Re: Updating to DBI 1.55 breaks DBD::DB2 due to change in DBIc_CACHED_KIDS

Tim Bunce wrote:
> Umm, okay. The key problem here is that DBD::DB2 isn't using the
> Driver.xst 'driver template' file that the DBI provides.
> 
> This means that, apart from duplicating a bunch of code, you're also
> missing out on a bunch of optimizations.
> 
> The Driver.xst file and related info is discussed in
> http://search.cpan.org/~timb/DBI/lib/DBI/DBD.pm
> 
> Take a look at others drivers, like DBD::Sybase and/or DBD::Oracle, for more examples.
> 
> If you're desparate for a quick fix you can use this code instead:
> 
>         SV **svp = hv_fetch((HV*)SvRV(h), "CachedKids", 10, 0);
>         if (svp && SvROK(*svp) && SvTYPE(SvRV(*svp)) == SVt_PVHV) {
>             hv_clear((HV*)SvRV(*svp));
>         }
> 
> but you're likely to bump into similar issues in later versions.
> 
> Driver.xst is the way to go.
> 
> Tim.

Tim,

Would you mind expanding on this a little for me. Someone on MAC OS X is 
getting "invalid lvalue in assignment" on the lines in ODBC.xsi containing

DBIc_CACHED_KIDS(imp_dbh) = Nullhv

which I notice may resolve to Nullhv = Nullhv.

Is DBD::ODBC doing the wrong thing?

Martin
-- 
Martin J. Evans
Easysoft Limited
http://www.easysoft.com

> On Tue, May 15, 2007 at 10:56:13AM -0500, Swetha Patel wrote:
>>    Hi Mr. Bunce,
>>
>>    I work for IBM, and was trying to update the DBD::DB2, so that it works with DBI 1.55. In doing so I
>>    came accross a compile error
>>    "DB2.xs", line 115.9: 1506-025 (S) Operand must be a modifiable lvalue.
>>    Line 115 is: DBIc_CACHED_KIDS(imp_dbh) = Nullhv.
>>
>>    In our code it has effectd these three lines (in DB2.xs):
>>
>>    if (DBIc_CACHED_KIDS(imp_dbh)) {
>>    SvREFCNT_dec(DBIc_CACHED_KIDS(imp_dbh));
>>    DBIc_CACHED_KIDS(imp_dbh) = Nullhv;
>>    }
>>
>>    I noticed that DBIc_CACHED_KIDS in DBI 1.53 was a macro for _imp2com(imp, cached_kids).
>>    And _imp2com(p,f) is a macro for ((p)->com.f).
>>
>>    So in effect DBIc_CACHED_KIDS(imp_dbh) became imp->com.cached_kids in DBI 1.53.
>>
>>    But in DBI 1.55
>>    #define DBIc_CACHED_KIDS(imp) Nullhv
>>    And in effect in DBI 1.55 it becomes
>>    Nullhv = Nullhv;
>>    And hence the compile error.
>>    I am not sure what imp->com.cached_kids is used for.
>>    I have also done a diff on the two versions of DBI.xs, and noticed that these three lines where deleted
>>    in the new DBI.xs, although there were some other things added.
>>    Any information on this change and information regarding the replacement for this change is greatly
>>    appreciated.
>>
>>    Thanks,
>>    Swetha Patel
>>    [email protected]
> 
> 
>