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Re: RaiseWarn attribute for DBI

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From:
Darren Duncan
Date:
January 17, 2019 19:43
Subject:
Re: RaiseWarn attribute for DBI
Message ID:
26ad75cb-9374-14d0-854d-2801563a538b@darrenduncan.net
Generally speaking, DBI is one of those things where backwards compatibility 
should be the highest concern after security.  There is a time and place to 
break compatibility, and this Print/Raise thing seems way too minor to me for 
that.  I support the version of this that is backwards-compatible and not the 
breaking version. -- Darren Duncan

On 2019-01-17 2:43 AM, pali@cpan.org wrote:
> On Thursday 17 January 2019 11:06:22 Alexander Hartmaier wrote:
>> I'm aware of that, semantic versioning and major versions exist to handle API breakage.
> 
> Such thing is unsupported by CPAN clients. So we cannot use it.
> 
> Anyway, this is question for Tim as DBI maintainer. But I guess he does
> not want to change API of DBI.
> 
>> My question is how to detect if an exception is because of a warn or a die when RaiseWarn is true.
> 
> I guess you can use $dbh->err() method.
> See: https://metacpan.org/pod/DBI#err
> 
> A driver may return 0 from err() to indicate a warning condition after a
> method call. Similarly, a driver may return an empty string to indicate
> a 'success with information' condition. In both these cases the value is
> false but not undef.
> 
> Note that 'success with information' is not warning and therefore DBI's
> PrintWarn or RaiseWarn ignores them.
> 
>> Best regards, Alex
>>
>> On 2019-01-17 10:53, pali@cpan.org wrote:
>>> On Thursday 17 January 2019 10:23:25 Alexander Hartmaier wrote: > I don't see the benefit, Print* should die This would break existing API of DBI. Print just prints and Raise dies. This cannot be changed as there are many applications which depends on this API. > and I'd personally would release a major release and change the defaults as a breaking change: PrintError false, RaiseError true. > Can you name a use case and how to differ between an error and a warning at the error handling side? It is up to the DBI driver or database server what would result in is a warning and what in an error. > Best regards, Alex > > > On 2019-01-17 10:04, pali@cpan.org wrote: > > Hello! What do you think about adding a new attribute $dbh->{RaiseWarn} which cause that warnings reported by DBI drivers would behave like errors? For errors DBI has there $dbh->{PrintError} and $dbh->{RaiseError} attributes. First one is by default true and second one by default false. When PrintWarn is true, the
>>   n all er
>>
>> ror from DBI driver are passed to perl's "warn" function and when RaiseError is true, then errors are passed to perl's "die" function. (Plus there is ability to register own error handler function) Currently DBI has only $dbh->{PrintWarn} attribute to control warnings. When is set to true (by default) all warnings from DBI driver are passed to perl's "warn" function. So I would propose to add $dbh->{RaiseWarn} attribute (off by default) to behave like $dbh->{RaiseError}, but for warnings. I have implemented this attribute and patch is there: https://github.com/perl5-dbi/dbi/pull/71/files
>>
>>
> 


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