Returning a WML tag table with .while

[Pentarctagon]

I'm trying to return a WML table of tags from a lua function, the idea being that it's similar to splitting WML between files and then including them in a main file via:

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{~add-ons/Addon/folder/file.cfg}

In my preload event I've defined the following:

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helper = wesnoth.require "lua/helper.lua"
tag = helper.set_wml_tag_metatable{}
action = helper.set_wml_action_metatable{}

wesnoth.dofile "~add-ons/Music/macros/_test.lua"

However the following code in _test.lua:

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function test()
  return tag.option
  {
    message = "&" .. "ball-green.png" .. "=" .. "Message",
    
    tag.command
    {
      tag.while
      {
        tag.variable
        {
          name = "music_repeating1",
          value = 1
        },
        
        tag.do
        {
          tag.message
          {
            speaker = "narrator",
            message = "",
            
            tag.option
            {
              message = "&" .. "ball-red.png" .. "=" .. "Message",
              
              tag.command
              {
                tag.set_variable
                {
                  name = "music_repeating1",
                  value = "$empty"
                }
              }
            }
          }
        }
      }
    }
  }
end

gives the error:

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_test.lua:8: <name> expected near 'while'

What is it expecting near tag.while?

[iceiceice]

I fooled around with this in the lua interpreter in 1.13.

Spoiler:

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Initializing Basic Lua Kernel...
Adding standard libs...
Adding error handler...
Adding gettext metatable...
Adding tstring metatable...
Adding boost function proxy...
Registering basic wesnoth API...
Redirecting print function...
Adding map_location table...
Adding rng tables...
Loading ilua...
Activated strict mode.
$ helper = wesnoth.require "lua/helper.lua"
tag = helper.set_wml_tag_metatable{}
action = helper.set_wml_action_metatable{}
$ helper
{shallow_literal=function: 0x5972d50,get_child=function: 0x5971a60,set_wml_action_metatable=function: 0x596bb70,child_range=function: 0x5940e40,set_wml_var_metatable=function: 0x5941550,parsed=function: 0x5972d20,modify_unit=function: 0x593fdd0,get_variable_array=function: 0x59419c0,set_wml_tag_metatable=function: 0x5941950,all_teams=function: 0x274c4f0,shuffle=function: 0x596bbe0,wml_error=function: 0x274c4c0,get_sides=function: 0x596f330,get_variable_proxy_array=function: 0x596bea0,literal=function: 0x596c780,adjacent_tiles=function: 0x596c710,rand=function: 0x596ccf0,shallow_parsed=function: 0x596ccc0,round=function: 0x592a9c0,set_variable_array=function: 0x596be70,get_user_choice=function: 0x596bee0 ... }
$ tag
table: 0x596bd20
$ action
table: 0x596bd70
$ tag.option
  {
    message = "&" .. "ball-green.png" .. "=" .. "Message",
    
    tag.command
    {
      tag.while
      {
        tag.variable
        {
          name = "music_repeating1",
          value = 1
        },
        
        tag.do
        {
          tag.message
          {
            speaker = "narrator",
            message = "",
            
            tag.option
            {
              message = "&" .. "ball-red.png" .. "=" .. "Message",
              
              tag.command
              {
                tag.set_variable
                {
                  name = "music_repeating1",
                  value = "$empty"
                }
              }
            }
          }
        }
      }
    }
<span color='#8888FF'>When parsing a string to lua,  a syntax error:
  [string "tag.option..."]:7: <name> expected near &apos;while&apos;</span>
$ tag.option
  {
    message = "&" .. "ball-green.png" .. "=" .. "Message",
    
    tag.command
    {
      tag.whjile
      {
        tag.variable
        {
          name = "music_repeating1",
          value = 1
        },
        
        tag.do
        {
          tag.message
          {
            speaker = "narrator",
            message = "",
            
            tag.option
            {
              message = "&" .. "ball-red.png" .. "=" .. "Message",
              
              tag.command
              {
                tag.set_variable
                {
                  name = "music_repeating1",
                  value = "$empty"
                }
              }
            }
          }
        }
      }
    }
<span color='#8888FF'>When parsing a string to lua,  a syntax error:
  [string "tag.option..."]:15: <name> expected near &apos;do&apos;</span>
$ tag.option
  {
    message = "&" .. "ball-green.png" .. "=" .. "Message",
    
    tag.command
    {
      tag.whjile
      {
        tag.variable
        {
          name = "music_repeating1",
          value = 1
        },
        
        tag.djo
        {
          tag.message
          {
            speaker = "narrator",
            message = "",
            
            tag.option
            {
              message = "&" .. "ball-red.png" .. "=" .. "Message",
              
              tag.command
              {
                tag.set_variable
                {
                  name = "music_repeating1",
                  value = "$empty"
                }
              }
            }
          }
        }
      }
    }
<span color='#8888FF'>When parsing a string to lua,  a syntax error:
  [string "tag.option..."]:38: &apos;}&apos; expected (to close &apos;{&apos; at line 2) near <eof></span>
$ tag.option
  {
    message = "&" .. "ball-green.png" .. "=" .. "Message",
    
    tag.command
    {
      tag.whjile
      {
        tag.variable
        {
          name = "music_repeating1",
          value = 1
        },
        
        tag.djo
        {
          tag.message
          {
            speaker = "narrator",
            message = "",
            
            tag.option
            {
              message = "&" .. "ball-red.png" .. "=" .. "Message",
              
              tag.command
              {
                tag.set_variable
                {
                  name = "music_repeating1",
                  value = "$empty"
                }
              }
            }
          }
        }
      }
    }
}
{'option',{[1]={'command',{[1]={'whjile',{{'variable',{name='music_repeating1',value=1}},{'djo',{[1]={...}}}}}}},message='&ball-green.png=Message'}}

I think that the problem is that you cannot use while or do as the names of table entries in lua, because they are reserved words. It seems like it is just failing to parse the way you want it to. Maybe there is some workaround you can use, like using the table insert function with string arguments or something. Probably not worth it though.

[Elvish_Hunter]

What is it expecting near tag.while?

Exactly as iceiceice said, while, do, if and else are reserved keywords in Lua, and as such cannot be used as function names. This is the same problem that I faced when refactoring the [if] tag to implement [elseif]: instead of writing

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wml_actions.if( cfg )

I had to access the table with the square brackets operator and assign an anonymous function:

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wml_actions["if"] = function( cfg )

In you case, the only possible workaround that comes to my mind is to write the while tag as a regular WML table, with all the brackets (and related mistakes ) that this solution requires.

[gfgtdf]

It is possible to do the same in his case:

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    function test()
      return tag.option
      {
        message = "&" .. "ball-green.png" .. "=" .. "Message",
       
        tag.command
        {
          tag["while"]
          {
            tag.variable
            {
              name = "music_repeating1",
              value = 1
            },
           
            tag["do"]
            {
              tag.message
              {
                speaker = "narrator",
                message = "",
               
                tag.option
                {
                  message = "&" .. "ball-red.png" .. "=" .. "Message",
                 
                  tag.command
                  {
                    tag.set_variable
                    {
                      name = "music_repeating1",
                      value = "$empty"
                    }
                  }
                }
              }
            }
          }
        }
      }
    end

[Pentarctagon]

It is possible to do the same in his case:

That worked, thanks.

A related question now that that's solved: Is there any kind of performance difference one way or the other compared to straight WML if I were to make something semi-complex this way?

[gfgtdf]

For most wml action like [message] or similar the time to execute the action is bigger than the time to parse the wml in lua or in wml, so that doesn't really matter. Otherwie local lua variables are much faster for calculating than wml varaibles. But this also only matters if you do a lot variable stuff.

But why do you want to use action.message with options? wesnoth.show_dialog is much cooler .

[Pentarctagon]

Currently 99% of the add-on is in WML, and the current extent of my lua knowledge is limited to basic string manipulation that WML can't do. So I figured it would be best to do this first to learn what's going on since it's really similar, then mess with moving stuff to show_dialog etc afterwards. I didn't want to trudge through something completely new and different only find out halfway through that it isn't actually possible due to something like tag.while (if there wasn't a workaround).

[gfgtdf]

Im quite sure that you can write everything that is possible in wml also with lua without a single [event] just with [lua].


Why do you want to port your code to lua?

[Pentarctagon]

Why do you want to port your code to lua?

It will hopefully be easier to desynchronize variables and certain actions if everything is in lua rather than trying to make some frankenstein mishmash of WML with embedded lua everywhere.

[Pentarctagon]

I started experimenting with show_dialog and I have a question about button ids:

What is a valid id? I have the following code:

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function test_menu()
  dialog =
  {
    tag.tooltip
    {
      id = "tooltip_large"
    },
    tag.helptip
    {
      id = "tooltip_large"
    },
    tag.grid
    {
      tag.row
      {
        tag.column
        {
          tag.button
          {
            id = "ok",
            label = "Exit",
            return_value = 0
          }
        }
      },
      tag.row
      {
        tag.column
        {
          tag.button
          {
            id = "cancel",
            label = "Mute",
            return_value = 1
          }
        }
      }
    }
  }
  
  return dialog
end

And then a loop for it elsewhere:

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        doTest = 1
        while doTest == 1 
        do
          doTest = wesnoth.show_dialog(test_menu())
        end

If the id of the first button's id is "ok" then I can exit the menu, but if I change the button's id to anything else like "exit" or "asdasda" then I can't.

[gfgtdf]

Any id is valid but some ids (like "ok") have some special meaning like 'close dialog on click'.

If you want to make a button that closed the dialog on click, another option is to add a value return_value=<integer> attribute to the button which then results in this integer beeing returned by show_dialog if the button was clicked.


EDIT: i just saw that you do have return_value, will look at the c++ code why it doesnt work.

EDIT2: ok it seems like '0' is th default value for return_value, so the cpp code cannot make a difference between 0 and not specifying return_value, just not using '0' as a return_value should fix the problem.

[Pentarctagon]

What worked:

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          tag.button
          {
            id = "exit",
            label = "Exit",
            return_value = 2
          }

What didn't work:

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          tag.button
          {
            id = "exit",
            label = "Exit",
            return_value = 0
          }

and

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          tag.button
          {
            id = "exit",
            label = "Exit"
          }

So it works if I return anything but the default value.