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Hello, Verden!
Go Cph
2 May 2018
Go internationalization and localization
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Hej!Mit navn er Terin.
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Localization is the
act of adapting to
meet local
expectations
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Internationalization
is the design and
implementation
that enables
localization
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gettext(3)
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printf(ngettext(
"%s has one car.\n",
"%s has %d cars.\n",
num_cars
),
name,
num_cars
);
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Strings are extracted from the program's source into a Portable
Object Template.
xgettext -c main.c -o main.pot
This results in main.pot.
#: main.c:1
msgid "%s has one car.\n"
msgid_plural "%s has %d cars.\n"
msgstr[0] ""
msgstr[1] ""
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A translator can generate a Portable Object file.
msginit --locale=da --input=main.pot
Then translate da.po.
#: main.c:1
msgid "%s has one car.\n"
msgid_plural "%s has %d cars.\n"
msgstr[0] "%s har en bil.\n"
msgstr[1] "%s har %d biler.\n"
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During the build step, Portable Object files are compiled into Machine
Object files, and distributed with the software package.
At runtime, the appropriate locale is displayed based on the setting of
environment variables.
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golang.org/x/text
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Formatted Output
import "golang.org/x/text/message"
p := message.NewPrinter(language.Danish)
p.Printf(
"Hello, my name is %s. I have %d cars.\n",
name,
num_cars,
)
"Hello, my name is Terin. I have 1.024 cars.\n"
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Formatted Numerics
import "golang.org/x/text/number"
p.Printf("I have %v bytes.\n", number.Decimal(1024))
Formats this via the printer's locale:
I have 1.024 bytes.
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Formatted Numerics
p.Printf(
"The mass of the sun is %v kilograms.\n",
number.Scientific(1.9891e30))
Formats this via the printer's locale:
The mass of the sun is 2 × 10³⁰ kilograms.
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Formatted Numerics
p.Printf(
"The maximum power output is %v watts.\n",
number.Engineering(2e7))
Formats this via the printer's locale:
The maximum power output is 20 × 10⁶ watts.
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Formatted Currencies
import "golang.org/x/text/currency"
amount := currency.DKK.Amount(1234.56)
p.Printf("Total: %v\n", currency.Symbol(amount))
Formats this via the printer's locale:
Total: kr. 1234.56
☹
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Collations
import "golang.org/x/text/collate"
c := collate.New(language.Danish)
strings := StringSlice{
[]string{"åben", "adelig"},
}
c.Sort(strings)
// ["adelig", "åben"]
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Locales
● Composed of multiple parts, to
define language, script, region,
variants, and extensions.
● Go uses BCP 47 language tags
○ en
○ en-DK
○ da
○ da-GL
○ zh-Hans
○ he-IL-u-ca-hebrew-tz-jeruslm
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Locales
import "golang.org/x/text/language"
var l language.Tag
l = language.English
l = language.MustParse("he-IL-u-ca-hebrew-tz-jeruslm")
p := message.NewPrinter(l)
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HTTP Handler
import "golang.org/x/text/language"
matcher := language.NewMatcher([]language.Tag{
language.English,
language.MustParse("en-AU"),
language.Danish,
language.Chinese,
})
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HTTP Handler
handler(w http.ResponseWriter, r *http.Request) {
lang, _ := r.Cookie("lang")
accept := r.Header.Get("Accept-Language")
tag, _ := language.MatchStrings(
matcher, lang.String(), accept)
p := message.NewPrinter(tag)
p.Fprintln(w, "Hello World")
}
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CLI Application
tag, err := language.Parse(os.Getenv("LANG"))
if err != nil {
tag = language.English
}
p := message.NewPrinter(tag)
p.Printf(w, "Hello World")
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Defining
Translations
Go defines translations in
"catalogs" that are transparently
used when formatting strings using
the message printer.
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Building a Catalog
import "golang.org/x/text/message/catalog"
l := language.Danish
cat := catalog.NewBuilder()
cat.SetString(l,
"Hello, my name is %s.\n",
"Hej, mit navn er %s.\n",
)
p := message.NewPrinter(l, message.Catalog(cat))
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Plurals
import "golang.org/x/text/feature/plural"
cat.Set(
language.Danish,
"I have %d cars.\n",
plural.Selectf(1, "%d",
"=0", "Jeg har ingen biler.\n",
"one", "Jeg har en bil.\n",
"other", "Jeg har %d biler.\n",
),
)
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Catalog Interface
type Catalog interface {
Languages() []language.Tag
Matcher() language.Matcher
Context(tag language.Tag, r catmsg.Renderer) *Context
}
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gotext
go get golang.org/x/text/cmd/gotext/...
● Go replacement for "gettext"
○ Extract text from Go programs
○ Update catalogs
○ Code generation for loading catalogs
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Future Work ● Gender support
● Date formatting
● Much more!