Creating translatable strings

[CIB]

I'm not sure how to do this.

Obviously: "foo" .. bar .. "baz" is not going to work

Given that V is a WML variable metatable, I tried:

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V.bar = bar
V.message = _ "foo $bar baz"

But oddly, this doesn't seem to do variable substitution immediately, which will cause strings generated in loops to be messy. For example:

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for _, value in ipairs(values) do
 V.value = value
 V.message = V.message .. "List item: $value\n"
end

Would just print the last list item over and over again.

Finally, there's string.format, like

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V.value = string.format(_ "foo %s baz", bar)

But the obvious problem is that if the translated string shuffles variables around, it'll break.

[8680]

What about this?

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bar = "..."
s = tostring(_ "foo {bar} baz"): gsub("{([^{}]+)}", _ENV)

It won’t work for WML variables though. It may work for WML variables (and only WML variables) if you replace _ENV with the WML variable metatable, but why use WML variables in Lua?

[Elvish_Hunter]

Translatable string are not normal strings, but a special data type. You must cast them with tostring() to use them (with the exception of the .. operator). See http://wiki.wesnoth.org/LuaWML:Display# ... textdomain :

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wesnoth.message(string.format(tostring(_ "You gain %d gold."), amount))

Alternatively, to perform variable substitution with the $ symbol, you can take a look at wesnoth.tovconfig(). See http://wiki.wesnoth.org/LuaWML:Events#wesnoth.tovconfig.

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for _, value in ipairs(values) do
 V.value = value
 V.message = V.message .. "List item: $value\n"
end

Also, variable names that start with _ are reserved for constants as a convention. Don't try to use obscure variable names to save typing, or you'll end up typing more to fix bugs (it always happens to me ). Replace _ with "index" or "i", even if you don't plan to use it in the for cycle.

[CIB]

What about this?

Code: Select all

bar = "..."
s = tostring(_ "foo {bar} baz"): gsub("{([^{}]+)}", _ENV)

It won’t work for WML variables though. It may work for WML variables (and only WML variables) if you replace _ENV with the WML variable metatable, but why use WML variables in Lua?

If this does what I think it does(that's some very compressed code right there), that's an excellent idea and it'll remain compatible with variable re-ordering. And yes, using WML variables was only a workaround and maybe a tribute to translators who are used to that way. (The $ syntax, not the origin of the variables)

@Elvish_Hunter: Ahh, I didn't realize that, though I guess that's because for my test cases it didn't matter.

[CIB]

Okay, I tried to make life simple on me, but it backfired:

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-- custom textdomain function that'll return a translator that
-- does variable substitution as well as translation
helper.textdomain = function(domain)
	local translator = wesnoth.textdomain(domain)
	return function(str)
		return tostring(translator(str)): gsub("{([^{}]+)}", getfenv(2))
	end
end

_ENV won't work because obviously I need the environment of the caller, and getfenv doesn't exist anymore in lua 5.2. What now?

[Elvish_Hunter]

Okay, I tried to make life simple on me, but it backfired:

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-- custom textdomain function that'll return a translator that
-- does variable substitution as well as translation
helper.textdomain = function(domain)
	local translator = wesnoth.textdomain(domain)
	return function(str)
		return tostring(translator(str)): gsub("{([^{}]+)}", getfenv(2))
	end
end

_ENV won't work because obviously I need the environment of the caller, and getfenv doesn't exist anymore in lua 5.2. What now?

I forgot to say that the only exception to the "no underscore variables" is the translation marker, that must always be the underscore _ .
Try in this way:

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-- #textdomain "my-campaign"
_ = wesnoth.textdomain( "my-campaign" )

local test = wesnoth.get_variable( "my_variable_name" )
wesnoth.message( string.format( tostring( _"Item: %s" ), test ) )

To retrieve a WML variable, instead of complicating it with metatables, just use wesnoth.get_variable, passing the WML variable name as argument. A different procedure is required for WML arrays, but let's do things one step per time.
Then, pass the string with the formatting codes and the translation marker to tostring. This will, in turn, pass the translated string, as well as all the other values for substitution, to string.format. And it won't break if the %s is moved around the translated string, but only in case the translator decided, for some unknown reason, to remove the %s from the .po file.

[8680]

_ENV won't work because obviously I need the environment of the caller, and getfenv doesn't exist anymore in lua 5.2. What now?

Here are some more possibilities.

And it won't break if the %s is moved around the translated string, but only in case the translator decided, for some unknown reason, to remove the %s from the .po file.

What if there are multiple variables to be interpolated, and translation necessitates changing their order?

[Elvish_Hunter]

What if there are multiple variables to be interpolated, and translation necessitates changing their order?

That may be an issue, considering that Lua applies the formatting flags in sequence. In that case, or the translators try to avoid altering the order of the formatting fields (not always possible), or using a series of string.gsub() may become a viable option.
There may be other possible solutions, of course.