay\u0131klama modunu etkinle\u015ftirir\")\n\tdryRun := flag.Bool(\"dry-run\", false, \"Ger\u00e7ek de\u011fi\u015fiklikler yapmadan i\u015flemi sim\u00fcle eder\")\n\n\tflag.Parse()\n\n\tif *debugMode {\n\t\tfmt.Println(\"Hata ay\u0131klama modu etkin.\")\n\t}\n\tif *dryRun {\n\t\tfmt.Println(\"Deneme \u00e7al\u0131\u015ft\u0131rmas\u0131 etkin. Ger\u00e7ek de\u011fi\u015fiklikler yap\u0131lmayacak.\")\n\t}\n}\n<\/code><\/pre>\nKullan\u0131m:<\/p>\n
\ngo run main.go --debug<\/code>: Hata ay\u0131klama modu etkin.<\/code><\/li>\ngo run main.go --debug=true --dry-run=false<\/code>: Hata ay\u0131klama modu etkin.<\/code><\/li>\ngo run main.go -dry-run<\/code>: Deneme \u00e7al\u0131\u015ft\u0131rmas\u0131 etkin. Ger\u00e7ek de\u011fi\u015fiklikler yap\u0131lmayacak.<\/code><\/li>\n<\/ul>\nS\u00fcre (Duration) Bayraklar\u0131<\/h3>\n
time.Duration<\/code> tipi i\u00e7in bayraklar tan\u0131mlaman\u0131za olanak tan\u0131r. S\u00fcre de\u011ferleri, “1s”, “10m”, “1h30m” gibi Go’nun time.ParseDuration<\/code> format\u0131nda belirtilir.<\/p>\n\nflag.Duration(name string, value time.Duration, usage string) *time.Duration<\/code><\/li>\nflag.DurationVar(p *time.Duration, name string, value time.Duration, usage string)<\/code><\/li>\n<\/ul>\npackage main\n\nimport (\n\t\"flag\"\n\t\"fmt\"\n\t\"time\"\n)\n\nfunc main() {\n\trefreshInterval := flag.Duration(\"interval\", 5*time.Second, \"Yenileme aral\u0131\u011f\u0131 (\u00f6rn: 1s, 30m, 2h)\")\n\t\n\tflag.Parse()\n\n\tfmt.Printf(\"Veriler her %s'de bir yenilenecek.\\n\", *refreshInterval)\n}\n<\/code><\/pre>\nKullan\u0131m: go run main.go --interval 1m30s<\/code> (1 dakika 30 saniye)<\/p>\n\u00d6zel Bayrak T\u00fcrleri (flag.Value<\/code> Aray\u00fcz\u00fc)<\/h3>\nflag<\/code> paketi, flag.Value<\/code> aray\u00fcz\u00fcn\u00fc uygulayarak kendi \u00f6zel bayrak t\u00fcrlerinizi tan\u0131mlaman\u0131za olanak tan\u0131r. Bu aray\u00fcz iki metot gerektirir:<\/p>\n\nSet(string) error<\/code>: Bir string de\u011feri alarak bayra\u011f\u0131n de\u011ferini ayarlar. Ayr\u0131\u015ft\u0131rma s\u0131ras\u0131nda kullan\u0131l\u0131r.<\/li>\nString() string<\/code>: Bayra\u011f\u0131n mevcut de\u011ferini string olarak d\u00f6nd\u00fcr\u00fcr. Varsay\u0131lan de\u011ferler ve kullan\u0131m mesajlar\u0131 i\u00e7in kullan\u0131l\u0131r.<\/li>\n<\/ul>\nBu, \u00f6zellikle virg\u00fclle ayr\u0131lm\u0131\u015f listeler, \u00f6zel yap\u0131land\u0131r\u0131lm\u0131\u015f stringler veya karma\u015f\u0131k veri yap\u0131lar\u0131n\u0131 do\u011frudan komut sat\u0131r\u0131ndan almak istedi\u011finizde \u00e7ok kullan\u0131\u015fl\u0131d\u0131r.<\/p>\n
\u00d6rnek: Virg\u00fclle ayr\u0131lm\u0131\u015f bir string listesini ayr\u0131\u015ft\u0131rmak i\u00e7in \u00f6zel bir bayrak:<\/p>\n
package main\n\nimport (\n\t\"flag\"\n\t\"fmt\"\n\t\"strings\"\n)\n\n\/\/ stringList, virg\u00fclle ayr\u0131lm\u0131\u015f stringlerin listesini tutar.\ntype stringList []string\n\n\/\/ String metodu, stringList'i string olarak temsil eder.\nfunc (s *stringList) String() string {\n\treturn strings.Join(*s, \",\")\n}\n\n\/\/ Set metodu, string de\u011feri al\u0131p listeye ekler.\nfunc (s *stringList) Set(value string) error {\n\t*s = strings.Split(value, \",\")\n\treturn nil\n}\n\nfunc main() {\n\tvar tags stringList\n\t\/\/ \u00d6zel bayra\u011f\u0131 tan\u0131mlamak i\u00e7in flag.Var() kullan\u0131l\u0131r.\n\tflag.Var(&tags, \"tags\", \"Virg\u00fclle ayr\u0131lm\u0131\u015f etiketler listesi\")\n\n\tvar userIDs stringList\n\tflag.Var(&userIDs, \"users\", \"Virg\u00fclle ayr\u0131lm\u0131\u015f kullan\u0131c\u0131 ID'leri\")\n\n\tflag.Parse()\n\n\tfmt.Printf(\"Etiketler: %v\\n\", tags)\n\tfmt.Printf(\"Kullan\u0131c\u0131 ID'leri: %v\\n\", userIDs)\n}\n<\/code><\/pre>\nKullan\u0131m: go run main.go --tags \"go,programming,cli\" --users \"101,205,330\"<\/code><\/p>\nBu \u00f6rnekte, stringList<\/code> tipi flag.Value<\/code> aray\u00fcz\u00fcn\u00fc uygulad\u0131\u011f\u0131 i\u00e7in, flag.Var()<\/code> fonksiyonu ile do\u011frudan bir bayrak olarak kullan\u0131labilir. Bu, flag<\/code> paketinin esnekli\u011fini g\u00f6steren g\u00fc\u00e7l\u00fc bir \u00f6zelliktir.<\/p>\nGeli\u015fmi\u015f Kullan\u0131m ve \u0130pu\u00e7lar\u0131<\/h2>\n
flag<\/code> paketi, temel kullan\u0131m\u0131n \u00f6tesinde, daha karma\u015f\u0131k senaryolar\u0131 y\u00f6netmek i\u00e7in de \u00f6zellikler sunar.<\/p>\nHata Y\u00f6netimi ve Kullan\u0131m Mesajlar\u0131<\/h3>\n
Yanl\u0131\u015f bir bayrak ad\u0131 veya ge\u00e7ersiz bir bayrak de\u011feri belirtildi\u011finde, flag<\/code> paketi varsay\u0131lan olarak bir hata mesaj\u0131 yazd\u0131r\u0131r ve programdan \u00e7\u0131kar. Bu davran\u0131\u015f genellikle istenen bir durum olsa da, bazen \u00f6zelle\u015ftirmek isteyebilirsiniz.<\/p>\nVarsay\u0131lan kullan\u0131m mesaj\u0131n\u0131 (usage message) \u00f6zelle\u015ftirmek i\u00e7in flag.Usage<\/code> de\u011fi\u015fkenine kendi fonksiyonunuzu atayabilirsiniz:<\/p>\npackage main\n\nimport (\n\t\"flag\"\n\t\"fmt\"\n\t\"os\"\n)\n\nfunc main() {\n\tname := flag.String(\"name\", \"Anonim\", \"Selam verilecek isim\")\n\tport := flag.Int(\"port\", 8080, \"Uygulaman\u0131n \u00e7al\u0131\u015faca\u011f\u0131 port numaras\u0131\")\n\n\t\/\/ flag.Usage'\u0131 \u00f6zelle\u015ftirme\n\tflag.Usage = func() {\n\t\tfmt.Fprintf(os.Stderr, \"Kullan\u0131m: %s [se\u00e7enekler] [arg\u00fcmanlar...]\\n\", os.Args[0])\n\t\tfmt.Fprintln(os.Stderr, \"Bu uygulama basit bir selamlay\u0131c\u0131d\u0131r.\")\n\t\tfmt.Fprintln(os.Stderr, \"Se\u00e7enekler:\")\n\t\tflag.PrintDefaults() \/\/ Tan\u0131mlanm\u0131\u015f t\u00fcm bayraklar\u0131n varsay\u0131lanlar\u0131n\u0131 yazd\u0131r\u0131r\n\t\tfmt.Fprintln(os.Stderr, \"\\n\u00d6rnek: myapp --name \\\"Ali\\\" --port 9000 file.txt\")\n\t}\n\n\tflag.Parse()\n\n\tfmt.Printf(\"Merhaba, %s! Uygulama %d portunda \u00e7al\u0131\u015f\u0131yor.\\n\", name, <\/em>port)\n\tif flag.NArg() > 0 {\n\t\tfmt.Printf(\"\u0130\u015flenecek dosyalar: %v\\n\", flag.Args())\n\t}\n}\n<\/code><\/pre>\n\u015eimdi go run main.go -h<\/code> veya ge\u00e7ersiz bir bayrak belirtildi\u011finde, kendi \u00f6zel kullan\u0131m mesaj\u0131n\u0131z g\u00f6sterilecektir.<\/p>\nAyr\u0131ca, flag<\/code> paketi hata durumunda programdan \u00e7\u0131kmak yerine bir hata d\u00f6nd\u00fcrmesi i\u00e7in flag.ExitOnError<\/code> yerine flag.ContinueOnError<\/code> veya flag.PanicOnError<\/code> se\u00e7eneklerini kullanabilirsiniz. Bu se\u00e7enekler flag.FlagSet<\/code> yap\u0131s\u0131n\u0131n bir par\u00e7as\u0131d\u0131r, ancak varsay\u0131lan flag.CommandLine<\/code> i\u00e7in de ayarlanabilir:<\/p>\npackage main\n\nimport (\n\t\"flag\"\n\t\"fmt\"\n\t\"os\"\n)\n\nfunc main() {\n\t\/\/ Hata durumunda programdan \u00e7\u0131kmak yerine hata d\u00f6nd\u00fcrmesini sa\u011flar\u0131z.\n\tflag.CommandLine.SetOutput(os.Stdout) \/\/ Hata mesajlar\u0131n\u0131 stdout'a y\u00f6nlendir\n\tflag.CommandLine.Usage = func() { \/\/ Hata durumunda da kullan\u0131m mesaj\u0131n\u0131 g\u00f6steririz\n\t\tfmt.Printf(\"Kullan\u0131m: %s [se\u00e7enekler]\\n\", os.Args[0])\n\t\tflag.PrintDefaults()\n\t}\n\tflag.CommandLine.Init(os.Args[0], flag.ContinueOnError)\n\n\tname := flag.String(\"name\", \"Anonim\", \"Selam verilecek isim\")\n\n\terr := flag.CommandLine.Parse(os.Args[1:]) \/\/ os.Args[1:] ile arg\u00fcmanlar\u0131 ayr\u0131\u015ft\u0131r\n\tif err != nil {\n\t\tfmt.Printf(\"Hata olu\u015ftu: %v\\n\", err)\n\t\treturn\n\t}\n\n\tfmt.Printf(\"Merhaba, %s!\\n\", *name)\n}\n<\/code><\/pre>\nBu \u00f6rnekte, flag.ContinueOnError<\/code> kullan\u0131ld\u0131\u011f\u0131nda, flag.CommandLine.Parse()<\/code> bir hata d\u00f6nd\u00fcrebilir ve program\u0131n hemen \u00e7\u0131kmas\u0131 engellenir. Bu, \u00f6zellikle karma\u015f\u0131k CLI uygulamalar\u0131nda hata i\u015fleme \u00fczerinde daha fazla kontrol sa\u011flamak i\u00e7in kullan\u0131\u015fl\u0131d\u0131r.<\/p>\nKalan Arg\u00fcmanlara Eri\u015fim (flag.Args()<\/code>)<\/h3>\nflag.Parse()<\/code> \u00e7a\u011fr\u0131ld\u0131ktan sonra, bayrak olarak tan\u0131mlanmayan ve ayr\u0131\u015ft\u0131r\u0131lmayan t\u00fcm komut sat\u0131r\u0131 arg\u00fcmanlar\u0131 flag.Args()<\/code> fonksiyonu arac\u0131l\u0131\u011f\u0131yla bir string dilimi olarak d\u00f6nd\u00fcr\u00fcl\u00fcr. flag.NArg()<\/code> ise kalan arg\u00fcmanlar\u0131n say\u0131s\u0131n\u0131 verir.<\/p>\npackage main\n\nimport (\n\t\"flag\"\n\t\"fmt\"\n)\n\nfunc main() {\n\tcount := flag.Int(\"count\", 1, \"Tekrar say\u0131s\u0131\")\n\t\n\tflag.Parse()\n\n\tfmt.Printf(\"Tekrar say\u0131s\u0131: %d\\n\", *count)\n\n\tif flag.NArg() > 0 {\n\t\tfmt.Printf(\"\u0130\u015flenecek \u00f6\u011feler: %v\\n\", flag.Args())\n\t} else {\n\t\tfmt.Println(\"\u0130\u015flenecek \u00f6\u011fe belirtilmedi.\")\n\t}\n}\n<\/code><\/pre>\nKullan\u0131m: go run main.go --count 5 item1 item2 item3<\/code><\/p>\n\u00c7\u0131kt\u0131: Tekrar say\u0131s\u0131: 5<\/code>, \u0130\u015flenecek \u00f6\u011feler: [item1 item2 item3]<\/code><\/p>\nflag.FlagSet<\/code> ile Bayrak Gruplar\u0131 Olu\u015fturma<\/h3>\nTek bir program i\u00e7inde birden fazla ba\u011f\u0131ms\u0131z bayrak grubuna ihtiyac\u0131n\u0131z oldu\u011funda, \u00f6rne\u011fin alt komutlar (subcommands) i\u00e7in (git commit<\/code>, go build<\/code> gibi), flag.FlagSet<\/code> yap\u0131s\u0131n\u0131 kullanabilirsiniz. Her FlagSet<\/code> kendi bayrak setini y\u00f6netir ve kendi Parse()<\/code> metoduna sahiptir.<\/p>\npackage main\n\nimport (\n\t\"flag\"\n\t\"fmt\"\n\t\"os\"\n)\n\nfunc main() {\n\t\/\/ Ana bayraklar\n\tverbose := flag.Bool(\"verbose\", false, \"Genel detayl\u0131 \u00e7\u0131kt\u0131\")\n\n\t\/\/ \"add\" alt komutu i\u00e7in FlagSet\n\taddCmd := flag.NewFlagSet(\"add\", flag.ExitOnError)\n\taddFile := addCmd.String(\"file\", \"\", \"Eklenecek dosya ad\u0131\")\n\taddForce := addCmd.Bool(\"force\", false, \"Ekleme i\u015flemini zorla\")\n\n\t\/\/ \"remove\" alt komutu i\u00e7in FlagSet\n\tremoveCmd := flag.NewFlagSet(\"remove\", flag.ExitOnError)\n\tremoveID := removeCmd.Int(\"id\", 0, \"Kald\u0131r\u0131lacak \u00f6\u011fenin ID'si\")\n\n\tflag.Parse() \/\/ Ana bayraklar\u0131 ayr\u0131\u015ft\u0131r\n\n\tif *verbose {\n\t\tfmt.Println(\"Genel detayl\u0131 mod etkin.\")\n\t}\n\n\t\/\/ Kalan arg\u00fcmanlara bakarak alt komutu belirle\n\tif flag.NArg() == 0 {\n\t\tfmt.Println(\"L\u00fctfen bir komut belirtin: add veya remove\")\n\t\tflag.Usage()\n\t\treturn\n\t}\n\n\tswitch flag.Args()[0] {\n\tcase \"add\":\n\t\taddCmd.Parse(flag.Args()[1:]) \/\/ \"add\" komutunun arg\u00fcmanlar\u0131n\u0131 ayr\u0131\u015ft\u0131r\n\t\tif *addFile == \"\" {\n\t\t\tfmt.Println(\"Hata: add komutu i\u00e7in --file belirtilmeli.\")\n\t\t\taddCmd.Usage()\n\t\t\tos.Exit(1)\n\t\t}\n\t\tfmt.Printf(\"Dosya ekleniyor: %s (Zorla: %t)\\n\", addFile, <\/em>addForce)\n\tcase \"remove\":\n\t\tremoveCmd.Parse(flag.Args()[1:]) \/\/ \"remove\" komutunun arg\u00fcmanlar\u0131n\u0131 ayr\u0131\u015ft\u0131r\n\t\tif *removeID == 0 {\n\t\t\tfmt.Println(\"Hata: remove komutu i\u00e7in --id belirtilmeli.\")\n\t\t\tremoveCmd.Usage()\n\t\t\tos.Exit(1)\n\t\t}\n\t\tfmt.Printf(\"\u00d6\u011fe kald\u0131r\u0131l\u0131yor: ID %d\\n\", *removeID)\n\tdefault:\n\t\tfmt.Printf(\"Bilinmeyen komut: %s\\n\", flag.Args()[0])\n\t\tflag.Usage()\n\t\tos.Exit(1)\n\t}\n}\n<\/code><\/pre>\nKullan\u0131m:<\/p>\n
\ngo run main.go add --file mydata.txt --force<\/code><\/li>\ngo run main.go remove --id 123<\/code><\/li>\ngo run main.go --verbose add --file newfile.txt<\/code><\/li>\n<\/ul>\nFlagSet<\/code> kullan\u0131m\u0131, karma\u015f\u0131k CLI uygulamalar\u0131n\u0131 daha mod\u00fcler ve y\u00f6netilebilir hale getirir.<\/p>\n\u00c7evre De\u011fi\u015fkenleri ile Entegrasyon<\/h3>\n
flag<\/code> paketi do\u011frudan \u00e7evre de\u011fi\u015fkenlerinden de\u011fer okuma \u00f6zelli\u011fi sunmaz. Ancak, bu i\u015flevselli\u011fi os.Getenv<\/code> kullanarak kolayca entegre edebilirsiniz:<\/p>\npackage main\n\nimport (\n\t\"flag\"\n\t\"fmt\"\n\t\"os\"\n\t\"strconv\"\n)\n\nfunc main() {\n\t\/\/ Varsay\u0131lan de\u011feri \u00e7evre de\u011fi\u015fkeninden al\n\tdefaultPort := 8080\n\tif envPort := os.Getenv(\"APP_PORT\"); envPort != \"\" {\n\t\tif p, err := strconv.Atoi(envPort); err == nil {\n\t\t\tdefaultPort = p\n\t\t}\n\t}\n\tport := flag.Int(\"port\", defaultPort, \"Uygulaman\u0131n \u00e7al\u0131\u015faca\u011f\u0131 port numaras\u0131 (APP_PORT \u00e7evre de\u011fi\u015fkeni ile de ayarlanabilir)\")\n\n\t\/\/ Varsay\u0131lan de\u011feri do\u011frudan \u00e7evre de\u011fi\u015fkeninden alan string bayrak\n\tdefaultAPIKey := os.Getenv(\"API_KEY\")\n\tapiKey := flag.String(\"api-key\", defaultAPIKey, \"API anahtar\u0131 (API_KEY \u00e7evre de\u011fi\u015fkeni ile de ayarlanabilir)\")\n\n\tflag.Parse()\n\n\tfmt.Printf(\"Uygulama %d portunda \u00e7al\u0131\u015f\u0131yor.\\n\", *port)\n\tif *apiKey != \"\" {\n\t\tfmt.Printf(\"API Anahtar\u0131: %s\\n\", *apiKey)\n\t} else {\n\t\tfmt.Println(\"API Anahtar\u0131 belirtilmedi.\")\n\t}\n}\n<\/code><\/pre>\nKullan\u0131m:<\/p>\n
\ngo run main.go<\/code>: Uygulama 8080 portunda \u00e7al\u0131\u015f\u0131yor. API Anahtar\u0131 belirtilmedi.<\/code><\/li>\nAPP_PORT=9000 API_KEY=mysecretkey go run main.go<\/code>: Uygulama 9000 portunda \u00e7al\u0131\u015f\u0131yor. API Anahtar\u0131: mysecretkey<\/code><\/li>\nAPP_PORT=9000 go run main.go --port 9090<\/code>: Komut sat\u0131r\u0131 arg\u00fcmanlar\u0131 her zaman \u00e7evre de\u011fi\u015fkenlerini ezer. Bu durumda port 9090 olur.<\/li>\n<\/ul>\nVarsay\u0131lan De\u011ferleri De\u011fi\u015ftirme<\/h3>\n
Bayraklar\u0131 tan\u0131mlarken bir varsay\u0131lan de\u011fer atars\u0131n\u0131z. Ancak bazen programatik olarak bir bayra\u011f\u0131n varsay\u0131lan de\u011ferini de\u011fi\u015ftirmek isteyebilirsiniz. Bunu flag.Lookup()<\/code> ve flag.Value.Set()<\/code> metodlar\u0131n\u0131 kullanarak yapabilirsiniz:<\/p>\npackage main\n\nimport (\n\t\"flag\"\n\t\"fmt\"\n)\n\nfunc main() {\n\tname := flag.String(\"name\", \"Varsay\u0131lan\", \"Selam verilecek isim\")\n\n\t\/\/ Programatik olarak varsay\u0131lan de\u011feri de\u011fi\u015ftirme\n\tif f := flag.Lookup(\"name\"); f != nil {\n\t\tf.Value.Set(\"YeniVarsay\u0131lan\") \/\/ Set metodu string bekler\n\t}\n\n\tflag.Parse()\n\n\tfmt.Printf(\"Merhaba, %s!\\n\", *name)\n}\n<\/code><\/pre>\nBu \u00f6rnekte, e\u011fer komut sat\u0131r\u0131nda --name<\/code> belirtilmezse, yeni varsay\u0131lan de\u011fer olan “YeniVarsay\u0131lan” kullan\u0131lacakt\u0131r.<\/p>\nUygulama \u00d6rne\u011fi: Basit Bir Komut Sat\u0131r\u0131 Arac\u0131<\/h2>\n
\u015eimdiye kadar \u00f6\u011frendiklerimizi bir araya getirerek, basit bir metin dosyas\u0131 i\u015fleme arac\u0131 olu\u015ftural\u0131m. Bu ara\u00e7, bir giri\u015f dosyas\u0131n\u0131 okuyacak, iste\u011fe ba\u011fl\u0131 olarak b\u00fcy\u00fck harfe \u00e7evirecek ve \u00e7\u0131kt\u0131 dosyas\u0131n\u0131 belirleyecek.<\/p>\n
package main\n\nimport (\n\t\"bufio\"\n\t\"flag\"\n\t\"fmt\"\n\t\"io\"\n\t\"os\"\n\t\"strings\"\n)\n\nfunc main() {\n\t\/\/ Bayraklar\u0131 tan\u0131mlama\n\tinputFilePath := flag.String(\"input\", \"\", \"Giri\u015f metin dosyas\u0131n\u0131n yolu (zorunlu)\")\n\toutputFilePath := flag.String(\"output\", \"\", \"\u00c7\u0131kt\u0131 metin dosyas\u0131n\u0131n yolu (varsay\u0131lan: stdout)\")\n\tuppercase := flag.Bool(\"uppercase\", false, \"\u00c7\u0131kt\u0131y\u0131 b\u00fcy\u00fck harfe \u00e7evir\")\n\tlinePrefix := flag.String(\"prefix\", \"\", \"Her sat\u0131r\u0131n ba\u015f\u0131na eklenecek \u00f6n ek\")\n\n\t\/\/ Kullan\u0131m mesaj\u0131n\u0131 \u00f6zelle\u015ftirme\n\tflag.Usage = func() {\n\t\tfmt.Fprintf(os.Stderr, \"Kullan\u0131m: %s [se\u00e7enekler]\\n\", os.Args[0])\n\t\tfmt.Fprintln(os.Stderr, \"Basit bir metin dosyas\u0131 i\u015fleme arac\u0131.\")\n\t\tfmt.Fprintln(os.Stderr, \"Se\u00e7enekler:\")\n\t\tflag.PrintDefaults()\n\t\tfmt.Fprintln(os.Stderr, \"\\n\u00d6rnek: mytexttool --input data.txt --output processed.txt --uppercase\")\n\t}\n\n\tflag.Parse()\n\n\t\/\/ Giri\u015f dosyas\u0131 zorunlu\n\tif *inputFilePath == \"\" {\n\t\tfmt.Fprintln(os.Stderr, \"Hata: --input bayra\u011f\u0131 zorunludur.\")\n\t\tflag.Usage()\n\t\tos.Exit(1)\n\t}\n\n\t\/\/ Giri\u015f dosyas\u0131n\u0131 a\u00e7\n\tinputFile, err := os.Open(*inputFilePath)\n\tif err != nil {\n\t\tfmt.Fprintf(os.Stderr, \"Giri\u015f dosyas\u0131 a\u00e7\u0131lamad\u0131: %v\\n\", err)\n\t\tos.Exit(1)\n\t}\n\tdefer inputFile.Close()\n\n\t\/\/ \u00c7\u0131kt\u0131 hedefini belirle (dosya veya stdout)\n\tvar outputWriter io.Writer\n\tif *outputFilePath != \"\" {\n\t\toutputFile, err := os.Create(*outputFilePath)\n\t\tif err != nil {\n\t\t\tfmt.Fprintf(os.Stderr, \"\u00c7\u0131kt\u0131 dosyas\u0131 olu\u015fturulamad\u0131: %v\\n\", err)\n\t\t\tos.Exit(1)\n\t\t}\n\t\tdefer outputFile.Close()\n\t\toutputWriter = outputFile\n\t} else {\n\t\toutputWriter = os.Stdout\n\t}\n\n\tscanner := bufio.NewScanner(inputFile)\n\twriter := bufio.NewWriter(outputWriter)\n\tdefer writer.Flush() \/\/ \u00c7\u0131k\u0131\u015ftan \u00f6nce t\u00fcm tamponu bo\u015falt\n\n\tlineNum := 0\n\tfor scanner.Scan() {\n\t\tlineNum++\n\t\tline := scanner.Text()\n\n\t\t\/\/ \u00d6n ek ekle\n\t\tif *linePrefix != \"\" {\n\t\t\tline = *linePrefix + line\n\t\t}\n\n\t\t\/\/ B\u00fcy\u00fck harfe \u00e7evir\n\t\tif *uppercase {\n\t\t\tline = strings.ToUpper(line)\n\t\t}\n\n\t\t\/\/ \u00c7\u0131kt\u0131ya yaz\n\t\t_, err := writer.WriteString(line + \"\\n\")\n\t\tif err != nil {\n\t\t\tfmt.Fprintf(os.Stderr, \"\u00c7\u0131kt\u0131ya yazarken hata olu\u015ftu: %v\\n\", err)\n\t\t\tos.Exit(1)\n\t\t}\n\t}\n\n\tif err := scanner.Err(); err != nil {\n\t\tfmt.Fprintf(os.Stderr, \"Giri\u015f dosyas\u0131n\u0131 okurken hata olu\u015ftu: %v\\n\", err)\n\t\tos.Exit(1)\n\t}\n\n\tfmt.Printf(\"\u0130\u015flem tamamland\u0131. %d sat\u0131r i\u015flendi.\\n\", lineNum)\n}\n<\/code><\/pre>\nBu arac\u0131 kullanmak i\u00e7in \u00f6nce bir data.txt<\/code> dosyas\u0131 olu\u015ftural\u0131m:<\/p>\n