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From: Richard Jones <rjones@orchestream.com>
Subject: Re: Software landmines (loops)
Date: 1998/09/01
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Date: 1998-09-01T00:00:00+00:00
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Robert Martin <rmartin@oma.com> wrote:

> Mattias Lundstr�m wrote in message <35EAB5B1.1DA1986B@ehpt.com>...

> It's not so much a matter of being harder to read and understand.  Rather it
> is that there is no good place to make certain kinds of changes to the code.

> For example,  let's say that we had to make a change that forced us to open
> and close a file that the body of the loop needed to read.  Then:

> 1. Flag solution
> File* f = fopen(...);
> while( ... && retval == OK ) {
>   ...
>   if( ... )
>     retval = NOT_OK;
> }
> fclose(f);
> return retval;

> vs

> 2. Multiple exits
> File* f = fopen(...);
> while( ... ) {
>   ...
>   if( ... ){
>     fclose(f);
>     return NOT_OK;
>   }
> }
> fclose(f);
> return OK;

Both of you miss the point that exceptions solve this problem
neatly and naturally, i.e. in some sort of bastardized
Java/C++ hybrid you might write:

    File f ("name", File::OpenReadOnly);
    while (...) {

      if (error_condition) throw new ErrorException;
    }
    return;

Rich.

-- 
Richard Jones rjones@orchestream.com Tel: +44 171 598 7557 Fax: 460 4461
Orchestream Ltd.  125 Old Brompton Rd. London SW7 3RP PGP: www.four11.com
"boredom ... one of the most overrated emotions ... the sky is made
of bubbles ..."   Original message content Copyright � 1998