urlwrite.m

[Bob Weigel]

If Octave was not compiled with cURL, xmlwrite.oct is created and when
called always returns an error.  This creates a problem when writing
code to work for older versions of Octave in which I would want to
test for xmlwrite using

if exist('xmlwrite')
  [F,success] = xmlwrite(...)
else
  # Use alternantive
end

Because xmlwrite may exist but always returns an error, I would need
to put a try-catch clause

if exist('xmlwrite')
  try
   # Calling xmlwrite
  catch
   # Use alternative
  end
else
  # Use alternantive
end

Would it make sense to set the second output of urlwrite to zero
instead of always returning error?

Also, in configure, if the curl library is not found or if the version found 
does not have curl_easy_escape, we are treated with the same warning as a 
other missing libraries.  Could a warning be added that says "Octave will not 
be able to use URL functions"?

configure: WARNING: UMFPACK not found.  This will result in some lack of 
functionality for sparse matrices.
configure: WARNING: COLAMD not found. This will result in some lack of 
functionality for sparse matrices.
configure: WARNING: CCOLAMD not found. This will result in some lack of 
functionality for sparse matrices.
configure: WARNING: CHOLMOD not found. This will result in some lack of 
functionality for sparse matrices.
configure: WARNING: CXSparse not found. This will result in some lack of 
functionality for sparse matrices.
configure: WARNING: FFTW library not found.  Octave will use the (slower) 
FFTPACK library instead.
configure: WARNING: HDF5 library not found.  Octave will not be able to save 
or load HDF5 data files.

Bob