Work around a portability bug in ecCodes by re-implementing a function.

Fix #7.

CHANGELOG.rst

@@ -5,7 +5,7 @@ Changelog for cfgrib
 0.9.6 (unreleased)
 ------------------
 
-- Add read-only support on *Windows* after you install *ecCodes* on *conda*.
+- Add support for *Windows* by installing *ecCodes* via *conda*.
   See: `#7 <https://github.com/ecmwf/cfgrib/issues/7>`_
 - Do not set explicit timezone in ``units`` to avoid crashing some versions of xarray.
   See: `#44 <https://github.com/ecmwf/cfgrib/issues/44>`_.

README.rst

@@ -26,10 +26,9 @@ Work in progress:
   see `#40 <https://github.com/ecmwf/cfgrib/issues/40>`_.
 - **Alpha** supports writing the index of a GRIB file to disk, to save a full-file scan on open,
   see `#33 <https://github.com/ecmwf/cfgrib/issues/33>`_.
-- **Alpha** support writing carefully-crafted ``xarray.Dataset``'s to a GRIB1 or GRIB2 file on Linux and MacOS,
-  see the *Advanced write usage* section below,
-  `#18 <https://github.com/ecmwf/cfgrib/issues/18>`_ and
-  `#7 <https://github.com/ecmwf/cfgrib/issues/7>`_,
+- **Alpha** support writing carefully-crafted ``xarray.Dataset``'s to a GRIB1 or GRIB2 file,
+  see the *Advanced write usage* section below and
+  `#18 <https://github.com/ecmwf/cfgrib/issues/18>`_.
 - **Alpha** support translating coordinates to different data models and naming conventions,
   `#24 <https://github.com/ecmwf/cfgrib/issues/24>`_.
 

cfgrib/bindings.py

@@ -599,8 +599,33 @@ def codes_get_api_version():
     return "%d.%d.%d" % (major, minor, patch)
 
 
+def portable_handle_new_from_samples(samplename, product_kind):
+    #
+    # re-implement codes_grib_handle_new_from_samples in a portable way.
+    # imports are here not to pollute the head of the file with (hopfully!) temporary stuff
+    #
+    import os.path
+    import platform
+    handle = ffi.NULL
+    if platform.platform().startswith('Windows'):
+        samplepath = os.path.join(ffi.string(lib.codes_samples_path(ffi.NULL)), samplename + b'.tmpl')
+        try:
+            with open(samplepath) as file:
+                handle = codes_handle_new_from_file(file, product_kind)
+        except FileNotFoundError:
+            pass
+    return handle
+
+
 def codes_new_from_samples(samplename, product_kind=CODES_PRODUCT_GRIB):
     # type: (bytes, int) -> cffi.FFI.CData
+
+    # work around an ecCodes bug on Windows, hopefully this will go away soon
+    handle = portable_handle_new_from_samples(samplename, product_kind)
+    if handle != ffi.NULL:
+        return handle
+    # end of work-around
+
     if product_kind == CODES_PRODUCT_GRIB:
         handle = lib.codes_grib_handle_new_from_samples(ffi.NULL, samplename)
     elif product_kind == CODES_PRODUCT_BUFR:

cfgrib/eccodes.h

@@ -438,6 +438,8 @@ void codes_grib_multi_support_on(codes_context* c);
 */
 void codes_grib_multi_support_off(codes_context* c);
 
+char* codes_samples_path(const codes_context *c);
+
 /**
 *  Get the API version
 *