[plt-scheme] two questions about extensions and 3m under 372

From: Chongkai Zhu (czhu at cs.utah.edu)
Date: Sat May 3 00:40:39 EDT 2008

Neil Van Dyke wrote:
> 1. What experiences have people had moving their existing MzScheme 
> extensions from CGC to 3m?

For me, under CGC, I used to insert MZ_GC_REG and so on manually, but 
later I find out using mzc --xform is much easier.

> 2. What experiences have people had opting to stay with CGC?

AFAIK, there's not too much difference between 300 and 372, other than 
the xform get improved a lot. I managed to carefully re-structure my C 
code to make it work with xform. It might be hard for you, if you 
existing C code doesn't go well with xform. Manually inserting MZ_GC_REG 
and so on is very error prone, just like manually inserting malloc/free. 
And as far as I can tell, such error is hard to detect before 
deployment. I didn't stay with CGC because I knew I have to move on, but 
my result code works with CGC.

My 2 cents,

> Background details follow...
> I'm helping to move a system deployed under PLT v300 to v372.  The 
> system uses multiple in-house MzScheme extensions written in C.  We 
> therefore need to decide whether to use the old CGC or 3m.
> My main concern is the unknown risk that I will make an error in the 
> conversion of the C code to 3m that won't manifest until this system 
> is deployed to customers under 372, which would be very bad.  (Perhaps 
> it's easier to write for 3m from the start, rather than have a 
> different programmer convert after the fact.)
> I don't know the likelihood of error if I work very diligently, nor 
> the likelihood that any such error would be detected before deployment.
> By the way, any eventual move to PLT v4 is not a concern for this 
> system at this time.
> Thanks,
> Neil
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