monochromatic's lua thread

[monochromatic]

Finally, some progress! School has been choking me a part couple weeks, but nonetheless I've managed to squeeze some time into working on this. It's a replacement for LIMIT_RECRUITS and LIMIT_CONTEMPORANEOUS_RECRUITS, which I think is clunky. Here you can put it into a nice, clean tag and it actually works!

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--	Replacement for the LIMIT_RECRUIT and LIMIT_CONTEMPORANEOUS_RECRUITS macros
--	
--	Use in WML:
--	[event]
--		name = recruit,side turn
--	
--		[limit_recruits]
--			# SUF, don't use a [filter] tag
--			value = # number of limited recruits
--			cumulative = # whether the total units should be cumulative or not
--			# LIMIT_RECRUITS is cumulative, LIMIT_CONTEMPORANEOUS_RECRUITS is not
--			# default is no
--		[/limit_recruits]
--	[/event]

helper = wesnoth.require "lua/helper.lua"
wml_actions = wesnoth.wml_actions

function wml_actions.limit_recruits(cfg)
	local value = (tonumber(cfg.value)) or helper.wml_error("Missing or wrong required 'value' attribute in [limit_recruits]")
	local cumulative = cfg.cumulative
	
	local filter = wesnoth.get_units(cfg)
	if #filter >= value then
		for index,unit in ipairs(filter) do
			wml_actions.disallow_recruit { side = unit.side , type = unit.type }
		end
	elseif not cumulative then
		if #filter < value then
			for index,unit in ipairs(filter) do
				wml_actions.allow_recruit { side = unit.side , type = unit.type }
			end
		end
	end
end

[Elvish_Hunter]

Nice work, e_s I see two things that can be improved here:

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local number = cfg.number or helper.wml_error("Missing required 'value' attribute in [limit_recruits]")

I usually tend to place here a tonumber() ( tonumber(cfg.number) ). Why? Because if someone attempts to feed a string value (like number=fifteen), tonumber returns nil (because it fails to convert it to a numerical value) and allows you to fire an error message like

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helper.wml_error("Missing or wrong required 'value' attribute in [limit_recruits]")

Also,

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local cumulative = cfg.cumulative or "false"

There is usually no need to declare it as false (unless you have a good reason to do so, like doing a different action if cumulative == nil). If cfg.cumulative isn't supplied by user, it will be automatically nil; and both nil and false are considered false by Lua, everything else is true (including 0 and "").
By the way, your "false" between quotes is considered a string value by Lua, and strings are always true; special values like true, false and nil must not have quotes. At the end, removing or "false" will allow you to replace

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elseif cumulative == "false" then

with

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elseif not cumulative then

Much simpler, no?

[monochromatic]

Awesome! Edited my post above with also a minor flavor change. Interesting to know that Lua reads "false" as a string. nil might be easier in the future.

[monochromatic]

Okay, question here. I've seen this mentioned a number of times and I've read it on the wiki. What does a "proxy" unit/array refer to exactly? Thanks.

[Anonymissimus]

It's an "accessor" to a C++ variable or object. In the units section in LuaWMl I had written about it.

[monochromatic]

Okay, new question: is there a way to divide two numbers and guarantee it's not a floating point value?
For example: x = 9 / 4 --x = 2.25
Is there a way to make it so something like that will be 2 rather than 2.25 or whatever? It helps for hitpoints/moves etc. Also if there isn't, is there a workaround?
I have a feeling I'm missing something soo obvious.

[melinath]

Something like math.floor?

[monochromatic]

Totally didn't know that! /me wonders where 'floor' comes from..

[melinath]

Imagine a building with multiple stories. Each story represents an integer value - or more precisely, each story represents the space between two integers. Then for each story, the floor is one integer while the ceiling is another. Hence math.floor and math.ceil.

[Elvish_Hunter]

For example: x = 9 / 4 --x = 2.25

To complete the answer with a concrete example, here there is what happens to the Lua prompt with and without rounding functions:

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linux@linux-desktop:~$ lua
Lua 5.1.4  Copyright (C) 1994-2008 Lua.org, PUC-Rio
> print ( 9 / 4 )
2.25
> print ( math.floor ( 9 / 4 ) )
2
> print ( math.ceil ( 9 / 4 ) )
3

As you can see, floor rounds down to the nearest integer, while ceil rounds up to the nearest integer.

[monochromatic]

Awesome! Okay new question, I have this line of code which is giving me errors:

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local frostbite_units = wesnoth.get_units { side = side_number , { "not" , { id = "Buggles" }} , { "filter_location" , { terrain = "A*,*^F*a,Ms,Ha" , { "not" , { terrain = "*^V*" }}}}}

So the engine is giving me some errors about it being a table, not a WML table (or the other way around). How do I store the unit properly? I've seen it work without subtags.

[Elvish_Hunter]

Hmm... perhaps the problem is elsewhere, as I copied your line in this tag (I changed the terrain code only, because the map that I used has no snow):

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function wml_actions.frost(cfg)
	local frostbite_units = wesnoth.get_units { side = side_number , { "not" , { id = "Buggles" }} , { "filter_location" , { terrain = "G*" , { "not" , { terrain = "*^V*" }}}}}
	for index, unit in ipairs ( frostbite_units ) do
		print ( unit.id )
	end
end

and it returned me this in the console:

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Yeti-55
Wose-57
Wose-59
Elvish Archer-63
Elvish Archer-65
Wose-67
Dwarvish Guardsman-69

clear sign that units were acquired correctly. By the way, I'm on 1.9.5+svn, 49123M.

[monochromatic]

Okay then the problem is else-ware. Thanks!
EDIT: Fixed it! It was something wrong with my for loop.