TRANSLATE is a thin abstraction layer over the ordinary strings
which allows the creation of a seamless translation for your
project. The code is written in a plain Common Lisp without any
dependencies. A system definition is provided in ASD format,
although ASDF isn’t required to run this software.
This library is licensed under LLGPLv2, which means that it may be
used in any project for any purpose although any significant
modifications to the library should be published. It doesn’t impose
it’s license on software depending on it.
To illustrate library usage some imaginary functions are used:
MAKE-BUTTON and MAKE-LABEL. The following sample code convention
is used:
- lines preceded with ==> indicate reader input
- all other lines represent printer output
The library pollutes *READTABLE* with dispatch macro character
#t, where “t” is abbreviation of “translate”. Instead of writing
ordinary constant strings in his/her application, the user instead
precedes them with #t:
==> #t"dum dum dum, piję rum"
"la la la, I drink in the spa"If TRANSLATE:*LANGUAGE* is bound to NIL and
TRANSLATE:*RESOLUTION-TIME* to :LOAD-TIME, then #t“hello”
will resolve to the string “hello” and the translation will have no
effect. It is convenient, because programmer can put #t“strings”
for the future translation with no functional consequences at
run-time while keeping application innards visually separated from
the messages meant to be presented to user.
==> (setf translate:*language* nil)
NIL
==> (make-button :label #t"hello")
#<button "hello">Binding TRANSLATE:*LANGUAGE* to a non-NIL value enables string
translation. If no translation exists it will be temporarily
translated to the same value enclosed in a curly brackets:
==> (translate:define-language :pl)
(#<hash-table 00000000054323c0> NIL #<compiled-function 0000000005fe08c0>)
==> (setf translate:*language* :pl)
:PL
==> (make-label :text #t"Greetings, programs")
;;; Warning: phrase "Greetings, programs" isn't defined for language :PL.
#<label "{Greetings, programs}">
==> (make-label :text #t"Leave the grid")
;;; Warning: phrase "Leave the grid" isn't defined for language :PL.
#<label "{Leave the grid}">Using a string that has not been translated will cause a warning at
resolution time and string will be added to the special list of
phrases not yet translated (which may be evaluated for future
processing, like adding the missing translations). If a language
put in the TRANSLATE:*LANGUAGE* isn’t defined yet, CERROR will
be signaled with a restart allowing language creation.
To distinguish dictionaries, the predicate EQL is used and
phrases are distinguished using the predicate EQUAL, so the most
convenient is using symbols as the language designators. It also
implies, that phrases meant for translation are case sensitive.
To add translations, two interfaces are provided. The
ADD-SINGLE-TRANSLATION function takes three arguments, where the
first is the language for which we provide translation, the second
is a translated phrase and the third is an actual
translation. Phrase type must be a string, but the translation
might be any kind of object (although it is advised to use strings,
the user is free to shoot himself in the foot by abusing the
translation mechanism).
==> (translate:add-single-translation 'pl "hello" "Witaj!")
;;; Warning: Implicitly creating language PL.
[PL] hello -> Witaj!
"Witaj!"
==> (translate:add-single-translation 'en "hello" "Welcome!")
;;; Warning: Implicitly creating language EN.
[EN] hello -> Welcome!
"Welcome!"
==> (translate:add-single-translation
'pl "bang"
(let ((i 1))
(lambda ()
(format nil "bah ~A" (incf i)))))
bang -> #<bytecompiled-closure #<bytecompiled-function 00000000067d9f50>> (PL)
#<bytecompiled-closure #<bytecompiled-function 00000000067d9f50>>ADD-TRANSLATIONS is a simple wrapper around
ADD-SINGLE-TRANSLATION that allows the translation of multiple
phrases in one form. The first argument is once again the
translation language, while all further arguments are alternately
phrases and translations.
==> (translate:add-translations 'pl
"header-about" "O firmie"
"header-offer" "Oferta"
"header-blog" "Blog"
"header-pricing" "Cennik"
"header-contact" "Kontakt")
[PL] header-about -> O firmie
[PL] header-offer -> Oferta
[PL] header-blog -> Blog
[PL] header-pricing -> Cennik
[PL] header-contact -> Kontakt
T
==> (translate:add-translations 'en
"header-about" "About"
"header-offer" "Offer"
"header-blog" "Blog"
"header-pricing" "Prices"
"header-contact" "Contact")
[EN] header-about -> About
[EN] header-offer -> Offer
[EN] header-blog -> Blog
[EN] header-pricing -> Prices
[EN] header-contact -> Contact
TGenerally it is advised to use symbolic and meaningful names for phrases to be translated, not the final phrases written in English. Providing “translation-tags” of concise form is easier to comprehend for people who will translate the application.
Loading the code is enough to catch all not yet translated phrases
for the active language (bound to TRANSLATE:*LANGUAGE*) if
resolution is performed at load time. Otherwise, an untranslated
phrase is saved after it’s first evaluation. To list saved phrases
without translations, the function MISSING-TRANSLATIONS is
available. It returns a list of the form {((LANG (PHRASES*))*)}.
==> (translate:missing-translations)
((PL ("phrase-1" "phrase-2" "phrase-3"))
(BG ("phrase-1" "phrase-3")))Such output means, that language PL doesn’t have translations for
“phrase-1”, “phrase-2” and “phrase-3”, while BG doesn’t have
translations for “phrase-1” and “phrase-3”. Languages which have
all translations are filtered and they don’t appear in the result.
The library may work in two different modes which dictate the time when the actual translation is performed. Strings may be translated at load-time, or at run-time.
The first approach is faster, because it doesn’t require any
processing at run-time, while the second is much more flexible
allowing the change of dictionaries and translations when the
program is running or depending on lexically scoped value of the
parameter TRANSLATE:*LANGUAGE*.
It is important to remember that, when translations are done at
run-time, strings preceded by #t are transformed to the function
calls and they may work not as expected in the context where
enclosing macro prevents their evaluation.
==> (setf translate:*resolution-time* :run-time)
:RUN-TIME
==> (setf translate:*language* :en)
:EN
==> (translate:add-single-translation :en "hello" "Hello")
[EN] hello -> Hello
==> (translate:add-single-translation :pl "hello" "Cześć")
[PL] hello -> Cześć
==> (let ((translate:*language* :en))
#t"hello")
"Hello"
==> (let ((translate:*language* :pl))
#t"hello")
"Cześć"
==> (quote #t"hello")
(TRANSLATE:TRANSLATE "hello")When translation is performed at load-time, the translation has to
be present before the actual phrase is used (e.g. in a lambda
expression), because phrases are resolved to their translations
immediately. That also means that changing TRANSLATE:*LANGUAGE*
in the future won’t affect translations resolved earlier.
==> (setf translate:*resolution-time* :load-time)
:LOAD-TIME
==> (setf translate:*language* :en)
:EN
==> (defparameter *my-function-1*
(lambda () #t"hello"))
;;; Warning: phrase "hello" isn't defined for language EN.
*MY-FUNCTION-1*
==> (translate:add-single-translation :en "hello" "Hello")
hello -> Hello (EN)
==> (translate:add-single-translation :pl "hello" "Cześć")
hello -> Cześć (PL)
==> (let ((*language* :en))
#t"hello")
"Hello"
==> (let ((*language* :pl)) ; lexical scope is ignored
#t"hello")
"Hello"
==> (defparameter *my-function-2*
(lambda () #t"hello"))
*MY-FUNCTION-2*
==> (funcall *my-function-1*) ; phrase wasn't translated when function was created
"{hello}"
==> (funcall *my-function-2*)
"Hello"
==> (quote #t"hello")
"Hello"Translation at run-time is better when the programmer wants to add
translations ad-hoc or wants to switch languages when the
application is running. Load-time translation is more suitable for
static translations for deployed applications or where macros
prevent necessary evaluation of the expressions. Also when the
programmer wants to add translations in future (if language is
bound to nil and resolution is performed at load-time the
expression #t“hello world” means the same as the “hello world”).
This variable holds the current language designator (the predicate
used for comparison is EQL). If bound to NIL, translation works the
same way as the IDENTITY function.
Applicable values are :LOAD-TIME and :RUN-TIME (the latter is the
default). The variable controls time of actual resolution.
If it's the :LOAD-TIME, then resolution is performed when the reader
encounters the #t dispatch macro character, while setting the variable
to :RUN-TIME translates #t"string" to the form (TRANSLATE "string")
and resolution takes place at the time of the form evaluation.
DEFINE-LANGUAGE - external symbol in TRANSLATE package
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DEFINE-LANGUAGE (NAME &REST TRANSLATIONS) [Function]
Define language NAME with provided TRANSLATIONS
If LANGUAGE exists, a continuable error is signalled, which allows either
dropping the operation or superseding the language which is already defined.
TRANSLATIONS are alternating phrases and their corresponding objects.
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ADD-SINGLE-TRANSLATION - external symbol in TRANSLATE package
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ADD-SINGLE-TRANSLATION (LANGUAGE PHRASE TRANSLATION) [Function]
Add TRANSLATION of PHRASE for given LANGUAGE
If LANGUAGE doesn't exist, it is implicitly created and a warning is
emmited.
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ADD-TRANSLATIONS - external symbol in TRANSLATE package
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ADD-TRANSLATIONS (LANGUAGE &REST TRANSLATIONS) [Function]
Add any number of TRANSLATIONS for the given LANGUAGE
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TRANSLATE - external symbol in TRANSLATE package
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TRANSLATE (PHRASE &OPTIONAL (LANGUAGE *LANGUAGE*)) [Function]
Find the translation of PHRASE in the store associated with LANGUAGE
If LANGUAGE is NIL, then this is the same as the IDENTITY function. If
the provided LANGUAGE isn't defined, the store is explicitly
created. If no PHRASE is defined for a given language, it is stored
for later translation and replaced by PHRASE surrunded by curly
brackets.
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MISSING-TRANSLATIONS - external symbol in TRANSLATE package
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MISSING-TRANSLATIONS [Function]
Creates a list of phrases which aren't translated for the defined
languages. Returns a list of form: ({(LANG ({PHRASE}*))}*)
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