Re: Re: [patch rfc 1/3] xen arch header rework.

[Julian Davison <julian-xen_devel@tech.cbhs.school.nz>]

Steven Rostedt wrote:
> Julian Davison wrote:
>> Gerd Hoffmann wrote:
>>> I don't think adding perl as build dependency is a big problem, almost
>>> everyone has it on the machine anyway.  Try "rpm -e perl" on any linux
>>> distro and watch the error message with the long list of stuff which
>>> depends on perl.
>>
>> While I realise this is drifting from the topic somewhat,
>> if I could just say:
>> jade:~# rpm -e perl
>> rpm: To install rpm packages on Debian systems, use alien. See 
>> README.Debian.
>> error: cannot open Packages index using db3 - No such file or 
>> directory (2)
>> error: cannot open /var/lib/rpm/packages.rpm
>>
>> Perl is most certainly on that system, but 'perl is everywhere'
>> is a little like 'rpm is everywhere'.
> 
> OK, then try this:
> 
> # apt-get remove perl
> Reading package lists... Done
> Building dependency tree... Done
> The following extra packages will be installed:
>   gaim-data gimp-data wesnoth-data
> Recommended packages:
>   wesnoth-utbs wesnoth-ttb wesnoth-tsg
> The following packages will be REMOVED
[snip]
> Need to get 34.2MB of archives.
> After unpacking 1837MB disk space will be freed.
> Do you want to continue [Y/n]? n
> Abort.

jade:~# apt-get remove perl
Reading Package Lists... Done
Building Dependency Tree... Done
The following packages will be REMOVED:
   alien build-essential debhelper defoma dpkg-dev ethereal fontconfig
   intltool-debian libcompress-zlib-perl libfontconfig1 libft-perl
   libgtk2.0-0 libgtk2.0-bin libgtk2.0-common libmail-sendmail-perl
   libpango1.0-0 libpango1.0-common libxft2 ntp ntp-server ntp-simple
   perl perl-doc perl-modules po-debconf rpm ttf-bitstream-vera xterm
0 upgraded, 0 newly installed, 28 to remove and 0 not upgraded.
Need to get 0B of archives.
After unpacking 59.8MB disk space will be freed.
Do you want to continue? [Y/n] n
Abort.


Of course the exact list all depends on what the box does :)
(Incidentally, those that read carefully may have noticed 'rpm'
  now appears to be in the list, how bizarre)

> So, Gerd's example of using rpm was bad, and I wouldn't compare having 
> perl to having rpm.

In the grand scheme of things neither would I. (Hence the 'little
like' :) I was aiming at highlighting the fact that what was
ultimately happening here (IMHO) was broad assumptions/assertions
were being made based on what's true in the individuals surrounding
environment.

>>> Wrt. readability of the scripts:  That is IMO more a matter of the
>>> programming style than of the programming language.  Sure you can easily
>>> write unreadable perl code, but you don't have to.  And you better
>>> shouldn't, just in case you have to touch the scripts again one year 
>>> later.
>>
>> I spend far more time with python than I do perl, I confess,
>> however one of my colleagues spends no time with either and
>> has far less trouble understanding python than perl.
>> In terms of novice-readability perl has a whole bunch of
>> (really useful) line noise constructs. =~, say.
> 
> But that is an extremely more powerful tool than anything in python.

Undoubtedly.

>> In many cases having a tool in an 'odd' language is better than
>> no tool at all, but in general the fewer dependencies the better.
>>
>>
> 
> I find python annoying to work with.  Is it spaces or tabs?

Spaces :)

> 
> if a:
>   <do something>
>   if b:
>     <do this>
>     if c:
>        <do that>
>        if d:
>          <do another>
>          if e:
>            <do whatever>
>            <and more>
>            <and that>
>            <and here>
>            <and there>
>     if f:
>       <do this too>
>       if g:
>          <do that as well>
>   <Now what if am I on???>
> 
> 
> Using columns instead of blocks has brought me back to the old days on 
> the old IBM Mainframes.  It sometimes gets confusing to know where 
> you're at. And I haven't found emacs or vi helpful in telling you which 
> "if" you are working under. (both easily show which { matches which } ).

I've most definitely got a list of peeves about python too,
don't get me wrong. When I first heard about python I thought
the 'blocks-by-indentation' was completely absurd. But you get
used to it, even if you don't ever like it.

I'm hesitant to say it (as I hate people who say this sort
of thing) but, use something that isn't emacs or vi :)

> But, OK, I like C better than most languages. So if I need something 
> done I usually write it in C.  But if it has to do with string 
> manipulation and file parsing, I'll write it in perl.

Sounds familiar :)

> Yes perl can be obfuscated, and hard to read if someone writes it that 
> way.  But I have written lots of perl scripts where I need to work with 
> them after a year or two, and it's never been a problem with me to 
> understand what I did.  I just write my perl scripts like I write C and 
> it never has been a problem.

Though I was looking at *someone else* working with the code.
If you can't read your own code then there's a fairly serious
problem with the way you write. If someone who has been using
the language for several years can't read your code, that's also
a style problem.
A python expert may well not be able to comprehend perl, while
a perl expert has a far greater chance of comprehending a python
script.

> I picked up perl a lot faster than I picked up python, and I still don't 
> have a strong urge to go the python route.

While I don't mind python (or perl) the primary reason I've
done so much in it is due to the environment here at work.
The intranet is running on Plone/Zope/Python, which leads to
python being a better (and easier) choice than perl.
Which was a point in this discussion that I thought quite
important - the more things that are the same the easier
it is to get a handle on the whole (once you can grasp
a part)

> Anyway, perl vs python is just like emacs vs vi, or gnome vs kde.

Nah, there are lots of things perl's far better suited
for than python (and vice versa).
emacs/vi and gnome/kde arguments are just a bunch of lunatics
that should get on with using the thing instead of evangelising :)

> But just for comparison's sake:
> 
> # apt-get remove python
> Reading package lists... Done
> Building dependency tree... Done
[snip]
> Do you want to continue [Y/n]? n
> Abort.

jade:~# apt-get remove python
Reading Package Lists... Done
Building Dependency Tree... Done
Package python is not installed, so not removed
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.


> No snipping needed :-)

Indeed :)

-- 
Julian Davison
Note: 1) This may have come from an address @cbhs.school.nz
          but isn't necessarily the (or even an) official view
          of Christchurch Boys' High School
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          it will almost certainly be filtered into a mailing list
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