Re: [boost] Boost.Locale and the standard "message" facet

Subject: Re: [boost] Boost.Locale and the standard "message" facet
From: Vicente BOTET (vicente.botet_at_[hidden])
Date: 2011-05-02 08:54:32

> Message du 02/05/11 11:28
> De : "Artyom" 
> A : boost_at_[hidden]
> Copie à : 
> Objet : Re: [boost] Boost.Locale and the standard "message" facet
> 
> > From: Vicente BOTET 
> > 
> > Hi,
> > 
> > > Message du 30/04/11 15:48
> > > De : "Artyom" 
> > > A : boost_at_[hidden]
> > > Copie à : 
> > > Objet : Re: [boost] Boost.Locale and the standard "message" facet
> > > 
> > > > Subject: [boost] Boost.Locale and the standard "message" facet
> > > > 
> > > > Hi,
> > > > 
> > > > I was wondering how Boost.Locale is related
> > > > to the standard message facet which is used
> > > > to translate messages. 
> > > 
> > > 
> > > The standard message catalogs allow to extract
> > > messages by integer identifiers but may use string
> > > identifiers and it is implementation defined
> > > 
> > > It is undefined how to load message facets
> > 
> > Well implementation defined doesn't mean undefined.
> > 
> 
> But it makes it useless as each compiler
> can do anything it wants.
> 
> > > or format them and so on.
> > 
> > The formatting can always be done on top of this facet, isn't it?
> > 
> 
> By formatting I mean the entire infrastructure of catalog
> formats, binary formats, message extracting software,
> user friendly translation tools like po-edit and so on.
> 
> > > It does not support plural forms and context.
> > 
> > I'm not an expert, but doesn't catalogs and the set
> > parameter can be used for your domain an context?
> > 
> 
> This is std::message::get function:
> 
> string_type get (catalog cat, int set, int msgid,
> const string_type&dfault) const;
> 
> 
> cat - is the "domain" in Boost.Locale
> set - is can be used as context but it is an integer
> and not some user friendly id - bad for localization
> msgid - is the identification of the specific message
> but still integer bad for localization
> 
> dfault - is the default returned string it is not found
> and it can be used as an alternative to msgid.
> 
> 
> Now: 
> 
> - if you want textual context you can't

Well, you can always use a map of textual context that give you the integer, isn't it?

> - if you want to get plural form you can't.

Why? The fact the interface doesn't manage explicitly with plurals doesn't mean you can not get them.

> So basically it is too weak and limited.
> 
> 
> > Respect to plural forms, how Boost.Locale manages with locales
> > that have 3 or 4 forms of plurals (If I understood your private
> > mail, Hebrew is an example of this)? I've the impression that
> > Boost.Locale manage simple plurals but not all kind of
> > plurals? 
> 
> It handles all kinds of purals.
> 
> > BTW, what is the criteria in Boost.Locale to
> > identify a plural form? 
> >
> 
> It uses in input parameter of actual number to identify one
> 
> When you call 
> 
> format(translate("File was opened {1} day ago",
> "File was opened {1} days ago",
> no_of_files) 
> % no_of_files
> 
> Which is basically, in Hebrew for example:
> 
> 
> translate("File was opened {1} day ago",
> "File was opened {1} days ago",
> no_of_files) 
> when no_of_files == 1 returns "Kovetz niftah lifney yom {1}"
> when no_of_files == 2 returns "Kovetz niftah lifney yomaim"
> when no_of_files <1 or >2 returns "Kovetz niftah lifney {1} yamim"
>
> And then format formats it with no_of_files. 
> 
> If the string is not in the dictionary then for no_of_files==1
> it returns "File was opened {1} day ago" and for no_of_files==2 it
> returns "File was opened {1} days ago"

Sorry, but I don't understand how this works, to which string are you referring to on "If the string is not in ...?. Could you show the catalog associated to this translation in English and in Hebrew? 

> > How your library manage plurals for message that have several parameters? For 
> >example
> > 
> > translate("%1 hours, %2 minutes, %3 seconds") % h % m % s
> > 
> 
> You do it in different way
> 
> format(translate("Format date with H-M-S","{1}, {2}, {3}")) 
> % format(translate("Format date with H-M-S","{1} hour","{1} hours")) 
> % format(translate("Format date with H-M-S","{1} minute","{1} minutes")) 
> % format(translate("Format date with H-M-S","{1} second","{1} seconds")) 

As a programmer, I would like a library that let me write just

translate("%1 hours, %2 minutes, %3 seconds") % h % m % s

As a translator, I would need to translate more than one string of course. 

> Basically you provide good context "Format date with H-M-S" and a basic pattern
> for formatting "{1}, {2}, {3}" which translator can alter then 
> you translate with same context three subpatterns each with its
> own plural form,
> 
> > > It is the most unless facet around.
> > 
> > What do you mean? That the scope is reduced?
> > 
> 
> It should be useless not unless.
> 
> In any case it is impossible to use it in real life.

I guess some people is using it now.

> > > > Note that the facet
> > > > interface work with integer identifiers
> > > > avoiding all the issues raised by the
> > > > get_text/translate functions
> > > > provided by Boost.Locale.
> > > >
> > > 
> > > Use of integer identifiers is the best
> > > way to screw the localization in the software.
> > > 
> > > What does 3456 means? Do you really think
> > > it is good to write translate(MY_MESSAGE_OPENING_FILE)
> > 
> > Why not? 
> > Note that we can also write translate(MyMessage::OpeningFile) if this seems 
> >clearer to you
> > 
> 
> Same problems as in real file you need quite a complicated
> strings and expressions. Many messages are not just "Open a file"
> but rather:
> 
> "You are going to connect to the untrusted web site {1} "
> "its original is unknown and you may be a victim of a scam"

I don't think it is good to include such messages in the code :(. This belongs to the translation part.

> So how would you put it into the code?
> 
> MyMessage::UntrustedWarning?
> 
> And if you have something slightly different like
> the encryption is too weak then programmers would write
> 
> MyMessage::UntrustedWarning2?
> 
> Beleive me this is what happens in real life..

I guess the programmer is able to find more appropriated symbolic names, don't you?

> See notes below about rules of thumb.
> 
> 
> > 
> > > No, never - never - never - never - never
> > > use such "constant" or "integer" identifiers.
> > 
> > I understand that some as you can find that the use of
> > integers scale worst than the use of strings as we need
> > to maintain constants unique on a given context,
> > but this can be checked on debug mode.
> > 
> 
> It is about maintainability and linguistics.

As far as I remember we didn't have maintenability issues.

> > Some time ago when I had to write a localization application,
> > we used integer identifier to log internationalizable messages.
> > This reduced drastically the size of the log. I guess only
> > this advantage was enough to take integers instead of strings,
> > for us of course. 
> >
> 
> If you really want short identifiers for specific cases, you for
> example can write things like
> 
> log() << "EINVAL" 
> 
> or
> 
> log() << "MSG::Inval"

This is not as bad as the long translation message, but is not yet optimal when storage could be an issue.

> > An advantage I see is that you need to concentrate all the message id of a
> > set/context in a single file so no need to have tools
> > that parse your code to get the strings to translate.
> > 
> 
> You need so many tools that the tool that extracts
> the strings from sources code is the minor one.
> 
> It is very important to have powerful translation
> tools that would allow you to merge translations
> work on them with built in spell checker and
> so on.
> 
> You do not work on translations today with a simple
> text editor.

As I said before, I was working with some years ago, and we didn't need so much tools.

> > BTW, how do you recover message translation
> > from a domain with your underlying implementation,
> > copy/paste or is there a possibility to have specific
> > files for specific domains, or there is a single
> > translation file by locale?
> >
> 
> It depends on your design.
> 
> If you for example have a single program just use a single
> domain named after your program, but if you have
> for example some independent component it may be
> used in its own domain.
> 
> In any case each dictionary is per locale (or language) and
> per domain.

Ok, I see. This is fine.

> > I've not take a look at your implementation yet
> > Please could you tell me when the translation file is read?
> > Is the file parsed only once and the translations stored on a cache?
> >
> 
> The dictionary parsed and loaded during generation of the locale
> then it is stored in the memory and not changed till
> the std::locale object is destroyed.

For long lived applications it could be needed to force the release of this memory when the default local change, isn't it?

> > > Always use natural text.
> > 
> > I think your natural language interface lets the user
> > to have the impression that anything is possible,
> > when a lot of limitations seem to be there as other
> > have already commented in this ML. 
> 
> The natural language interface is the most powerful.
> 
> > 
> > > > Is there any reason Boost.Locale
> > > > could not follow the standard design?
> > > 
> > > The standard message catalogs to weak
> > 
> > I would like to here the rationale of the standard
> > message design by someone that is aware of it
> > (some pointers will be welcome also).
> > 
> > 
> > > > What are the advantages of the Boost.Locale design?
> > > >
> > > 
> > > 1. Defined way to load and format catalogs
> > 
> > You could provide a defined way on top of this facet, isn't it?
> > 
> > > 2. Support of pural forms
> > 
> > Plural forms can be designed on top of the message facet?
> > 
> 
> No, New message facet required

You have added one, isn't it? If I'm not wrong gettext doesn't take care of plurals, and you have added something on top of.

> > > 3. Support of message-context
> > 
> > As I said, I suspect that the set parameter is interpreted as your context.
> 
> No see notes above.

I have copied here what you said about the set parameter.

> set - is can be used as context but it is an integer
> and not some user friendly id - bad for localization

so I gues this mean that yes, it supports message context.

> > > 4. Using natural language identifiers as keys

I have some use cases needing a more compact format.

> > See below. This is not always an advantage,
> > and as far as I see adds some constraints
> > on the interface so the tool can take care
> > to automatically extract the strings to translate.
> >
> 
> You are looking on the problem from a pure software
> engineer point of view, however when it comes
> to UI and Localization there are two important
> rules of thumb:
> 
> 1. Provide as much information as possible to 
> make life on the translator as easier as possible,
> for example:
> 
> a) Context
> 
> Instead of MyMessage::FileOpen
> 
> Provide: "File Opening Dialog", "Open"

Or FileOpeningDialog_Open

> b) The unit gettext provides an option to extract
> nearby comments from the source so in the code
> 
> // We open a file in CSV format with 
> // prices of the items.
> AddMenuItem(translate("File Opening Dialog", "Open"))
> 
> And the translator will see all the text!
> 
> 2. Assume as few as possible - make as generic interface
> 
> For example you have a dialogs.
> 
> How is this row?
> 
>  
> 
> How is this color?
> 
>  
> 
> 
> So you can translate:
> 
> translate("How is this row?");
> translate("How is this color");
> translate("Good");
> translate("Bad");
> 
> What is the problem with this?
> 
> Think about a minute before you 
> look behind...
> 
> Gender, in some languages row and color
> have different gender so Good and Bad
> should have different forms according to
> gender. So you need to write
> 
> translate("How is this row?");
> translate("About row","Good");
> translate("About row","Bad");
> translate("How is this color");
> translate("About color","Good");
> translate("About color","Bad");
> 
> This is what I'm talking about 
> assumptions.
> 
> Making integer identifiers would
> detach the strings from the context
> even more and it is bad.

I think the opposite, English could you think there is no gender issue. 

Letting the user write

translate("How is this row?");
translate("How is this color");
translate("Good");
translate("Bad");

is not good. I would prefer the interface force the use of context.

> So yes, you can use integers but it is VERY-BAD design.
> 
> > > 5. Convenense interface
> > What do you mean?
> > Could you compare both?
> > 
> 
> Yes
> 
> // get generation stage
> std::message::catalog domain_id = std::use_facet 
> >(l).open("domain",l);
> 
> // in use
> AddMenuItem(std::use_facet 
> >(std::locale()).get(domain_id,0,0,"Open File"))
> 
> // at close
> std::use_facet >(l).close(domain_id);
> 
> Or
> 
> boost::locale::generator gen;
> gen.add_messages_domain("domain");
> std::locale::global(gen(""));
> 
> // in use
> AddMenuItem(translate("Open File"));
> 
> // destroyed with the locale

Yes a translate manipulator simplifies the code and is very useful. 
Yes RAII is good, but I want also to be able to close it explicitly also. 

> Standard message catalog requires you to store somewhere the catalog variable
> while the boost.Locale messages facet has some default and allows to use
> a string based key for domain.

I'm not saying the standard can not be improved, but I think it would be better to build on top of it, instead of providing two interfaces that use incompatible catalogs.
Making internationalizable applications that use C++ internationalizable libraries using different catalogs would be a complex for the translator.

> > > More?
> > 
> > Well, I think that it would be great if you can add a complete
> > comparison of the interfaces and a rationale why you think your
> > design is superior on the documentation.
> >
> 
> Too many flaws, too many problems... If so I should
> write about 10-20 pages on flaws of all facets around

>From my side, it will be enough if you concentrate your effort on the message facet ;-)

> I have some small summary of problems but full side by side?
> Do you really need them?

I think it will be useful in your documentation, as you are proposing an alternative design. I also think that if you find the message facet is not usable in real life, you should make a standard proposal to improve it (Why not for TR2?). I'm sure you will have a lot of constructive feedback from some experts.

Best,
Vicente