Add DParams dataclass && avoid rewriting the defaults

doc/reference/storage.rst

@@ -15,3 +15,12 @@ CParams
    :nosignatures:
 
     CParams
+
+DParams
+-------
+
+.. autosummary::
+   :toctree: autofiles/storage
+   :nosignatures:
+
+    DParams

src/blosc2/__init__.py

@@ -213,7 +213,7 @@ class Tuner(Enum):
 
 from .schunk import SChunk, open
 
-from .storage import cpu_info, CParams, cparams_dflts, dparams_dflts, ncores, nthreads, storage_dflts
+from .storage import cpu_info, CParams, cparams_dflts, DParams, dparams_dflts, ncores, nthreads, storage_dflts
 
 
 # Registry for postfilters

src/blosc2/core.py

@@ -1444,10 +1444,15 @@ def decompress2(src: object, dst: object | bytearray = None, **kwargs: dict) ->
     Other Parameters
     ----------------
     kwargs: dict, optional
+        Decompression parameters. The default values are in :ref:`blosc2.DParams`.
         Keyword arguments supported:
 
-            nthreads: int
-                The number of threads to use internally (1 by default).
+            cparams: :class:`blosc2.DParams`
+                All the decompression parameters that you want to use as
+                a :class:`blosc2.DParams` instance.
+            others: Any
+                If `dparams` is not passed, all the parameters of a :class:`blosc2.DParams`
+                can be passed as keyword arguments.
 
     Returns
     -------
@@ -1469,6 +1474,12 @@ def decompress2(src: object, dst: object | bytearray = None, **kwargs: dict) ->
         If the length of :paramref:`src` is smaller than the minimum.
         If :paramref:`dst` is not None and its length is 0.
     """
+    if kwargs is not None:
+        if 'dparams' in kwargs:
+            if len(kwargs) > 1:
+                raise AttributeError("Cannot pass both dparams and other kwargs already included in DParams")
+            kwargs = asdict(kwargs.get('dparams'))
+
     return blosc2_ext.decompress2(src, dst, **kwargs)
 
 

src/blosc2/storage.py

@@ -22,42 +22,6 @@
 # Experiments say that, when using a large number of threads, it is better to not use them all
 nthreads -= nthreads // 8
 
-# Defaults for compression params
-cparams_dflts = {
-    "codec": blosc2.Codec.ZSTD,
-    "codec_meta": 0,
-    "clevel": 1,
-    "use_dict": False,
-    "typesize": 8,
-    "nthreads": nthreads,
-    "blocksize": 0,
-    "splitmode": blosc2.SplitMode.ALWAYS_SPLIT,
-    "filters": [
-        blosc2.Filter.NOFILTER,
-        blosc2.Filter.NOFILTER,
-        blosc2.Filter.NOFILTER,
-        blosc2.Filter.NOFILTER,
-        blosc2.Filter.NOFILTER,
-        blosc2.Filter.SHUFFLE,
-    ],
-    "filters_meta": [0, 0, 0, 0, 0, 0],
-    "tuner": blosc2.Tuner.STUNE,
-}
-"""
-Compression params defaults.
-"""
-
-# Defaults for decompression params
-dparams_dflts = {"nthreads": nthreads}
-"""
-Decompression params defaults.
-"""
-# Default for storage
-storage_dflts = {"contiguous": False, "urlpath": None, "cparams": None, "dparams": None, "io": None}
-"""
-Storage params defaults. This is meant only for :ref:`SChunk <SChunk>` or :ref:`NDArray <NDArray>`.
-"""
-
 
 def default_nthreads():
     return nthreads
@@ -123,4 +87,34 @@ class CParams:
     tuner: blosc2.Tuner = blosc2.Tuner.STUNE
 
     # def __post_init__(self):
-    #     if len(self.filters) > 6:
+    #     if len(self.filters) > 6:
+
+
+@dataclass
+class DParams:
+    """Dataclass for hosting the different decompression parameters.
+
+    Parameters
+    ----------
+    nthreads: int
+        The number of threads to use internally. By default, blosc2 computes
+        a good guess.
+    """
+    nthreads: int = field(default_factory=default_nthreads)
+
+# Defaults for compression params
+cparams_dflts = asdict(CParams())
+"""
+Compression params defaults.
+"""
+
+# Defaults for decompression params
+dparams_dflts = asdict(DParams())
+"""
+Decompression params defaults.
+"""
+# Default for storage
+storage_dflts = {"contiguous": False, "urlpath": None, "cparams": blosc2.CParams(), "dparams": blosc2.DParams}
+"""
+Storage params defaults. This is meant only for :ref:`SChunk <SChunk>` or :ref:`NDArray <NDArray>`.
+"""

tests/test_compress2.py

@@ -28,7 +28,7 @@
                 filters_meta=[10, 0],
                 typesize=4
             )},
-            {"nthreads": 4},
+            {'dparams': blosc2.DParams(nthreads=4)},
         ),
         (
             np.arange(10, dtype="float32"),
@@ -43,7 +43,7 @@
         (
             random.integers(0, 1000, 1000, endpoint=True),
             {'cparams': blosc2.CParams(splitmode=blosc2.SplitMode.ALWAYS_SPLIT, nthreads=5, typesize=4)},
-            {},
+            {'dparams': blosc2.DParams()},
         ),
         (np.arange(45, dtype=np.float64), {'cparams': blosc2.CParams(codec=blosc2.Codec.LZ4HC, typesize=4)}, {}),
         (np.arange(50, dtype=np.int64), {"typesize": 4}, blosc2.dparams_dflts),