Integrate Ben's section on dollar symbol expansion, add example.

pdlua/tutorial/examples/localsend.pd

@@ -0,0 +1,20 @@
+#N canvas 580 203 398 197 12;
+#X declare -lib pdlua;
+#X obj 240 110 tgl 20 0 empty \$0-onoff empty 17 7 0 10 #dfdfdf #000000
+#000000 1 1;
+#X floatatom 240 144 5 0 0 0 - - -, f 5;
+#X obj 40 120 bng 20 250 50 0 empty empty empty 17 7 0 10 #dfdfdf #000000
+#000000;
+#X text 68 119 <-- click me;
+#X obj 175 19 declare -lib pdlua;
+#X obj 40 154 localsend \$0-onoff;
+#X obj 290 110 tgl 20 0 empty onoff empty 17 7 0 10 #dfdfdf #000000
+#000000 0 1;
+#X floatatom 290 144 5 0 0 0 - - -, f 5;
+#X msg 40 50 sender \\\$0-onoff;
+#X msg 40 80 sender onoff;
+#X connect 0 0 1 0;
+#X connect 2 0 5 0;
+#X connect 6 0 7 0;
+#X connect 8 0 5 0;
+#X connect 9 0 5 0;

pdlua/tutorial/examples/localsend.pd_lua

@@ -0,0 +1,23 @@
+local localsend = pd.Class:new():register("localsend")
+
+function localsend:initialize(sel, atoms)
+   self.inlets = 1
+   -- pass the symbol from the creation argument,
+   -- which gets automatically expanded here
+   self.sender = tostring(atoms[1])
+   return true
+end
+
+function localsend:in_1_sender(x)
+   local sendername = tostring(x[1])
+
+   -- store the original name as argument (like "\$0-foo")
+   self:set_args({sendername})
+
+   -- apply the expanded name with the local id
+   self.sender = self:canvas_realizedollar(sendername)
+end
+
+function localsend:in_1_bang()
+   pd.send(self.sender, "bang", {})
+end