From: Eric Hodel <drbrain@...7.net>
Date: 2004-11-15T06:04:57+09:00
Subject: Re: assert

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Michael Neumann (mneumann@ntecs.de) wrote:

> On Sun, Nov 14, 2004 at 01:20:49AM +0900, Gavin Sinclair wrote:
> > On Sunday, November 14, 2004, 2:48:24 AM, Florian wrote:
> >=20
> > > Gavin Sinclair wrote:
> >=20
> > >>>>>I have thought about changing the name to "assume" so it can be in=
cluded
> > >>>>>in dev-utils, but I'm not sure if that name is better.
> > >>>I think that would be way too much magic. I'd expect the method to j=
ust
> > >>>take a block.
> > >>=20
> > >> Why a block?  The breakpoint code uses Binding.of_caller anyway, so a
> > >> block is not needed for evaluation.  I don't see any other reason,
> > >> technical or stylistic, why a block should be preferred.
> >=20
> > > Using strings for code is a bit ugly. We have blocks in Ruby, why not
> > > use them? Using a String also causes a bit of escaping trouble (I know
> > > this can be worked around via the %{} or <<-END syntax, but I still=
=20
> > > think blocks are clearer than that.)
> >=20
> > Agreed, but you can print strings.  You can't print blocks.  See
> > below.
>=20
> Hm, has someone tried ParseTree
> (http://www.zenspider.com/ZSS/Products/ParseTree/) to print out blocks?
>=20
> Would be really great if that works.
>=20
>   trace { x + y }           #=3D> x+y =3D 5=20
>   assert { x + y =3D=3D 0 }     #=3D> assertion 'x+y=3D=3D0' failed...
>=20
> Uhm, seems that's only possible to dump methods in classes, not
> arbitrary code. But maybe, it's possible.

$ parse_tree_show
class Test
def test
trace { x + y }
assert { x + y =3D=3D 0 }
end
end
[[:defn,
  "test",
  [:scope,
   [:block,
    [:args],
    [:iter,
     [:fcall, "trace"],
     nil,
     [:call, [:vcall, "x"], "+", [:array, [:vcall, "y"]]]],
    [:iter,
     [:fcall, "assert"],
     nil,
     [:call,
      [:call, [:vcall, "x"], "+", [:array, [:vcall, "y"]]],
      "=3D=3D",
      [:array, [:lit, 0]]]]]]]]

It is pretty easy to walk that tree to find the [:iter, [:fcall,
"trace"], ...] or "assert" and then generate some reasonable english
phrase from it.

You could pull and walk the tree on failures to the assertion you wanted
to generate a comment for...

--=20
Eric Hodel - drbrain@segment7.net - http://segment7.net
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