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POObject assignment Lua
 

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  1. POObject assignment Lua
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    <p>I have a problem similar to this one: <a href="https://stackoverflow.com/questions/15560813/lua-and-corona-error-attempt-to-call-method-a-nil-value-driving-me-craz">LUA and Corona error: Attempt To Call Method &#39; &#39; (A Nil Value) - Driving Me Crazy</a> I have a TCell class:</p> <pre><code>local TCell={}; local cell_mt = { __index=TCell }; function TCell.new(_contents_name,_x,_y) ... local ncell= { ... }; function ncell:setup() ... end ncell:setup(); return setmetatable(ncell,cell_mt); end return TCell; </code></pre> <p>I have 2d array of TCell references called cells. When I assign </p> <pre><code>cells[ind1][ind2]=cells[ind3][ind4] </code></pre> <p>cells[ind1][ind2] begins to lose some properties. If I understood the link above correctly it's caused by losing the metatable association. Do I need to use setmetatable another time? How can I do it if the assignment is not done in the TCell body?</p> <p>upd.</p> <pre><code>reset_metatable=function(target) return setmetatable(target,cell_mt); end; cells[ind1][ind2]=cells[ind3][ind4]; cells[ind1][ind2]=cells[ind1][ind2]:reset_metatable(); </code></pre> <p>isn't really helpful. upd2: deleted all code not connected with camera. Camera and TCell have no enterframe. The problem seems to be in metatables. Output gives NOW 6 1 width i 50 and after it START NOW 6 1 width is nil</p> <pre><code>----------------------------------------------------------------------------------------- -- -- Main Cycle -- ----------------------------------------------------------------------------------------- local storyboard = require( "storyboard" ) local scene = storyboard.newScene() -- include Corona's "physics" library local physics = require "physics" --control_circle=display.newImageRect(C.INTERFACE_DIR..C.INTERFACE_CONTROL_CIRCLE or C.EMPTY_IMAGE,C.CARS_W,C.CARS_W,true); local events_added=false; stage_frames=0; physics.start(); physics.pause() physics.setGravity( 0,0); local PCar=require("TCar") local PBiped=require("TBiped"); local PCell=require("TCell"); local control_circle_len; local cells={}; local cells_w,cells_h; local wshift,hshift=-(C.SCREEN_THEORETICAL_W-C.SCREEN_W)/2,-(C.SCREEN_THEORETICAL_H-C.SCREEN_H)/2; -------------------------------------------- -- forward declarations and other locals ----------------------------------------------------------------------------------------- -- BEGINNING OF YOUR IMPLEMENTATION -- -- NOTE: Code outside of listener functions (below) will only be executed once, -- unless storyboard.removeScene() is called. -- ----------------------------------------------------------------------------------------- local wsells,hcells=(C.SCREEN_W-C.SCREEN_W%C.LANDSCAPE_CELL_W)/C.LANDSCAPE_CELL_W+1,(C.SCREEN_H-C.SCREEN_H%C.LANDSCAPE_CELL_H)/C.LANDSCAPE_CELL_H+1; local dfd=false; local function manage_cells(cmx,cmy) --print("#",cmx,cmy); if((cmx==0 and cmy==0) or dfd) then return; end local cells_shift_w,cells_shift_h=0,0; if(cmx&gt;=0) then for i=cells_w,1,-1 do if(cells[i][1]:out_of_borders_w()==true) then cells_shift_w=cells_shift_w+1; else break; end end else for i=1,cells_w,1 do if(cells[i][1]:out_of_borders_w()==true) then cells_shift_w=cells_shift_w-1; else break; end end end if(cmy&gt;=0) then for i=cells_h,1,-1 do if(cells[1][i]:out_of_borders_h()==true) then --[[cells[1][i].contents.rotation=45; dfd=true;]] cells_shift_h=cells_shift_h+1; else break; end end --return; else for i=1,cells_h,1 do if(cells[1][i]:out_of_borders_h()==true) then cells_shift_h=cells_shift_h-1; else break; end end end --print("~",cells_shift_w,cells_shift_h); local stx,finx,sty,finy=1,cells_shift_w,1,cells_shift_h; if(cmx&lt;0) then stx=cells_w+cells_shift_w; finx=cells_w; end if(cmy&lt;0) then sty=cells_h+cells_shift_h; finy=cells_h; end for i=stx,finx,1 do for j=1,cells_h,1 do if(cells[i][j]) then cells[i][j]:destroy(); cells[i][j]=nil; end end end for i=1,cells_w,1 do for j=sty,finy,1 do if(cells[i][j]) then cells[i][j]:destroy(); cells[i][j]=nil; end end end stx,finx,sty,finy=cells_w-cells_shift_w-1,1,cells_h-cells_shift_h-1,1; local itx,ity=-1,-1; if(cmx&gt;=0) then stx=cells_shift_w+1; finx=cells_w; itx=1; print(stx,finx); end if(cmy&gt;=0) then sty=cells_shift_h+1; finy=cells_h; ity=1; end for i=stx,finx,itx do for j=1,cells_h,1 do if(cells_shift_w~=0) then if(j==1) then print(i,1,"to",i-cells_shift_w,1); end cells[i-cells_shift_w][j]=cells[i][j]; cells[i-cells_shift_w][j]=cells[i-cells_shift_w][j].reset_metatable(cells[i][j]); print("++",cells[i-cells_shift_w][j].contents.width); cells[i][j]:destroy(); cells[i][j]=nil; if(j==1) then print(i-cells_shift_w,1,"width is",cells[i-cells_shift_w][1].contents.width); if(i==7) then cells[6][1].debug=true; print("debug is set"); end end end end end for i=1,cells_w,1 do for j=sty,finy,ity do if(cells_shift_h~=0) then print("?this?",i,j); cells[i][j-cells_shift_h]=cells[i][j]; cells[i][j]:destroy(); cells[i][j]=nil; end end end for i=1,cells_w,1 do for j=1,cells_h,1 do if(cells[i][j]==nil) then print("*new",i,j); cells[i][j]=PCell.new(C.LANDSCAPE_DICTIONARY(nil,1),(i-1)*C.LANDSCAPE_CELL_W+C.LANDSCAPE_CELL_W/2-wshift-camera:getX(),(j-1)*C.LANDSCAPE_CELL_H+C.LANDSCAPE_CELL_H/2-hshift-camera:getY()); end end end end local function stage_main_frame() print("START NOW",6,1,"width is",cells[6][1].contents.width); local old_camera_x,old_camera_y=camera._view.x,camera._view.y; if(dfd==false) then --print("&amp;"); camera._view.x=camera._view.x-stage_frames; end local cmx,cmy=-(camera:getX()-old_camera_x),-(camera:getY()-old_camera_y); manage_cells(cmx,cmy); stage_frames=stage_frames+1; print("NOW",6,1,"width is",cells[6][1].contents.width); return function(event) end end -- Called when the scene's view does not exist: function scene:createScene( event ) local group = self.view end -- Called immediately after scene has moved onscreen: function control_player(event) car1:get_touch(event); end function scene:enterScene( event ) camera:newLayer("land",1); camera:newLayer("bipeds",1); camera:newLayer("cars",1); i=1; while((i-1)*C.LANDSCAPE_CELL_W-C.LANDSCAPE_CELL_W/2-wshift&lt;=C.SCREEN_W) do j=1; cells[i]={}; while((j-1)*C.LANDSCAPE_CELL_H-C.LANDSCAPE_CELL_H/2-hshift&lt;=C.SCREEN_H) do cells[i][j]=PCell.new(C.LANDSCAPE_DICTIONARY(nil,1),(i-1)*C.LANDSCAPE_CELL_W+C.LANDSCAPE_CELL_W/2-wshift-camera:getX(),(j-1)*C.LANDSCAPE_CELL_H+C.LANDSCAPE_CELL_H/2-hshift-camera:getY()); j=j+1; end i=i+1; end cells_w,cells_h=#cells,#cells[1]; local group = self.view physics.start(); physics.setPositionIterations( 1 ) if(events_added==false) then events_added=true; Runtime:addEventListener("touch",control_player); Runtime:addEventListener("enterFrame",stage_main_frame); end end -- Called when scene is about to move offscreen: function scene:exitScene( event ) local group = self.view physics.stop() end -- If scene's view is removed, scene:destroyScene() will be called just prior to: function scene:destroyScene( event ) local group = self.view package.loaded[physics] = nil physics = nil end ----------------------------------------------------------------------------------------- -- END OF YOUR IMPLEMENTATION ----------------------------------------------------------------------------------------- -- "createScene" event is dispatched if scene's view does not exist scene:addEventListener( "createScene", scene ) -- "enterScene" event is dispatched whenever scene transition has finished scene:addEventListener( "enterScene", scene ) -- "exitScene" event is dispatched whenever before next scene's transition begins scene:addEventListener( "exitScene", scene ) -- "destroyScene" event is dispatched before view is unloaded, which can be -- automatically unloaded in low memory situations, or explicitly via a call to -- storyboard.purgeScene() or storyboard.removeScene(). scene:addEventListener( "destroyScene", scene ) ----------------------------------------------------------------------------------------- return scene </code></pre> <p>.</p> <pre><code>local TCell={}; local cell_mt = { __index=TCell }; function TCell.new(_contents_name,_x,_y) --print(camera.x); if(_x==nil) then _x=0; end if(_y==nil) then _y=0; end camera:newLayer( "abacaba", 1 ); local ncell= { contents_name=_contents_name; contents; sequence_data; sheet_data; debug=false; --[[main_frame; main_frame_handler=function(self) main_frame=function(event) if(self.contents.x+self.contents.width/2&lt;0 or self.contents.y+self.contents.height/2&lt;0 or self.contents.x-self.contents.width/2&gt;C.SCREEN_W or self.contents.y-self.contents.height/2&gt;C.SCREEN_H) then --self:destroy(); end end return main_frame; end;]] clear=function(self) if(self.debug==true) then print("CLEAR!!!!!!!!!!!!!!!!!!!!!!!!!!!!\n\n\n\n\n"); end --print(self.contents); self.contents:removeSelf(); camera:removeObject("land",self.contents); end; show=function(self,_contents_name,__x,__y) if(self.debug==true) then print("SHOW!!!!!!!!!!!!!!!!!!!!!!!!!!!!\n\n\n\n\n"); end self.contents_name=_contents_name; if(self.contents_name~=C.EMPTY_IMAGE) then self:set_sequence_data(); end if(self.contents_name~=C.EMPTY_IMAGE) then self.sheet_data=graphics.newImageSheet(self.contents_name,C.LANDSCAPE_SHEET_DATA); self.contents=display.newSprite(self.sheet_data,self.sequence_data); else self.contents=display.newImageRect(C.EMPTY_IMAGE,C.LANDSCAPE_CELL_W,C.LANDSCAPE_CELL_H,true); self.sequence_data=nil; end self.contents.x=__x; self.contents.y=__y; camera:addObject("land",self.contents); end; out_of_borders_w=function(self) --print(self.contents.width); return self.contents.x+self.contents.width/2-camera:getX()&lt;C.LANDSCAPE_CELLS_LEFT_BORDER-C.LANDSCAPE_CELL_W or self.contents.x-self.contents.width/2-camera:getX()&gt;C.LANDSCAPE_CELLS_RIGHT_BORDER+C.LANDSCAPE_CELL_W; end; out_of_borders_h=function(self) return self.contents.y+self.contents.height/2-camera:getY()&lt;C.LANDSCAPE_CELLS_UPPER_BORDER-C.LANDSCAPE_CELL_H or self.contents.y-self.contents.height/2-camera:getY()&gt;C.LANDSCAPE_CELLS_LOWER_BORDER+C.LANDSCAPE_CELL_H; end; reset_metatable=function(target) return setmetatable(target,cell_mt); end; set_sequence_data=function(self) local px=math.floor(((_x)%C.LANDSCAPE_SHEET_DATA.sheetContentWidth)/C.LANDSCAPE_SHEET_DATA.width)+1; local py=math.floor(((_y)%C.LANDSCAPE_SHEET_DATA.sheetContentHeight)/C.LANDSCAPE_SHEET_DATA.height)+1; self.sequence_data= { { name = "only", start=C.LANDSCAPE_SHEET_DATA.sheetContentWidth/C.LANDSCAPE_SHEET_DATA.width*(py-1)+px, count=1 } }; end; destroy=function(self) --Runtime:removeEventListener("enterFrame",self.main_frame); --Runtime:removeEventListener("enterFrame",self.main_frame_handler); self:clear(); if(index~=nil) then --destroy_cell(index); end end }; function ncell:setup() self:show(self.contents_name,_x,_y); end ncell:setup(); return setmetatable(ncell,cell_mt); end return TCell; </code></pre>
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    1. PO
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      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USCommunity
    1. USuser2136963
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      1. LTLinked
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      1. LTLinked
    1. This table or related slice is empty.
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      1. POObject assignment Lua
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
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      1. USuser2136963
      1. VTFavorite
    3. VO
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      1. USuser2136963
      1. VTBountyStart
    1. COThere is mismatched `[`
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      1. UShjpotter92
    2. COCorrected. It's an example. The code looks like: cells[i-cells_shift_w][j]=cells[i][j];
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      1. POObject assignment Lua
      1. USuser2136963
    3. COAre you sure that `i-cells_shift_w`, `i` and `j` always point to valid keys?
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      1. USMartin Ender
 

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