[FR] Setting flags with Lua

[sevu]

Flags can be read, but not changed in Lua, e.g. this isn't accepted: wesnoth.sides[1].flag="hjbd"
That's as documented in the wiki, but I guess it would be good to change flags without WML.

[gfgtdf]

I think there is a function for this although it has a rather confusing Name. But I agree that it should be added.

[gfgtdf]

@jostephd

i think you have to call game_display_->reinit_flags_for_side(team_num); afterwards.

[gfgtdf]

reopening for now.

[jostephd]

Thanks for catching that. That's what I get for testing the flag_icon setter but not the flag setter :(

I tried this patch:

patch

diff --git a/src/scripting/lua_team.cpp b/src/scripting/lua_team.cpp
index ac4693a29ff..f653ddf9fae 100644
--- a/src/scripting/lua_team.cpp
+++ b/src/scripting/lua_team.cpp
@@ -130,6 +130,12 @@ static int impl_side_set(lua_State *L)
 	team &t = luaW_checkteam(L, 1);
 	char const *m = luaL_checkstring(L, 2);
 
+	const auto& reinit_flag_for_team = [&L] (const team& t) -> void {
+		auto* disp = lua_kernel_base::get_lua_kernel<game_lua_kernel>(L).get_display();
+		if(disp) {
+			disp->reinit_flags_for_side(t.side());
+		}
+	};
 	// Find the corresponding attribute.
 	modify_int_attrib("gold", t.set_gold(value));
 	modify_tstring_attrib("objectives", t.set_objectives(value, true));
@@ -141,17 +147,17 @@ static int impl_side_set(lua_State *L)
 	modify_bool_attrib("objectives_changed", t.set_objectives_changed(value));
 	modify_bool_attrib("hidden", t.set_hidden(value));
 	modify_bool_attrib("scroll_to_leader", t.set_scroll_to_leader(value));
-	modify_string_attrib("flag", t.set_flag(value));
+	modify_string_attrib("flag", {
+		t.set_flag(value);
+		reinit_flag_for_team(t);
+	});
 	modify_string_attrib("flag_icon", t.set_flag_icon(value));
 	modify_tstring_attrib("user_team_name", t.change_team(t.team_name(), value));
 	modify_string_attrib("team_name", t.change_team(value, t.user_team_name()));
 	modify_string_attrib("controller", t.change_controller_by_wml(value));
 	modify_string_attrib("color", {
-		auto* disp = lua_kernel_base::get_lua_kernel<game_lua_kernel>(L).get_display();
 		t.set_color(value);
-		if(disp) {
-			disp->reinit_flags_for_side(t.side());
-		}
+		reinit_flag_for_team(t);
 	});
 	modify_string_attrib("defeat_condition", t.set_defeat_condition_string(value));
 	modify_int_attrib("carryover_percentage", t.set_carryover_percentage(value));
diff --git a/src/team.hpp b/src/team.hpp
index 909b44cd298..21e700bc6dc 100644
--- a/src/team.hpp
+++ b/src/team.hpp
@@ -254,6 +254,7 @@ public:
 
 	CONTROLLER controller() const { return info_.controller; }
 	const std::string& color() const { return info_.color; }
+	/// @note Call display::reinit_flag_for_team() after calling this
 	void set_color(const std::string& color) { info_.color = color; }
 	bool is_empty() const { return info_.controller == CONTROLLER::EMPTY; }
 
@@ -300,6 +301,7 @@ public:
 	const std::string& flag() const { return info_.flag; }
 	const std::string& flag_icon() const { return info_.flag_icon; }
 
+	/// @note Call display::reinit_flag_for_team() after calling this
 	void set_flag(const std::string& flag) { info_.flag = flag; }
 	void set_flag_icon(const std::string& flag_icon) { info_.flag_icon = flag_icon; }
 

With this patch, setting flag_icon and color works, but setting flag does not. The lambda is fine, since setting color works. What's missing?

I'll revert the setter in the meantime until it's fixed.

[gfgtdf]

With this patch, setting flag_icon and color works, but setting flag does not. The lambda is fine, since setting color works. What's missing?

i don't see anything wrong, maybe you did a mistake when testing?

[CelticMinstrel]

See my comment on 9bd717c for a probable explanation. Though I think @gfgtdf pretty much covered it as well.

More to the point, the premise of this issue report is wrong - it is already possible to change the flag in Lua. (Not sure about flag_icon but definitely flag can be changed.)

[jostephd]

@CelticMinstrel Yes, I did test that setting flag_icon works. I said so in a previous comment. Could it work in some cases and not others, or something?

OK, so the setter for flag needs to do what the function you mentioned does, whatever that is.

Unrelated, I noticed that after doing wesnoth.set_terrain(10, 10, 'Ss'), the hex does get swamp stats but isn't redrawn. How to fix that? I've tried :refresh.

[gfgtdf]

Unrelated, I noticed that after doing wesnoth.set_terrain(10, 10, 'Ss'), the hex does get swamp stats but isn't redrawn. How to fix that? I've tried :refresh.

you call [redraw] iirc. wesnoth.set_terrain does nto do that after perofrmance reasons, but its called at then of every [event] iirc.

what the function you mentioned does, whatever that is.

is basically just calls reinit_flags_for_side, that's what you ahve already added

[CelticMinstrel]

Well, what I mentioned in the comment applies to flag and color, not flag and flag_icon. So flag_icon being added as a modifiable attribute is fine.

I don't think we need setters for flag and color since the function exists, and having setters might mislead people into thinking it's simple write when in fact it's also invalidating a cache.

[jostephd]

i don't see anything wrong, maybe you did a mistake when testing?

No, I see the problem. set_side_id uses side-1, the C++ function I patched doesn't do the -1. For some reason setting the color does work despite that, but setting the flag doesn't. With the following patch, both set_side_id and assignments work to change both flag and color.

revised patch

diff --git a/src/scripting/lua_team.cpp b/src/scripting/lua_team.cpp
index 1d9ee1685ef..f6a4fa5d191 100644
--- a/src/scripting/lua_team.cpp
+++ b/src/scripting/lua_team.cpp
@@ -130,6 +130,12 @@ static int impl_side_set(lua_State *L)
 	team &t = luaW_checkteam(L, 1);
 	char const *m = luaL_checkstring(L, 2);
 
+	const auto& reinit_flag_for_team = [&L] (const team& t) -> void {
+		auto* disp = lua_kernel_base::get_lua_kernel<game_lua_kernel>(L).get_display();
+		if(disp) {
+			disp->reinit_flags_for_side(t.side() - 1);
+		}
+	};
 	// Find the corresponding attribute.
 	modify_int_attrib("gold", t.set_gold(value));
 	modify_tstring_attrib("objectives", t.set_objectives(value, true));
@@ -141,16 +147,17 @@ static int impl_side_set(lua_State *L)
 	modify_bool_attrib("objectives_changed", t.set_objectives_changed(value));
 	modify_bool_attrib("hidden", t.set_hidden(value));
 	modify_bool_attrib("scroll_to_leader", t.set_scroll_to_leader(value));
+	modify_string_attrib("flag", {
+		t.set_flag(value);
+		reinit_flag_for_team(t);
+	});
 	modify_string_attrib("flag_icon", t.set_flag_icon(value));
 	modify_tstring_attrib("user_team_name", t.change_team(t.team_name(), value));
 	modify_string_attrib("team_name", t.change_team(value, t.user_team_name()));
 	modify_string_attrib("controller", t.change_controller_by_wml(value));
 	modify_string_attrib("color", {
-		auto* disp = lua_kernel_base::get_lua_kernel<game_lua_kernel>(L).get_display();
 		t.set_color(value);
-		if(disp) {
-			disp->reinit_flags_for_side(t.side());
-		}
+		reinit_flag_for_team(t);
 	});
 	modify_string_attrib("defeat_condition", t.set_defeat_condition_string(value));
 	modify_int_attrib("carryover_percentage", t.set_carryover_percentage(value));
diff --git a/src/team.hpp b/src/team.hpp
index 909b44cd298..21e700bc6dc 100644
--- a/src/team.hpp
+++ b/src/team.hpp
@@ -254,6 +254,7 @@ public:
 
 	CONTROLLER controller() const { return info_.controller; }
 	const std::string& color() const { return info_.color; }
+	/// @note Call display::reinit_flag_for_team() after calling this
 	void set_color(const std::string& color) { info_.color = color; }
 	bool is_empty() const { return info_.controller == CONTROLLER::EMPTY; }
 
@@ -300,6 +301,7 @@ public:
 	const std::string& flag() const { return info_.flag; }
 	const std::string& flag_icon() const { return info_.flag_icon; }
 
+	/// @note Call display::reinit_flag_for_team() after calling this
 	void set_flag(const std::string& flag) { info_.flag = flag; }
 	void set_flag_icon(const std::string& flag_icon) { info_.flag_icon = flag_icon; }
 

I don't think we need setters for flag and color since the function exists, and having setters might mislead people into thinking it's simple write when in fact it's also invalidating a cache.

We already have a setter for color, so we can either add a setter for flag too for consistency, or deprecate the color setter at level 1. I don't have an opinion as to which course of action to take. I assume we should at least add the missing -1 to the color setter even if we don't add a flag setter.

[jostephd]

set_side_id uses side-1, the C++ function I patched doesn't do the -1

By the way, can we come up with a way to make this sort of bug impossible?

[CelticMinstrel]

I recall making a pass for that purpose, though it likely never got merged... the basic approach would be to not directly expose the sides array anywhere, so that the exposed API is exclusively 1-based. Then you only have to worry about the -1 in functions internal to... I think it was the model? The game map or something?

[gfgtdf]

revised patch

I think i'd also prefer if instead reinit_flags_for_side was changed to use side number of instead of indicies to the array.

We already have a setter for color, so we can either add a setter for flag too for consistency, or deprecate the color setter at level 1

I still say the setts are nice to have, celmins main argument, ('one does not expect a real computation form a setter' if i understood correctly) is for this case not really relevant here since one usually does not set flag/color in a loop such that performance here would matter. Also if we even come to the situation where it would matter we can probably change the implementation to a laze calculation of that image where these setts would become simple.

[CelticMinstrel]

I think i'd also prefer if instead reinit_flags_for_side was changed to use side number of instead of indicies to the array.

It absolutely should be, but that's not really in scope for the PR.

[jostephd]

It absolutely should be, but that's not really in scope for the PR.

Agreed.

What about the other questions, though? As I wrote:

We already have a setter for color, so we can either add a setter for flag too for consistency, or deprecate the color setter at level 1. I don't have an opinion as to which course of action to take. I assume we should at least add the missing -1 to the color setter even if we don't add a flag setter.

In further consideration I think I prefer to add a setter for flag, @gfgtdf's argument convinced me.