From: Jason Roelofs <jameskilton@...>
Date: 2007-06-05T05:53:04+09:00
Subject: Re: Help needed: Dynamically create a Proc from a String and evaluate it

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Don't you mean

g.call(1.0, 2, 5) ?

You have to do proc.call, they aren't regular methods.

Jason

On 6/4/07, Axel Etzold <AEtzold@gmx.de> wrote:
>
> Dear Brian,
>
> thank you for responding.
> However, I still haven't solved my problem.
> So, following one of your suggestions, I get:
>
> p 'function-text'
> p f  =3D> "eval('proc{|c,x,k| c*Math.exp(x/k) }')"
> g=3Deval(f)=3D> #<Proc:0x00002b56c768ef68@(eval):1>
>
> p g(1.0).call(2,5)  =3D> undefined function or variable 'g'
>
> I can't get to use the proc I just created.. Why not ?
>
> Thank you,
> Axel
>
>
>
> -------- Original-Nachricht --------
> Datum: Tue, 5 Jun 2007 04:55:57 +0900
> Von: Brian Candler <B.Candler@pobox.com>
> An: ruby-talk@ruby-lang.org
> Betreff: Re: Help needed: Dynamically create a Proc from a String and
> evaluate it
>
> > On Tue, Jun 05, 2007 at 04:18:58AM +0900, Axel Etzold wrote:
> > > I need help in dynamically creating a Proc from  a String like, say,
> > >
> > >     a=3D'f(x)=3Dc*exp(x/k)',
> >
> > If you're passing in c and k each time, then
> >
> > b =3D eval("proc{|c,x,k| c*Math.exp(x/k) }")
> > puts b.call(5.0, 2.0, 1.0)
> >
> > This means you only call eval once, to create the proc object, then you
> > can
> > call it as many times as you like.
> >
> > If c and k really are constants then you can substitute them in to the
> > proc
> > definition:
> >
> > c =3D 5
> > k =3D 2
> > a =3D eval("proc { |x| #{c}*Math.exp(x/#{k}) }")
> > puts a.call(3)
> >
> > or you can use the closure property to bind the local variables
> directly:
> >
> > c =3D 5
> > k =3D 2
> > a =3D eval("proc { |x| c*Math.exp(x/k) }")
> > puts a.call(3)
> >
> > Brian.
>
> --
> Psssst! Schon vom neuen GMX MultiMessenger geh=F6rt?
> Der kanns mit allen: http://www.gmx.net/de/go/multimessenger
>
>

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