Note there is also srand() method that seeds the generator. The generator therefore needs to be associated with RubyExecutionContext.
Tomas From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Curt Hagenlocher Sent: Sunday, July 06, 2008 11:49 AM To: [email protected] Subject: Re: [Ironruby-core] rand() needs a seed? Something like that, yes, but making it a static member of KernelOps means that we have to pay the construction cost during startup. For a function as infrequently used as "rand", it might be better to initialize it more lazily. From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Johan Danforth Sent: Sunday, July 06, 2008 9:51 AM To: [email protected] Subject: Re: [Ironruby-core] rand() needs a seed? Like this? private static readonly Random rndGen = new Random(); [RubyMethod("rand", RubyMethodAttributes.PrivateInstance)] [RubyMethod("rand", RubyMethodAttributes.PublicSingleton)] public static double Rand(CodeContext/*!*/ context, object self) { lock(rndGen) return rndGen.NextDouble(); } [RubyMethod("rand", RubyMethodAttributes.PrivateInstance)] [RubyMethod("rand", RubyMethodAttributes.PublicSingleton)] public static object Rand(CodeContext/*!*/ context, object self, int limit) { if (limit == 0) return Rand(context, self); lock (rndGen) return RuntimeHelpers.Int32ToObject((int)(rndGen.NextDouble() * (limit - 1))); } [RubyMethod("rand", RubyMethodAttributes.PrivateInstance)] [RubyMethod("rand", RubyMethodAttributes.PublicSingleton)] public static object Rand(CodeContext/*!*/ context, object self, double limit) { if (limit < 1) return Rand(context, self); lock (rndGen) return RuntimeHelpers.Int32ToObject((int)(rndGen.NextDouble() * (limit - 1))); } I put a lock() on each call as well, because I believe the Next-methods aren't thread safe. Works for me. /Johan From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Curt Hagenlocher Sent: den 6 juli 2008 17:16 To: [email protected] Subject: Re: [Ironruby-core] rand() needs a seed? By default, the parameterless constructor of the System.Random class (which is what we're using) uses the system time as the initial seed. Every time you ask for a random number, we create a new Random object, and in a tight loop like yours, they'll probably all get the same seed. We should probably create a single Random object the first time that one is requested and store it in the RubyContext. From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Johan Danforth Sent: Sunday, July 06, 2008 7:28 AM To: [email protected] Subject: [Ironruby-core] rand() needs a seed? I'm a noob Ruby user, but IronRuby behaves different from other Ruby implementations that I've tried, in IronRuby (rev 121) this code: 100.times {p rand(100)} Often returns the same value for (almost) all iterations, like this: 2 2 2 2 2 2 2 2 ...and so on... Works as designed? Need to seed it or something? /Johan
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