Merge pull request #556 from jstepien/random-srand

Random#srand

spec/tags/core/random/new_tags.txt

@@ -1,6 +1,4 @@
 fails:Random.new uses a random seed value if none is supplied
-fails:Random.new accepts an Integer seed value as an argument
-fails:Random.new accepts (and truncates) a Float seed value as an argument
 fails:Random.new accepts (and converts to Integer) a Rational seed value as an argument
 fails:Random.new accepts (and converts to Integer) a Complex (without imaginary part) seed value as an argument
 fails:Random.new raises a RangeError if passed a Complex (with imaginary part) seed value as an argument

spec/tags/core/random/seed_tags.txt

@@ -1,5 +1 @@
-fails:Random#seed returns an Integer
-fails:Random#seed returns an arbitrary seed if the constructor was called without arguments
-fails:Random#seed returns the same generated seed when repeatedly called on the same object
-fails:Random#seed returns the seed given in the constructor
 fails:Random#seed returns the given seed coerced with #to_int

topaz/modules/kernel.py

@@ -16,6 +16,7 @@
 from topaz.objects.stringobject import W_StringObject
 from topaz.objects.classobject import W_ClassObject
 from topaz.objects.moduleobject import W_ModuleObject
+from topaz.objects.randomobject import W_RandomObject
 
 
 class Kernel(Module):
@@ -381,3 +382,9 @@ def method_catch(self, space, name, block):
                 if e.name == name:
                     return e.w_value
                 raise
+
+    @moduledef.method("srand")
+    def method_srand(self, space, w_seed=None):
+        random_class = space.getclassfor(W_RandomObject)
+        default = space.find_const(random_class, "DEFAULT")
+        return default.srand(space, w_seed)

topaz/objects/randomobject.py

@@ -1,3 +1,6 @@
+import os
+import time
+
 from rpython.rlib.rrandom import Random
 
 from topaz.module import ClassDef
@@ -11,6 +14,7 @@ class W_RandomObject(W_Object):
 
     def __init__(self, space, seed=0, klass=None):
         W_Object.__init__(self, space, klass)
+        self.w_seed = None
         self.random = Random(abs(seed))
 
     @classdef.setup_class
@@ -24,16 +28,25 @@ def method_allocate(self, space, seed=0):
 
     @classdef.method("initialize")
     def method_initialize(self, space, w_seed=None):
-        pass
+        self.srand(space, w_seed)
 
-    @classdef.method("srand")
-    def method_srand(self, space, args_w):
-        self.random = Random()
+    @classdef.method("seed")
+    def method_seed(self, space):
+        return self.w_seed
 
-    @classdef.singleton_method("srand")
-    def method_singleton_srand(self, space, args_w):
-        default = space.find_const(self, "DEFAULT")
-        return space.send(default, space.newsymbol("srand"), args_w)
+    def srand(self, space, seed=None):
+        previous_seed = self.w_seed
+        if seed is None:
+            seed = self._generate_seed()
+        else:
+            seed = Coerce.int(space, seed)
+        self.w_seed = space.newint(seed)
+        if previous_seed is None:
+            value = space.newfloat(self.random.random())
+        else:
+            value = previous_seed
+        self.random = Random(abs(seed))
+        return value
 
     @classdef.method("rand")
     def method_rand(self, space, w_max=None):
@@ -79,3 +92,13 @@ def _rand_int(self, space, integer):
             raise space.error(space.w_ArgumentError, "invalid argument")
         else:
             return space.newint(int(random * max))
+
+    def _generate_seed(self):
+        seed = 0
+        if os.access('/dev/urandom', os.R_OK):
+            file = os.open('/dev/urandom', os.R_OK, 0644)
+            bytes = os.read(file, 4)
+            os.close(file)
+            for b in bytes:
+                seed = seed * 0xff + ord(b)
+        return seed + int(time.time()) + os.getpid()