Dear Khadija,
OS.rand actually generates *pseudo-random* numbers. It is common practice
to initialize such a pseudo-random number generator with a new seed at every
run, typically the current time.
You can do this by calling {OS.srand 0} at the beginning of your program.
Subsequent calls to OS.rand will look more random ;-)
Cheers,
Raphael
On Wed, Sep 8, 2010 at 11:02 AM, Khadija EL MAHRSI <
[email protected]> wrote:
> Hello,
> I tried both methods and they worked but I just wanted to know if the
> values generated by OS.rand are always the same or is there something I'm
> missing.
> OS.rand is supposed to generate random numbers each time but no matter how
> many times I run "main" I always get the same values. I tried recompiling
> and ran "main" again but I got the same values. Is this normal?
>
> Thanks
>
> 2010/9/7 Wolfgang Meyer <[email protected]>
>
> Hi,
>> do you want the OS function to be executed on the site where MyClass
>> is running or locally on the original site?
>> For OS.rand this does not really matter so much, but if you execute,
>> for example, OS.unlink, then it is very important.
>>
>> If you want to execute the code locally on the original site, you
>> could create a kind of "stationary procedure" for OS.rand. There is
>> actually a (undocumented?) system module "Service" for this. Your
>> GrandParent class would look this:
>>
>> functor
>> import
>> OS
>> Service
>> export
>> grandParent:GrandParent
>> define
>> RandService = {Service.synchronous.newFun OS.rand}
>>
>> class GrandParent
>> feat
>> a
>> b
>> c
>> d
>>
>> meth init(A)
>> self.a=A
>> self.b=78
>> self.d={RandService}
>> end
>> %...
>> end
>> end
>>
>>
>> If, on the other hand, the OS function should be executed on the
>> remote site, where the object is living, then you need to link the
>> functor with the class definition on the remote site such that the
>> remote version of OS is used.You can do this with a modified version
>> of CreateRemoteStationaryObject:
>> ------
>> ...
>> fun {CreateRemoteStationaryObject ModuleURL Feat Init RM}
>> ClassModule = {RM link(url:ModuleURL $)}
>> functor RemoteCode
>> export result:Result
>> define
>> Result = try {NewStat ClassModule.Feat Init}
>> catch E then
>> {Value.failed E}
>> end
>> end
>> AppliedFunctor = {RM apply(RemoteCode $)}
>> in
>> AppliedFunctor.result
>> end
>>
>> RM = {New Remote.manager init(host:localhost)}
>>
>> RemoteObject = {CreateRemoteStationaryObject 'MyClasses.ozf' parent
>> init(7) RM}
>> RemoteObject1 = {CreateRemoteStationaryObject 'MyClasses.ozf' child
>> init(9) RM}
>>
>> --------
>> Instead of a class, the function now takes the URL of a functor
>> ('MyClasses.ozf') and the feature of the functor where the class is
>> defined (parent or child).
>> I have also moved the creation of the Remote.manager out of the
>> function because otherwise a new Oz process is created for every
>> object.
>> To make this version of CreateRemoteStationaryObject work in a real
>> distributed application, you have to copy the compiled modules (*.ozf
>> files) to the remote site. As long as you only use localhost, that is
>> not necessary.
>>
>> Hope this helps,
>> Wolfgang
>>
>>
>>
>> On Mon, Sep 6, 2010 at 10:25 AM, Khadija EL MAHRSI
>> <[email protected]> wrote:
>> > Hello,
>> > using this information I wanted to do the following:
>> > Create a stationary instance of a class (let's call it MyClass) on a
>> remote
>> > site (thanks to the code you've given me earlier in another topic:
>> "Sending
>> > classes to a remote site"). This is the instance creation code line:
>> > T={CreateRemoteStationaryObject MyClass init()}
>> > This class' init method uses an init method from another class
>> (MySupClass)
>> > from which it also inherits its features (class MyClass from
>> MySupClass).
>> > In this class' init method (MySupClass) I want to use OS.something
>> (OS.rand
>> > for example) to fill this class' features. Can I do this?
>> >
>> > Thanks, I really appreciate the help you're always willing to offer.
>> >
>> > 2010/9/5 Wolfgang Meyer <[email protected]>
>> >>
>> >> Hi,
>> >>
>> >> to use a sited module, you have to make sure that you use a local
>> >> module instance, i.e. a version of OS that has been linked on the
>> >> running site.
>> >> To achieve this, code is packaged in a functor with its dependencies.
>> >> An example:
>> >> This code won't work because it uses a remote "OS":
>> >>
>> >> declare
>> >> functor RemoteCode
>> >> export R
>> >> define
>> >> R = {OS.rand}
>> >> end
>> >>
>> >> RM = {New Remote.manager init}
>> >> AF = {RM apply(RemoteCode $)}
>> >> {RM close}
>> >> {Show AF.r}
>> >>
>> >>
>> >> But this code will work, because it uses a locally imported "OS":
>> >>
>> >> declare
>> >> functor RemoteCode
>> >> import OS %% This line is the only difference
>> >> export R
>> >> define
>> >> R = {OS.rand}
>> >> end
>> >>
>> >> RM = {New Remote.manager init}
>> >> AF = {RM apply(RemoteCode $)}
>> >> {RM close}
>> >> {Show AF.r}
>> >>
>> >> So you have to package the class in a functor and make sure that this
>> >> functor is applied or linked on the remote site where the class
>> >> instance is running.
>> >>
>> >> Hope this helps,
>> >> Wolfgang
>> >>
>> >>
>> >> On Sun, Sep 5, 2010 at 12:58 PM, Khadija EL MAHRSI
>> >> <[email protected]> wrote:
>> >> > Hello,
>> >> > Correct me if I'm wrong, after some research I came to the conclusion
>> >> > that
>> >> > since OS is sited it is not possible to achieve the idea I had so
>> >> > instead I
>> >> > will have the result of OS.something passed to this class as
>> parameter
>> >> > through a method.
>> >> > Thanks.
>> >> >
>> >> > 2010/9/4 Khadija EL MAHRSI <[email protected]>
>> >> >>
>> >> >> Hello,
>> >> >> I was wondering if it is possible to have a class running on a
>> remote
>> >> >> site
>> >> >> execute OS.(something) and put the result in a feature of this class
>> >> >> (like
>> >> >> self.x=OS.rand for example).
>> >> >> Thanks
>> >> >
>> >> >
>> >> >
>> >> >
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