[prev in list] [next in list] [prev in thread] [next in thread] 

List:       kde-devel
Subject:    Re: The no goto religion
From:       "Robert Knight" <robertknight () gmail ! com>
Date:       2007-08-05 3:09:06
Message-ID: 13ed09c00708042009o696e7efdj3c042df0644598ad () mail ! gmail ! com
[Download RAW message or body]

> His numbers are based on how
> the code would compile.  Not on actual execution in a specific
> architecture.  I don't think that there is any doubt that, in most
> cases, more instructions will result in longer execution time.

I have now read the PDF of the paper you linked to.  It was an
interesting read, thank you for providing the link.

However, I believe that it does not support the theme of your posts.
From the introductory section in which Knuth provides the background
to the debate (page 268):

  "A good programmer
  will not be lulled into complacency by such
  reasoning, he will be wise to look carefully
  at the critical code; but only after that code
  has been identified. It is often a mistake to
  make a priori judgments about what part
  of a program are really critical, since the
  universal experience of programmers who
  have been using measurement tools has been
  that their intuitive guesses fail."

And just before that, the now legendary quote:

> We should forget about small
> efficiencies, say about 97% of the time: pre-
> mature optimization is the root of all evi

Given that most of KDE is essentially sitting atop a big stack of
other libraries, issuing function calls to get things done, the kind
of critical loops that he talks about in the paper are not
common-place.  If you look at parts of the glibc code however, such as
heavily used string processing functions, then you will find them.

Knuth also explicitly advocates readability over micro-optimisation in
what he refers to as the "97%" of the code which is outside the
critical inner loops.

The broad message running through the paper that people should not
become dogmatic or religious about their approach to programming tools
is obviously sensible, but I think would make more sense to a reader
in the context of the on-going discussions which were being held at
the time, several of which are mentioned in the introduction.  The
modern example I can think of is the backlash in a few quarters
against the use of Mono or other high level languages.  Personally I
do not think the rarity of goto in KDE code is a religious or
'dogmatic' choice as the title of your original email implied.
Rather, I believe it is because people have picked up the style of
existing code which for whatever reason tended not to use it often.
In my case neither my programming books, nor my course lectures, nor
existing open source code I work with uses goto in their solutions
often.

In summary, reading this thread has been rather like watching a
journalist stumble into a Fleet Street editor's office in 2007 with
his breaking news and analysis of the Crimean War.   Interesting, but
a couple of days late.



On 05/08/07, Gabriel Anderson <zettablade@gmail.com> wrote:
> Is this guy trolling?
>
> >> Visit http://mail.kde.org/mailman/listinfo/kde-devel#unsub to unsubscribe
> <<
>
 
>> Visit http://mail.kde.org/mailman/listinfo/kde-devel#unsub to unsubscribe <<
[prev in list] [next in list] [prev in thread] [next in thread]