1 files changed, 82 insertions, 0 deletions
diff --git a/examples/lurn.pd_lua b/examples/lurn.pd_lua
new file mode 100644
index 0000000..09412f3
--- /dev/null
+++ b/examples/lurn.pd_lua
@@ -0,0 +1,82 @@
+-- urn class: random selection without repetitions.
+-- fbar 2007
+
+-- urn interface:
+
+local urn = {}
+
+function urn.new(size)
+    assert(size > 0, "Error: size of urn must be greater than 0")
+    local t = {size=size, last=size}
+    for i=1,size do
+        t[i] = i
+    end
+    return t
+end
+
+function urn.get(u)
+    if u.last > 0 then
+        local i = math.random(u.last)
+        local res = u[i]
+        u[i] = u[u.last]
+        u.last = u.last - 1
+        return res
+    else
+        return nil
+    end
+end
+
+function urn.reset(u)
+    u.last = u.size
+    for i=1,u.size do
+        u[i] = i
+    end
+end
+
+-- Pd class: 
+
+local M = pd.Class:new():register("lurn")
+
+function M:initialize(name, atoms)
+    if type(atoms[1]) == "number" and atoms[1] >= 1 then
+        self.u = urn.new(math.floor(math.max(atoms[1]), 1))
+    else
+        self.u = urn.new(1)
+    end
+    self.inlets = 2
+    self.outlets = 2 
+    return true
+end
+
+function M:finalize()
+    self.u = nil
+end
+
+function M:in_2_float(f)
+    if f >= 1 then
+        self.u = urn.new(math.floor(f))
+    else
+        self:error("size of urn too small. needs to be 1 at least")
+    end
+end
+
+function M:in_1_clear(atoms)
+    urn.reset(self.u)
+end
+
+function M:in_1_seed(atoms)
+    if type(atoms[1]) == "number" then
+        math.randomseed(atoms[1])
+    else
+        self:error("seed needs a number")
+    end
+end
+
+function M:in_1_bang()
+    local f = urn.get(self.u)
+    if type(f) == "number" then
+        self:outlet(1, "float", {f - 1})
+    else
+        self:outlet(2, "bang", {})
+    end
+end