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From: Philip Haynes <p.haynes@oose.com.au>
Subject: Re: 3GL to Smalltalk metrics
Message-ID: <31A2E56E.6BBC@oose.com.au>
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Date: Wed, 22 May 1996 09:59:10 GMT
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Harvey Lim wrote:
> 
> Does anyone have any idea how to estimate how long it would take to
> rewrite an existing 3GL (COBOL,C) system to Smalltalk.  What factors
> should I consider with respect to the coding only (assuming experienced
> Smalltalk programmers who know the business domain and no functionality
> changes).
> 
> I was thinking of roughly equating 1 section to 1 method, then applying
> some metrics from Lorenz (OO Development Metrics)... but if anyone has
> any real-life experience... that'd be great.
> 
> Thanks in advance.  Either reply to this newsgroup if you think it
> relevant to the masses, or send me an e-mail at harveyl@bcaa.bc.ca.

Capers Jones in an American Programmer article [Oct 94] provides
an estimate of a 3.4 to 1 reduction, over a full development 
lifecycle from C to Smalltalk. This assumes (I believe), 
no infrastructures are used. This is for projects of 1,500 FP in
size, or approximately 580 classes.

In a number of internal studies we have performed, for 
a number of similarly sized C++ & Smalltalk projects size projects 
have shown this report is certainly to approximately 10-20%, although
we have found the relative effort in different phases to be different.

We have found in the coding phase a 4 to 1 productivity difference
is pretty typical. One study for example, where we took a 
prototype written in  Smalltalk & compared the amount of code in the 
prototype, to the equivalent functionality in Basic Like language 
showed a  4 to 1 reduction in code.

I hope this helps.

Regards
Phil Haynes 

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