I18nize Scala programs à la gettext
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This document discusses internationalizing (i18n) Scala programs using the gettext approach. It describes marking strings for translation, extracting them to template files, loading translation files, and translating at runtime. Tools are introduced for extracting strings from Scala code and templates, editing translation files, and parsing loaded files. The approach works for various Scala template engines and frameworks like Play.
![fr.po language file:
msgid ""
msgstr "Plural-Forms: nplurals=2; plural=n>1;"
msgid "I have one apple"
msgid_plural "I have %d apples"
msgstr[0] "J'ai une pomme"
msgstr[1] "J'ai %d pommes"
Singular/plural rule
Special key](https://image.slidesharecdn.com/i18nalagettext-150811205648-lva1-app6891/85/I18nize-Scala-programs-a-la-gettext-22-320.jpg)
I18nize Scala programs à la gettext
- 1. i18nize Scala programs à la gettext Episode 39, Wed, Aug 12, 2015 Ngoc Dao
- 2. About the speaker ● Ngoc Dao ● Joined Atlassian since May
- 3. ● Favorite languages: Ruby, Erlang, Scala
- 4. ● Favorite languages: Ruby, Erlang, Scala ● My Scala style: Using Scala as if Scala = Java (performance, libs eco) + Ruby (human oriented) + Erlang (functional)
- 5. ● Don’t know Scalaz/Haskell (yet) ↑↑↑ Struggling with monadic talks at ScalaSyd
- 6. English is not my native language ● From Viet Nam ● 15 years in Japan ↑↑↑ i18n is important to me
- 7. Given this program: printf("My name is %s.", myName)
- 8. Given this program: printf("My name is %s.", myName) Let’s i18nize it in gettext style! (I won’t go into details of .properties style vs gettext style)
- 9. (1) Mark the strings we want to translate printf(t("My name is %s."), myName)
- 10. i18n.pot template file: msgid "My name is %s." msgstr "" (2) Extract to a template file (1) Mark the strings we want to translate printf(t("My name is %s."), myName)
- 11. i18n.pot template file: msgid "My name is %s." msgstr "" fr.po language file: msgid "My name is %s." msgstr "Je m'appelle %s." (2) Extract to a template file (3) Give it to translators (1) Mark the strings we want to translate printf(t("My name is %s."), myName)
- 12. When strings in the program change, how to update (add, remove, modify) language files efficiently?
- 13. When strings in the program change, how to update (add, remove, modify) language files efficiently? ● Automatically copy similar existing translation to make new translation (marked as “fuzzy” to be modified by a human later)
- 14. When strings in the program change, how to update (add, remove, modify) language files efficiently? ● Automatically copy similar existing translation to make new translation (marked as “fuzzy” to be modified by a human later) ● Don’t delete, just comment out dated translations for future references
- 15. When strings in the program change, how to update (add, remove, modify) language files efficiently? ● Automatically copy similar existing translation to make new translation (marked as “fuzzy” to be modified by a human later) ● Don’t delete, just comment out dated translations for future references ● In translation files, sort by msgid so that it’s easier to diff versions
- 16. fr.po language file: msgid "My name is %s." msgstr "Je m'appelle %s." ja.po language file: msgid "My name is %s." msgstr "%sと申します。" (4) Load language files to program, basically parse the files to key → value data structure vi.po language file: msgid "My name is %s." msgstr "Tôi tên là %s."
- 17. printf(t("My name is %s."), myName) printf("Je m’appelle %s.", myName) (5) At run time, the marker acts as a function to replace the given key with its value
- 18. gettext is quite advanced ● Allow specifying context (one string may be translated to different strings, depending on context)
- 19. print(t("Hello")) print(tc("Casual", "Hello")) fr.po language file: msgid "Hello" msgstr "Bonjour" msgctxt "Casual" msgid "Hello" msgstr "Salut"
- 20. gettext is quite advanced ● Allow specifying singular/plural rules (different languages may have different singular/plural rules)
- 21. print(tn( "I have one apple", "I have %d apples", numApples )) Singular Plural Depending on this value
- 22. fr.po language file: msgid "" msgstr "Plural-Forms: nplurals=2; plural=n>1;" msgid "I have one apple" msgid_plural "I have %d apples" msgstr[0] "J'ai une pomme" msgstr[1] "J'ai %d pommes" Singular/plural rule Special key
- 23. Demo I’ll introduce some tools
- 25. Mark and extract i18n strings
- 26. Mark and extract i18n strings Tool: https://github.com/xitrum-framework/scala-xgettext It’s a Scala compiler plugin, to extract i18n strings at compile time.
- 27. Mark and extract i18n strings Tool: https://github.com/xitrum-framework/scala-xgettext It’s a Scala compiler plugin, to extract i18n strings at compile time. ↑↑↑ Neat! Just compile Scala source code and get the strings. Scala is powerful
- 28. ● scala-xgettext can also extracts i18n strings from view templates ● as long as the templates are converted to Scala source code and compiled Mark and extract i18n strings
- 29. ● scala-xgettext can also extracts i18n strings from view templates ● as long as the templates are converted to Scala source code and compiled ↑↑↑ It works for all popular Scala template engines like Scalate, Scalatags, Twirl (Play framework template engine) Mark and extract i18n strings
- 30. Translate language template file
- 31. Translate language template file Tool: Any text editor
- 32. Translate language template file Tool: Any text editor Very convenient GUI editor: https://poedit.net/
- 33. Load language file Tool: https://github.com/xitrum-framework/scaposer It’s a Scala parser to transform .po text file into key → value data structure
- 34. Poedit demo: Update i18n strings ● Add, modify, remove i18n strings in program ● Regenerate i18n.pot file ● Use Poedit to update existing .po files with the new i18n.pot file ● Poedit can give translation hints for similar strings
- 35. Demo source code: https://github.com/xitrum-framework/scala-xgettext-presentation If you use Play framework: https://github.com/georgeOsdDev/play-xgettext