Re: Newbie questions about persistence

On Tue, 2009-09-01 at 16:08 +0100, Thomas Leonard wrote:
> On Fri, 2009-08-28 at 19:15 -0400, Kevin Reid wrote:
> > On Aug 28, 2009, at 10:27, Thomas Leonard wrote:
[...]
> > > Persistence of cycles
> > >
> > > Some cyclic data structures can be persisted, while others can't (is
> > > this a bug?). I haven't worked out what the rule is, but I do have
> > > some examples:
> > ...
> > > 	Serializing [[<***CYCLE***>], [<***CYCLE***>]]...
> > > 	Serialized as de: [def t__0 := [t__0], t__0]
> > > 	# problem: <IndexOutOfBoundsException: not found: t__0>
> > >
> > > This is quite annoying, because a SwissRetainer includes a pointer to
> > > its object, in addition to the pointer in the table for which the
> > > retainer is a key. Therefore, an object containing a single cycle ends
> > > up with the broken double-cycle structure when saved.
> > 
> > This is a bug. Please send versions, test cases, patches, etc.
> 
> A minimal test case is:
> 
> 	def surgeon := <elib:serial.makeSurgeon>.withSrcKit("de: ")
> 	surgeon.unserialize("de: [def t__0 := [t__0], t__0]")
> 
> which gives:
> 
> 	# problem: <IndexOutOfBoundsException: not found: t__0>
> 
> Happens with the current release (0.9.2a) and svn versions of E.

Is there any reason not to unserialize Data-E using e.g.
eParser(s).eval(privilegedScope)?

That avoids this bug, and is about 10x faster, too.

? surgeon.unserialize("[def t__0 := [t__0], t__0]")
# problem: <IndexOutOfBoundsException: not found: t__0>

? eParser("[def t__0 := [t__0], t__0]").eval(safeScope)
# value: [[<***CYCLE***>], [<***CYCLE***>]]


-- 
Dr Thomas Leonard
IT Innovation Centre
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