Differences

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--- lua:sharedtable [2015/09/28 07:07] – [Shared functions] vodur
+++ lua:sharedtable [2015/09/28 16:36] (current) – vodur
@@ Line 72: / Line 72: @@
     return false
 end
+</code>
+===== Loading shared code =====
+When using shared table to store shared code such as helper functions, a typical way to do this is to put all the functions in a single prog and call this prog from any prog that uses the helper functions. Additionally, it is good practice to insure the code is only loaded once.
+Example using a loaded flag:
+<code lua>
+-- mprog 1234
+if shared.helpers_loaded then return
+function shared.helper1()
+    echo("helper 1 test test test")
+end
+function shared.helper2()
+    echo("helper 2 test test test")
+end
+shared.helpers_loaded=true
+</code>
+<code lua>
+-- mprog 1235
+loadprog(1234)
+shared.helper1()
+</code>
+<code lua>
+-- mprog 1236
+loadprog(1234)
+shared.helper2()
+</code>
+Similar example using a module style:
+<code lua>
+-- mprog 1234
+if shared.module1 then return
+local module1={}
+module1.helper1 = function()
+    echo("helper 1 test test test")
+end
+module1.helper2 =  function()
+    echo("helper 2 test test test")
+end
+shared.module1 = module1
+</code>
+==== Sharing with different prog types ====
+All prog types have access to 'shared' table (mprog/oprog/aprog/rprog). However, if all your shared code is in mprog 1234 (as above example), only mprogs can easily load this code using [[:lua:ch:loadprog|loadprog]]. Loadprog called from oprog can only load oprogs, and similarly with aprog and rprog.
+One strategy to overcome this limitation is to keep all the shared code in an aprog and load it from the different prog types accordingly:
+<code lua>
+-- aprog 1234, shared helper functions for all prog types
+if shared.helpers_loaded then return
+function shared.helper1()
+    echo("helper 1 test test test")
+end
+function shared.helper2()
+    echo("helper 2 test test test")
+end
+shared.helpers_loaded=true
+</code>
+<code lua>
+-- aprog 1235
+loadprog(1234)
+shared.helper1()
+shared.helper2()
+</code>
+<code lua>
+-- mprog 1234
+mob.proto.area:loadprog(1234)
+shared.helper1()
+shared.helper2()
+</code>
+<code lua>
+-- oprog 1234
+obj.proto.area:loadprog(1234)
+shared.helper1()
+shared.helper2()
+</code>
+<code lua>
+-- rprog 1234
+room.area:loadprog(1234)
+shared.helper1()
+shared.helper2()
+</code>
+Using '**[[:lua:loadscriptfunction|loadscript]]**' is also an option:
+<code lua>
+-- helpers_example.lua, shared helper functions for all prog types
+if shared.helpers_loaded then return
+function shared.helper1()
+    echo("helper 1 test test test")
+end
+function shared.helper2()
+    echo("helper 2 test test test")
+end
+shared.helpers_loaded=true
+</code>
+<code lua>
+-- aprog 1235
+loadscript('vodur','helpers_example')
+shared.helper1()
+shared.helper2()
+</code>
+<code lua>
+-- mprog 1234
+loadscript('vodur','helpers_example')
+shared.helper1()
+shared.helper2()
+</code>
+<code lua>
+-- oprog 1234
+loadscript('vodur','helpers_example')
+shared.helper1()
+shared.helper2()
+</code>
+<code lua>
+-- rprog 1234
+loadscript('vodur','helpers_example')
+shared.helper1()
+shared.helper2()
 </code>