[Zope-dev] Re: Using DTML is too difficult (was: [Zope] DTML Syntax contd. + rant)

[Martijn Faassen]

Hi people,

Ah, you're replying to my rant here. :)

Rik Hoekstra wrote:
[snip] 
> I _really_ like Zope, 

me too, no question.

> but I am afraid I have to agree with you. 

I agree with myself too. :)

> I'll add
> some more rant. I believe it's important to stress that this is _not_ meant
> as criticism per se, but only to point out what even for people who have
> used ZOpe for almost a year are major flaws in its usability. And I can vote
> for Martijn, that he's not stupid; I myself have the excuse of not coming
> from a computer science background, but still I rabble on.

Thanks for your vote of non-stupidity. :)
 
> > Philosophical end rant:
> >
> > If I ever get the time I'd be tempted to work on a DTML 'cleanup'
> > project. DTML is currently *far* too much like Perl and not enough like
> > Python. *some* easy things are very easy, but as a consequence some
> > other easy things become far too hard, or at least look far too
> > complicated. You can spell the same thing in too many ways. The
> > community encourages and praises additions for convenience (like the
> > 'default' option, or the new extended &entity; syntax) but as a result
> > DTML loses its conceptual integrity. It becomes too big and not easy to
> > understand.
> >
> > I understand the argument that DTML shouldn't be used for complicated
> > purposes, and that you should use Python. This is fine and good, but in
> > practice people *do* use DTML for complicated purposes. ZClasses in fact
> > encourage this.
> 
> The point is that it's not always clear when things are complicated. And
> using python for complicated tasks is not exactly a piece of cake either,
> for a number of reasons.
> - writing products in python is complicated and mostly not worth it

Though this is getting easier in the newer Zopes. Or I'm learning more
about it.

I highly recommend the 'Boring HOWTO' in this regard, by the way. 

> - writing python base classes for ZClasses is easier, but using them in the
> Z framework requires  quite a bit of understanding of ZClasses and the Zope
> framework in general

Yes, this is pretty easy, but (as Amos remarked in his slides),
distribution is currently difficult. Also if something goes wrong you
can end up with objects in weird states which you can't delete.

And it's true they could probably be simplified (or the documentation
improved) so that still less understanding about Zope's inner details is
necessary.

> - External methods are much easier, but they have their own disadvantages:
>      (1) it is less than obvious how they interact with the dtml
> methods/namespace they are called from
>      (2) they are not easily transported to another machine, because you
> need physical access to the
>          filesystem for that (I understand that that's the only way)

Though you can say the same for Products and ZClasses for Python base
classes.

Python Methods are cool. I haven't played a lot with them as I'm working
on a production site, but I intend to play with them more.
 
> >
> > DTML should be more like Python.
> 
> Yes
> 
> > Luckily the Zope framework does allow
> > new objects to be plugged in using something else than DTML, so not all
> > hope is lost. :)
> 
> But it should be easier to use this stuff (do I hear the word developer
> documentation??? uuummm)

It's not only documentation though. The 'with' issue that caused me to
rant is simply not consistent enough. There are more places in DTML
where it is like this. The _[_['sequence-item']] style constructions are
also obfuscatory.
 
> > Feedback on this rant would be appreciated.
> 
> My 2 cents.

Thanks!
 
Regards,

Martijn