From: Vicente BOTET <vicente.botet@wanadoo.fr>
Message du 16/04/11 15:01 De : "Artyom"
I have made a diagonal reading and I find your library really interesting.
I
think I will spent quite more time reviewing it.
I have just a first minimal and formal remark. When I see the overloading of
the translate function
message boost::locale::translate (char const *msg) message boost::locale::translate (char const *context, char const *msg) message boost::locale::translate (char const *single, char const *plural, int
n) message boost::locale::translate (char const *context, char const *single,
char const *plural, int n) message boost::locale::translate (std::string const &msg) message boost::locale::translate (std::string const &context, std::string
const &msg) message boost::locale::translate (std::string const &context, std::string
const &single, std::string const &plural, int n) message boost::locale::translate (std::string const &single, std::string const
&plural, int n)
this let me think that it would be difficult to know know what is the message, the context, the domain, whether the message is the singular or plural form.
This is the general concept of how gettext used around. So I stick with its
conversion extending it, same concept used in Qt. It is quite common.
I agree that it is not perfect but it seems to be ok.
I'm sure that you will reach to provide something clearer that don't adhere to gettext (which is hidden for the user).
It is not really hidden user expected to use: gettext catalogs, gettext tools like msgfmt or xgettext, and use localization programs that support gettext like Lokalize or poedit. Also gettext fine but it has three major drawbacks that are solved by Boost.Locale - Support of multiple locales in same process - More permissive runtime (BSL vs LGPL) - Support of wide characters (wgettext)
The equivalent for (w)gettext uses the c-like idiom, i.e. uses different names.
std::string boost::locale::gettext (char const *id, std::locale const &loc=std::locale()) std::string boost::locale::ngettext (char const *s, char const *p, int n,
std::locale const &loc=std::locale()) std::string boost::locale::dgettext (char const *domain, char const *id, std::locale const &loc=std::locale()) std::string boost::locale::dngettext (char const *domain, char const *s, char
const *p, int n, std::locale const &loc=std::locale()) std::string boost::locale::pgettext (char const *context, char const *id,
std::locale const &loc=std::locale()) std::string boost::locale::npgettext (char const *context, char const *s, char
const *p, int n, std::locale const &loc=std::locale()) std::string boost::locale::dpgettext (char const *domain, char const *context,
char const *id, std::locale const &loc=std::locale()) std::string boost::locale::dnpgettext (char const *domain, char const *context, char const *s, char const *p, int n, std::locale const &loc=std::locale())
Neither is satisfying me.
These are mostly gettext compatibility functions so users familiar with gettext would find themselves with (almost) same API.
You are not forced to provide C-like interfaces in a Boost library to content some users that know the gettext interface. It is quite ugly.
translate and gettext have little bit different meaning. translate creates an object that is convertable to localized message according to targets's (stream) locale while gettext takes locale as parameter out << translate("Hello"); May be different from out << gettext("Hello"); As translate would use out's locale while gettext would use global locale. Also I do not see something wrong with gettext basic interface. Most users who ever used gettext are familiar with it.
I was wondering if the use of Boost.Parameters could help.
I'm not really familiar with Boost.Parameters but from quick glance it requires not-so trivial template metaprogramming but what is even more important I'm afraid that things like
translate(context_ = "File","Open")
I had no issue explaining this idiom to users of a library. Another question is for the implementer of the library, some more explanation will be needed.
May scary off some average C++ programmers that would not understand what is this thing
context_ = "File"
Finally I want Boost.Locale be used by not brilliant C++ programmers as well.
I know what hard times I have explaining about boost::bind to average C++ programmers so making things like that would not help too much.
Well, it is your library. It is up to you to maintain ugly interfaces like the preceding ones. From my side the add a -1 to the review. Fortunately there are a lot of positive parts.
I really like translate(context("File"),"Open") over the first. It is much clearer from user point of view.
could be written as
cout << format(translate("You have 1 file in the directory", plural("You have {1} files in the directory"),files)) % files << endl;
button->setLabel(translate(context("File"),"open"));
With this modification, the (w)gettext could all share the same names and
there will be no need to use c-like names.
What you think?
This one more interesting. However there an important point to check:
Integration with xgettext - would it be able to read this or entire new xgettext should be developed to extract strings.
I don't understand. Could you clarify, please? For me all the gettext functions should share the same name as well as all all the wgettext. No need to use the prefixed 'p' 'd' ...
I explain. Boost.Locale does not live alone. It requires other tools, for example nice programs like poedit or Lokalize to translate the messages. You should also use gettext binary tools: - xgettext - extracts the strings from sources and creates pot files useable for translators - msgfmt - convert po files to mo files - msgmerge - merge translated files with updated strings And much more. See: http://cppcms.sourceforge.net/boost_locale/html/messages_formatting.html#ext... Now xgettext tools know to handle C++ overloading well but I'm not sure if it would handle tranlsate(convert("File"),"Open"). When it handles translate("File","Open") well. So likely that means that boost_xgettext tool should be written (and this isn't that simple). So I'm not sure that users would be happy to work with two tools boost_xgettext and xgettext to extract messages from the files especially when the project uses gettext in may parts (including non-C++ ones) In any case I'll check this.
I need to think about, probably it may be an alternative.
You could also associate the translate function to the context object
button->setLabel(context("File").translate("open"));
This can be extended to the domain,
button->setLabel(domain("D").context("File").translate("open"));
but doesn't scale well for the plural parameter.
This way or other all these are attempts to overcome the limitation of C++ to have named parameters... Maybe it is something that should be solved at language level. I don't know. But in C++ we usually live without named parameters... It is a point to think about. And I don't currently have fast and simple solution. Best, Artyom