[Gdal-dev] Layer Equality

[Frank Warmerdam]

Simon Perkins wrote:
> Hi,
> 
> I'm trying to do something that on the face of it should be fairly 
> straightforward, but I can't quite see how to do it in the best way. 
> Basically, I have an open OGRLayer, and I'd like to see if this OGRLayer 
> is the same as another layer in the same OGRDataSource, which I only 
> know by name. Ultimately, if the named layer already exists, I'd like to 
> delete it and replace it with the contents of the OGRLayer. Unless, that 
> named layer is actually the same layer as the existing OGRLayer, in 
> whcih case nothing needs to happen. The question is, how can I check for 
> this? I know the index number of the existing OGRLayer, but I'm not sure 
> I see how to determine the index number of the named layer to see if 
> they are the same. Similarly, I'm not sure how to get the name of the 
> existing OGRLayer to use that as a comparison. Any ideas?

Simon,

Somewhat obtusely, the only way to get the name of a layer is to look in
the OGRFeatureDefn associated with it.  So in ogrinfo this is done as:

                 printf( "%d: %s",
                         iLayer+1,
                         poLayer->GetLayerDefn()->GetName() );

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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