webgen users - Aug 2008 - stack level too deep - an elusive bug?

I was experimenting with template chains and detected the following 
issue with webgen-0.5.3:

    Generating tree...
    An error has occurred:   stack level too deep

The weird thing is that after deleting `webgen.cache`, website 
compilation is successfully. When `webgen` is run immediately after this 
successful compilation (i.e. without changing any files), the error 
above shows up. After that, *every* compilation will end with this 
error, independent of source files changes.

Deleting `webgen.cache` every time wouldn''t bother me much, but my 
website will have pretty big volume and I estimate computation times of 
up to a few minutes.

Maybe you can reproduce the error. I started with a new project. Those 
are my files:


begin default.template
    Formatted headers and abstracts of selected articles will be shown here
    <webgen:block name=''content''
chain="selected-aricles.template" />
end default.template


begin selected-articles.template
    Those are the selected articles (article-a.html and article-b.html)
    <webgen:block name=''content'' 
chain="single-article.template;article-a.html" />
    <webgen:block name=''content'' 
chain="single-article.template;article-b.html" />
end selected-articles.template


begin single-article.template
    <some-html>  <webgen:block name=''header'' />   
</some-html>
    <some-html>  <webgen:block name=''abstract'' /> 
</some-html>
end single-article.template
   
begin article-a.page
    --- name:content
    here comes the whole content of the article A,
    to be included elsewhere

    --- name:header
    just the header of the article A

    --- name:abstract
    just the abstract of the article A
end article-a.page


begin article-b.page
    (same as article A)
end article-b.page


Any hints appreciated,
thanks a lot,

Michael

Am Sun, 31 Aug 2008 16:24:42 +0200
schrieb Michael Franzl <m.franzl at aon.at>:
> I was experimenting with template chains and detected the following 
> issue with webgen-0.5.3:
> 
>     Generating tree...
>     An error has occurred:   stack level too deep
> 
> The weird thing is that after deleting `webgen.cache`, website 
> compilation is successfully. When `webgen` is run immediately after
> this successful compilation (i.e. without changing any files), the
> error above shows up. After that, *every* compilation will end with
> this error, independent of source files changes.
I have found the problem and I''m working on a solution. Will keep you
informed!

-- Thomas

Am Sun, 31 Aug 2008 16:24:42 +0200
schrieb Michael Franzl <m.franzl at aon.at>:
> I was experimenting with template chains and detected the following 
> issue with webgen-0.5.3:
> 
>     Generating tree...
>     An error has occurred:   stack level too deep
> 
> The weird thing is that after deleting `webgen.cache`, website 
> compilation is successfully. When `webgen` is run immediately after
> this successful compilation (i.e. without changing any files), the
> error above shows up. After that, *every* compilation will end with
> this error, independent of source files changes.
> 
> Deleting `webgen.cache` every time wouldn''t bother me much, but my
> website will have pretty big volume and I estimate computation times
> of up to a few minutes.
> 
> Maybe you can reproduce the error. I started with a new project.
> Those are my files:
Thanks for providing the files. They helped in reproducing the error.
It worked exactly like you said, or more specifically, it didn''t work,
like you said :)

The problem comes from checking if a node or its meta information has
changed. If there are circular dependencies, you will get the `stack
level too deep` error. I have now included a check that prevents from
including one node multiple times in the same change check.

After doing some more updates I will release the next webgen version
with this bug fix at the end of this week.

Thanks again for finding the bug!

-- Thomas