Ctx & Lua: determination of the language being used

Ctx & Lua: determination of the language being used

[Procházka Lukáš Ing. - Pontex s. r. o.]

Hello,

how to determine the current language being used in Ctx source via Lua? I mean soumething like:

---
\mainlanguage[cz]

\starttext
   AAA

   \startluacode
     if     context.mainlanguage == "cz" then -- Do something specific
       context("Ahoj!")
     elseif context.mainlanguage == "en" then -- Do something specific
       context("Hello!")
     else
     end
   \stopluacode
\stoptext
---

So is there something like 'context.mainlanguage' or 'context.mainlanguage()' or 'tex.mainlanguage' or ...?

Best regards,

Lukas


-- 
Ing. Lukáš Procházka [mailto:LPr@pontex.cz]
Pontex s. r. o.      [mailto:pontex@pontex.cz] [http://www.pontex.cz]
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Re: Ctx & Lua: determination of the language being used

[Wolfgang Schuster]

Am 25.11.2010 um 12:49 schrieb Procházka Lukáš Ing. - Pontex s. r. o.:

> Hello,
> 
> how to determine the current language being used in Ctx source via Lua? I mean soumething like:
> 
> ---
> \mainlanguage[cz]
> 
> \starttext
>  AAA
> 
>  \startluacode
>    if     context.mainlanguage == "cz" then -- Do something specific
>      context("Ahoj!")
>    elseif context.mainlanguage == "en" then -- Do something specific
>      context("Hello!")
>    else
>    end
>  \stopluacode
> \stoptext
> ---
> 
> So is there something like 'context.mainlanguage' or 'context.mainlanguage()' or 'tex.mainlanguage' or ...?

\mainlanguage[...] -> \currentmainlanguage
\language[...]     -> \currentlanguage

Wolfgang

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Re: Ctx & Lua: determination of the language being used

[Taco Hoekwater]

On 11/25/2010 01:13 PM, Wolfgang Schuster wrote:
>
> Am 25.11.2010 um 12:49 schrieb Procházka Lukáš Ing. - Pontex s. r. o.:
>
>> Hello,
>>
>> how to determine the current language being used in Ctx source via Lua? I mean soumething like:
>>
>> ---
>> \mainlanguage[cz]
>>
>> \starttext
>>   AAA
>>
>>   \startluacode
>>     if     context.mainlanguage == "cz" then -- Do something specific
>>       context("Ahoj!")
>>     elseif context.mainlanguage == "en" then -- Do something specific
>>       context("Hello!")
>>     else
>>     end
>>   \stopluacode
>> \stoptext
>> ---
>>
>> So is there something like 'context.mainlanguage' or 'context.mainlanguage()' or 'tex.mainlanguage' or ...?
>
> \mainlanguage[...] ->  \currentmainlanguage
> \language[...]     ->  \currentlanguage

For the benefit of the mailing list archive, this means you
can write in lua:

    if "\currentmainlanguage"=="cz" then

Except that that will not work because 'cz' is just an alias for 'cs',
so you should test for that instead:


     if "\currentmainlanguage"=="cs" then
       context("Ahoj!")
     elseif "\currentmainlanguage"=="en" then
       context("Hello!")

Best wishes,
Taco



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Re: Ctx & Lua: determination of the language being used

[Procházka Lukáš Ing. - Pontex s. r. o.]

... Thanks to both. So -

On Thu, 25 Nov 2010 13:31:36 +0100, Taco Hoekwater <taco@elvenkind.com> wrote:

> On 11/25/2010 01:13 PM, Wolfgang Schuster wrote:
>>
>> Am 25.11.2010 um 12:49 schrieb Procházka Lukáš Ing. - Pontex s. r. o.:
>>
>>> Hello,
>>>
>>> how to determine the current language being used in Ctx source via Lua? I mean soumething like:
>>>
>>> ---
>>> \mainlanguage[cz]
>>>
>>> \starttext
>>>   AAA
>>>
>>>   \startluacode
>>>     if     context.mainlanguage == "cz" then -- Do something specific
>>>       context("Ahoj!")
>>>     elseif context.mainlanguage == "en" then -- Do something specific
>>>       context("Hello!")
>>>     else
>>>     end
>>>   \stopluacode
>>> \stoptext
>>> ---
>>>
>>> So is there something like 'context.mainlanguage' or 'context.mainlanguage()' or 'tex.mainlanguage' or ...?
>>
>> \mainlanguage[...] ->  \currentmainlanguage
>> \language[...]     ->  \currentlanguage
>
> For the benefit of the mailing list archive, this means you
> can write in lua:
>
>     if "\currentmainlanguage"=="cz" then
>
> Except that that will not work because 'cz' is just an alias for 'cs',
> so you should test for that instead:
>
>
>      if "\currentmainlanguage"=="cs" then
>        context("Ahoj!")
>      elseif "\currentmainlanguage"=="en" then
>        context("Hello!")
>
> Best wishes,
> Taco

- In standalone Lua, the "\c" would be read (translated) as "c", as "\c" is not a valid escape sequence. See the test:

---
Microsoft Windows XP [Verze 5.1.2600]
(C) Copyright 1985-2001 Microsoft Corp.

C:\Lukas\ConTeXt\Samples\LuaTest>lua
Lua 5.1.4  Copyright (C) 1994-2008 Lua.org, PUC-Rio
> a="\currentmainlanguage"
> =a
currentmainlanguage
> =("\currentmainlanguage"=="currentmainlanguage")
true -- SO "\c" BECOMES "c"
---

So does it mean that "\<char>" (in the beginning of a string) in Lua for ConTeXt is a "hack" which expands a (Con)TeX(t) internal value (in the case that <char> is not a valid escape char)?

- If so, how to get an internal (Con)TeX(t) value which begins with a valid escape <char>, e.g. 't', so e.g. "\textwidth"? ("\t" should become <tab> in this case, or am I wrong?)

(Where to read about? I've been searching in luatexref-t.pdf...)

Lukas

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Re: Ctx & Lua: determination of the language being used

[Taco Hoekwater]

On 11/25/2010 02:16 PM, Procházka Lukáš Ing. - Pontex s. r. o. wrote:
>
> So does it mean that "\<char>" (in the beginning of a string) in Lua for
> ConTeXt is a "hack" which expands a (Con)TeX(t) internal value (in the
> case that <char> is not a valid escape char)?

No, nothing as complicated as that: \currentmainlanguage is an
expandable macro, so it simply expands to its actual content: cs

This also means that my proposed solution will not work if you put
it in a separate lua file: you have to convert it to a lua function
in that case that takes \currentmainlanguage as an argument.

Best wishes,
Taco
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Re: Ctx & Lua: determination of the language being used

[Procházka Lukáš Ing. - Pontex s. r. o.]

On Thu, 25 Nov 2010 14:22:18 +0100, Taco Hoekwater <taco@elvenkind.com> wrote:

> On 11/25/2010 02:16 PM, Procházka Lukáš Ing. - Pontex s. r. o. wrote:

> No, nothing as complicated as that: \currentmainlanguage is an
> expandable macro, so it simply expands to its actual content: cs
>
> This also means that my proposed solution will not work if you put
> it in a separate lua file: you have to convert it to a lua function
> in that case that takes \currentmainlanguage as an argument.

... And using this in a separate file is also what I'd need. So do I have to do something like:

--- A.mkiv
\startluacode
    function currentmainlanguage() return "\currentmainlanguage" end

    -- Or:

    the_currentmainlanguage = "\currentmainlanguage"

    dofile("A.lua")
\stopluacode
---

And:

--- A.lua
if currentmainlanguage() == "cs" then
-- Or: if the_currentmainlanguage = "cs" then

    -- Something
end
---

OK?

(Suggestion: Wouldn't be nice to have function(s) or variable(s) like e.g. 'context.environment["currentmainlanguage"]' or something like this?)

Best regards,

Lukas


(To Taco: Sorry, I sent the same message to your private address first.)

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Re: Ctx & Lua: determination of the language being used

[Taco Hoekwater]

On 11/25/2010 02:43 PM, Procházka Lukáš Ing. - Pontex s. r. o. wrote:
> ... And using this in a separate file is also what I'd need. So do I
> have to do something like:

Something like that, yes. But it depends a little on what you
want to do: because \currentmainlanguage expands, you will
get the value that is active during the first scan of the
lua code block, which may not be what you want, but it is hard
to judge without the actual use case.

> (Suggestion: Wouldn't be nice to have function(s) or variable(s) like
> e.g. 'context.environment["currentmainlanguage"]' or something like this?)

Yes, agreed, something like that would be useful. The same applies to
some other things, like color and active modes. Some of these are
probably there already, but it would be nice if they were documented.


Best wishes,
Taco
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Re: Ctx & Lua: determination of the language being used

[Hans Hagen]

On 25-11-2010 4:13, Taco Hoekwater wrote:
> On 11/25/2010 02:43 PM, Procházka Lukáš Ing. - Pontex s. r. o. wrote:
>> ... And using this in a separate file is also what I'd need. So do I
>> have to do something like:
>
> Something like that, yes. But it depends a little on what you
> want to do: because \currentmainlanguage expands, you will
> get the value that is active during the first scan of the
> lua code block, which may not be what you want, but it is hard
> to judge without the actual use case.
>
>> (Suggestion: Wouldn't be nice to have function(s) or variable(s) like
>> e.g. 'context.environment["currentmainlanguage"]' or something like
>> this?)
>
> Yes, agreed, something like that would be useful. The same applies to
> some other things, like color and active modes. Some of these are
> probably there already, but it would be nice if they were documented.

it's not so hard to interface that but we need to pick up the current value

     \ctxlua{tex.sprint(languages.numbers[1])}

however, tex does not privide access to the current language so i'd have 
to introduce an extra counter at the tex end

anyhow, for the moment you can use

languages.numbers[tex.count.mainlanguagenumber]

which probably gives you wat you want: en

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Re: Ctx & Lua: determination of the language being used

[Taco Hoekwater]

On 11/25/2010 04:57 PM, Hans Hagen wrote:
>
> however, tex does not privide access to the current language

It does: \ctxlua{print(tex.language)}


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