From: Sean Middleditch <elanthis@...>
Date: 2002-04-06T12:28:08+09:00
Subject: Re: Is eval a code/design smell?

On Fri, 2002-04-05 at 05:26, Tobias Reif wrote:
> Sean Middleditch wrote:
> 
> > If you are
> > dynamically generating code, you are probably doing things in a much
> > uglier way than you should be
> 
> 
> I don't see his.
> 
> > (and Ruby should/does provide the faster,
> > prettier ways of doing things).
> 
> 
> For example?
> 
> If I generate a lib from a schema, this takes some time for large schemas.
> So I don't do this every time I use the lib, but simple load the 
> generated lib; fast.
> No schema required anymore(in which case I would happily use eval.)
> 
> What alternative would you suggest here?

If eval() is running faster than your schema->lib functions, then I
would simply say your functions are too slow.  ^,^

I still don't see why Ruby shouldn't provide methods for quickly,
easily, and powerfully constructing classes at runtime with sending
untrustable content to the parsing engine.  Because, I can just imagine
someone downloading a schema from the web that has an embedded
kernel.system('rm -rf $HOME/') - if you provide a schema in non-code
format, that can be parsed in a safe manner that checks for this stuff.

If you need to dump arbitrary objects (that might be valid to have a
command to delete your home directory) it would probably be cleaner
anyways to be able to serialize the bytecode/tree nodes, and store
those; it would load even faster, and lend itself easier to progessive
execution (if you're into that kind of masochistic activity... ~,^)

> 
> 
> Tobi
> 
> 
> -- 
> Neither simple nor complex matters are to be complicated.
>