Re: Using CFFI: dealing with a writeback buffer

Hello Victor,

I think you're looking for something along these lines.

(with-foreign-object (proj :pointer) (osr-export-to-proj-4 handle proj) (let ((p (mem-ref proj :pointer))) (write-line (foreign-string-to-lisp p)) (cpl-free p)))

Cheers, Luís

(painstakingly typed on a phone)

On Tue, Jul 14, 2015, 14:37 Victor bobbie@ua.fm wrote:

Hi all,

I don't know if it is the best place to ask this question, but I'll try it. I am trying to wrap around a following function:

OGRErr OSRExportToProj4(OGRSpatialReferenceH r, char **buff);

This function allocates the string and assigns it to the (char*) pointer passed as buff and then its contents should be copied into a C string and the obtained pointer released via CPLFree();

So, basically, in C a typical usage would be:

char *proj = NULL: OSRExportToProj4(handle, &proj); printf("%s\n", proj); CPLFree(proj);

And the question is: how is this function should be wrapped with CFFI?

Thanks, Victor

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Luís

(sent from my phone)