#429 Alien::Proj4->load_projection_information parses PJ_sch parameters incorrectly

[Bas Couwenberg]

While updating the Debian package to 2.017 the lintian QA tool reported pod2man errors for PDL::Transform::Proj4 because it detected:

POD ERRORS
       Hey! The above document had some coding errors, which are explained below:

       Around line 2412:
           Expected '=item *'

       Around line 2414:
           Expected '=item *'

       Around line 2416:
           Expected '=item *'

       Around line 2418:
           Expected '=item *'

This is caused by the sch projection using a slightly different description format which results in the following Proj4.pm:

=head2 t_proj_sch

Autogenerated transformation function for Proj4 projection code sch.

The full name for this projection is Spherical Cross-track Height.

Projection Parameters

=for options

=over 4

=item

=item

=item

=item

=item

=item

=item h_0

=item phdg_0

=item plat_0

=item plon_0

=back



=cut


sub t_proj_sch
    { PDL::Transform::Proj4::sch->new( @_ ); }

The sch projection using spaces around the equal signs unlike most other projections:

PROJ_HEAD(sch, "Spherical Cross-track Height") "\n\tMisc\n\tplat_0 = ,plon_0 = , phdg_0 = ,[h_0 = ]";

See: https://github.com/OSGeo/proj.4/blob/4.9.3/src/PJ_sch.c#L51

Most other projection use a description format like:

PROJ_HEAD(aea, "Albers Equal Area") "\n\tConic Sph&Ell\n\tlat_1= lat_2=";

See: https://github.com/OSGeo/proj.4/blob/4.9.3/src/PJ_aea.c#L36

I've patched the POD generator to skip empty parameters to work around this issue (attached as manpage-has-errors-from-pod2man.patch):

--- a/Lib/Transform/Proj4/Proj4.pd
+++ b/Lib/Transform/Proj4/Proj4.pd
@@ -469,7 +469,7 @@ ENDTEMPLATE
     {
         $doc_param_list .= "\nProjection Parameters\n\n=for options\n\n=over 4\n\n";
         foreach my $param ( sort @{ $projection->{PARAMS}->{PROJ} } )

-            { $doc_param_list .= "=item $param\n\n"; }
+            { next if(!$param); $doc_param_list .= "=item $param\n\n"; }
            $doc_param_list .= "=back\n\n";
     }

The sch projection should also be fixed to use a more consistent description format for which I'll send a patch to Proj4 upstream. This should avoid the need to fix the parsing in Alien::Proj4.

Please consider applying manpage-has-errors-from-pod2man.patch to handle the issue with Proj4 >= 4.9.3-RC1.

[Bas Couwenberg]

For the changes in Proj4 to make the description consistent, see:

https://github.com/OSGeo/proj.4/pull/427

The PR has been merged which should get the fix included in Proj4 4.9.4 expected to be released in about a year (4.9.3 was released last month).

[Chris Marshall]

Patch applied and should appear in the next PDL distribution release. Thanks.