I'm afraid I've missed this change quite much since it was so nicely
backwards compatible.
It doesn't make sense to have two classes in the Perl bindings when
there is really only one in the library - it's too confusing. That means
I'll need to remove the OGR Driver and DataSource classes completely and
leave only GDAL Driver and Dataset classes.
That's a backwards incompatible change and it should have been made in
the 2.0 but it'll happen in 2.1 of the Perl bindings.
Ari
On 13.11.2015 16:37, Even Rouault wrote:
Le vendredi 13 novembre 2015 15:17:40, Ari Jolma a écrit :
On 13.11.2015 15:58, Even Rouault wrote:
Le vendredi 13 novembre 2015 14:48:02, Ari Jolma a écrit :
OGR_Dr_Open became deprecated in 2.0 but it is still the main method to
open vector datasets in the bindings.
I just realized that I would need one method to open all data sets.
OpenEx seems to be it but I would still need to cast the object into a
Dataset or a DataSource.
Just don't cast. You can use a Dataset for all purposes since the
OGR_DS_XXXX API has been transposed to GDALDatasetXXXX and is already
available in GDALDatasetShadow
Swig imposes typechecks that prevent that. It is like with the GDALGrid,
which takes a vector dataset.
Not sure if it is a "swig" limitation, or something in the Perl bindings. But
the Python and Java bindings for sure can use the vector part of
GDALDatasetShadow.
I had to write an explicit cast function
for DataSource object into a Dataset object. Which I now realize is
probably not safe since there is an explicit warning against that in the
docs.
At the C level, you can technically cast a GDALDatasetH to a OGRDatasourceH
since the OGR_DS_ C functions end up calling methods of GDALDataset class. But
you cannot cast a GDALDataset* to a OGRDatasource* since OGRDatasource* has a
few virtual methods not available in GDALDataset*
Maybe OpenEx should be the preferred way to
open any data set also with the bindings.
However, I don't seem to find good way to tell whether the data set
object OpenEx gives me is a raster or a vector. Is there such?
If you open with OpenEx(filename, OF_VECTOR), so read-only + vector, then
the few drivers that support vector and raster will return NULL if the
dataset has no vector data and just raster. If you open with
OpenEx(filename, OF_VECTOR | OF_UPDATE) and they support update mode,
then they will return non-NULL even if the dataset has no vector data. A
robust way of checking if there's vector data is to check
GetLayerCount() != 0.
Thanks.
I have so far ignored the OpenEx method. I'll develop it so in the Perl
bindings that it will return a raster dataset object or a vector data
set object depending whether the returned handle is raster or vector.
I'll also deprecate the old Open methods in the Perl bindings.
Ari
Even
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