parser error

[RS]

On 27/10/2017 19:06, Bernard Peek wrote:
>>
>>> It is then up to the calling script (get_iplayer.pl) to decide what
>>> action to take in response the action taken by the parser.  It is not
>>> adequate just to allow XML::LibXML to display "parser error" and take
>>> no further action.
>>
>> Even though that's what the XML standard says IS the correct action?
>>
> 
> PMFJI
> 
> I built data transfer standards for the UK's outdoor advertising 
> industry. I deliberately chose to use XML based standards because it 
> enabled automatic validation of data files. The standards were quite 
> specific. All automated systems were required to refuse any files not 
> compatible with the DTD I had on my web server. Data providers were 
> expected to prevalidate any files they sent to any other company.
> 
> This was my main argument for switching to XML from flat-files.
> 
If you are both right about the strictness of the standard, and I have 
to defer to your superior knowledge, why does XML::LibXML have options 
for recovery and validation? According to
http://search.cpan.org/dist/XML-LibXML/lib/XML/LibXML/Parser.pod#PARSER_OPTIONS 
and
http://search.cpan.org/dist/XML-LibXML/lib/XML/LibXML/Error.pod
it also has a choice of Verbose and Quiet error handlers.  Authors can 
use their own error handlers, or remove the error handler altogether. 
An example given is recovery from a missing closing tag.  I have not 
seen a definition of fatal error.  Is a spurious NUL a fatal error?  I 
suspect it is less serious than a missing closing tag.  It is easy to 
recover from; you just ignore it.  Subject to what anyone may tell me, I 
would have thought non-matching tags would be more likely to be a fatal 
error.

It must be remembered that an important function of XML, in contrast to 
other mark up languages, is that it is human readable as well as machine 
readable.

Error recovery must always be appropriate for the importance of 
integrity of the data and the probability of errors.  I can understand 
there are applications where strict compliance is necessary, but 
subtitles does not seem to me to be one of them.

Subtitles for this film used to work with XML::Simple.  A problem only 
occurred with the move to XML::LibXML to support coloured subtitles.  Is 
it possible to configure XML::LibXML to be as error tolerant as XML::Simple?

Best wishes
Richard