LuaWML/Variables

This page describes the LuaWML functions and helpers for handling WML variables and containers.

wesnoth.get_variable

• wesnoth.get_variable(var_name)

Loads a WML variable with the given qualified name (argument 1) and converts it into a Lua object. Returns nil if the name does not point to anything, a scalar for a WML attribute, and a table for a WML object. The format of the table is described in LuaWML#Encoding WML objects into Lua tables.

wesnoth.fire("store_unit", { variable="my_unit", { "filter", { id="hero" } } })
local heros_hp = wesnoth.get_variable("my_unit[0].hitpoints")
wesnoth.message(string.format("The 'hero' unit has %d hitpoints.", heros_hp))

Argument 2, if true, prevents the recursive conversion when the name points to an object; a fresh empty table is returned in this case. This is mainly used for writing proxy objects, e.g. in #helper.set_wml_var_metatable.

Note that, if the variable name happens to designate a sequence of WML objects, only the first one (index 0) is fetched. If all the WML objects with this name should have been returned, use #helper.get_variable_array instead.

wesnoth.set_variable

• wesnoth.set_variable(var_name, value)

Converts and stores a Lua object (argument 2) to a WML variable (argument 1). A WML object is created for a table, an attribute otherwise.

wesnoth.set_variable("my_unit.hitpoints", heros_hp + 10)

Setting a WML variable to nil erases it.

wesnoth.get_all_vars

• wesnoth.get_all_vars()

(Version 1.13.0 and later only) Returns all the WML variables currently set in form of a WML table. This function accepts no arguments.

for key, value in pairs( wesnoth.get_all_vars() ) do
    if type( value ) == "table" then
        print( key, value[1], value[2] )
    else
        print( key, value )
    end
end

wesnoth.wml_matches_filter

• wesnoth.wml_matches_filter(config, filter)

Test if a config matches a WML filter (as [filter_wml]).

helper.get_child

• helper.get_child(config, child_tag_name)

Returns the first sub-tag of a WML object with the given name.

local u = wesnoth.get_units({ id = "Delfador" })[1]
local costs = helper.get_child(u.__cfg, "movement_costs")
wesnoth.message(string.format("Delfador needs %d points to move through a forest.", costs.forest))

If a third parameter is passed, only children having a id attribute equal to it are considered.

helper.get_nth_child

(Version 1.13.2 and later only)

• helper.get_nth_child(config, child_tag_name, n)

Returns the nth sub-tag of a WML object with the given name.

helper.child_count

(Version 1.13.2 and later only)

• helper.child_count(config, child_tag_name)

Returns the number of children in the config with the given tag name.

helper.child_range

• helper.child_range(config, child_tag_name)

Returns an iterator over all the sub-tags of a WML object with the given name.

local u = wesnoth.get_units({ id = "Delfador" })[1]
for att in helper.child_range(u.__cfg, "attack") do
    wesnoth.message(tostring(att.description))
end

helper.child_array

(Version 1.13.2 and later only)

• helper.child_array(config, child_tag_name)

Like helper.child_range, but returns an array instead of an iterator. Useful if you need random access to the children.

helper.get_variable_array

• helper.get_variable_array(var_name)
• (Version 1.13.8 and later only) helper.get_variable_array(var_name [, context])

Fetches all the WML container variables with given name and returns a table containing them (starting at index 1). The context specifies where to get variables from. You can pass either a unit or a side as the context in order to get an array from the unit variables or side variables, respectively.

function get_recall_list(side)
    wesnoth.fire("store_unit", { x = "recall", variable = "LUA_recall_list" })
    local l = get_variable_array "LUA_recall_list"
    wesnoth.set_variable "LUA_recall_list"
    return l
end

helper.get_variable_proxy_array

• helper.get_variable_proxy_array(var_name)

Creates proxies for all the WML container variables with given name and returns a table containing them (starting at index 1). This function is similar to #helper.get_variable_array, except that the proxies can be used for modifying WML containers.

helper.set_variable_array

• helper.set_variable_array(varname, array)
• (Version 1.13.8 and later only) helper.set_variable_array(varname, array [, context])

Creates WML container variables with given name from given table. The context specifies where to put the variables. You can pass either a unit or a side as the context in order to set an array in the unit variables or side variables, respectively.

helper.set_variable_array("target", { {t=t1}, {t=t2}, {t=t3} })
-- target[0].t <- t1; target[1].t <- t2; target[2].t <- t3