Add SChunk.__len__()

RELEASE_NOTES.md

@@ -7,6 +7,8 @@
 * Support for slices in ``blosc2.get_slice_nchunks()`` when using SChunk
   objects.
 
+* Added a new `Schunk.__len__()` method.
+
 ## Changes from 2.3.2 to 2.4.0
 
 * Updated to latest C-Blosc2 2.12.0.

blosc2/schunk.py

@@ -224,9 +224,12 @@ def __init__(self, chunksize=None, data=None, **kwargs):
         if chunksize is None:
             chunksize = 2**24
             if data is not None:
-                chunksize = data.size * data.itemsize
-                # Make that a multiple of typesize
-                chunksize = chunksize // data.itemsize * data.itemsize
+                if hasattr(data, "itemsize"):
+                    chunksize = data.size * data.itemsize
+                    # Make that a multiple of typesize
+                    chunksize = chunksize // data.itemsize * data.itemsize
+                else:
+                    chunksize = len(data)
             # Use a cap of 256 MB (modern boxes should all have this RAM available)
             if chunksize > 2**28:
                 chunksize = 2**28
@@ -236,6 +239,10 @@ def __init__(self, chunksize=None, data=None, **kwargs):
         self._cparams = super(SChunk, self).get_cparams()
         self._dparams = super(SChunk, self).get_dparams()
 
+    def __len__(self):
+        """Return the number of items in the SChunk."""
+        return self.nbytes // self.typesize
+
     @property
     def cparams(self):
         """