REF: pytables remove IndexCol.infer, move attr setting to constructors

pandas/io/pytables.py

@@ -1895,6 +1895,9 @@ def __init__(
         freq=None,
         tz=None,
         index_name=None,
+        table=None,
+        meta=None,
+        metadata=None,
     ):
 
         if not isinstance(name, str):
@@ -1910,9 +1913,9 @@ def __init__(
         self.freq = freq
         self.tz = tz
         self.index_name = index_name
-        self.table = None
-        self.meta = None
-        self.metadata = None
+        self.table = table
+        self.meta = meta
+        self.metadata = metadata
 
         if pos is not None:
             self.set_pos(pos)
@@ -1968,19 +1971,6 @@ def is_indexed(self) -> bool:
         #  'error: "None" has no attribute "cols"'
         return getattr(self.table.cols, self.cname).is_indexed  # type: ignore
 
-    def copy(self):
-        new_self = copy.copy(self)
-        return new_self
-
-    def infer(self, handler: "Table"):
-        """infer this column from the table: create and return a new object"""
-        table = handler.table
-        new_self = self.copy()
-        new_self.table = table
-        new_self.get_attr()
-        new_self.read_metadata(handler)
-        return new_self
-
     def convert(self, values: np.ndarray, nan_rep, encoding: str, errors: str):
         """ set the values from this selection: take = take ownership """
         assert isinstance(values, np.ndarray), type(values)
@@ -2136,10 +2126,6 @@ def set_attr(self):
         """ set the kind for this column """
         setattr(self.attrs, self.kind_attr, self.kind)
 
-    def read_metadata(self, handler):
-        """ retrieve the metadata for this columns """
-        self.metadata = handler.read_metadata(self.cname)
-
     def validate_metadata(self, handler: "AppendableTable"):
         """ validate that kind=category does not change the categories """
         if self.meta == "category":
@@ -2207,10 +2193,27 @@ class DataCol(IndexCol):
     _info_fields = ["tz", "ordered"]
 
     def __init__(
-        self, name: str, values=None, kind=None, typ=None, cname=None, pos=None,
+        self,
+        name: str,
+        values=None,
+        kind=None,
+        typ=None,
+        cname=None,
+        pos=None,
+        table=None,
+        meta=None,
+        metadata=None,
     ):
         super().__init__(
-            name=name, values=values, kind=kind, typ=typ, pos=pos, cname=cname
+            name=name,
+            values=values,
+            kind=kind,
+            typ=typ,
+            pos=pos,
+            cname=cname,
+            table=table,
+            meta=meta,
+            metadata=metadata,
         )
         self.dtype = None
         self.data = None
@@ -3420,10 +3423,8 @@ def get_attrs(self):
         self.encoding = _ensure_encoding(getattr(self.attrs, "encoding", None))
         self.errors = _ensure_decoded(getattr(self.attrs, "errors", "strict"))
         self.levels = getattr(self.attrs, "levels", None) or []
-        self.index_axes = [a.infer(self) for a in self.indexables if a.is_an_indexable]
-        self.values_axes = [
-            a.infer(self) for a in self.indexables if not a.is_an_indexable
-        ]
+        self.index_axes = [a for a in self.indexables if a.is_an_indexable]
+        self.values_axes = [a for a in self.indexables if not a.is_an_indexable]
         self.metadata = getattr(self.attrs, "metadata", None) or []
 
     def validate_version(self, where=None):
@@ -3466,7 +3467,18 @@ def indexables(self):
         # index columns
         for i, (axis, name) in enumerate(self.attrs.index_cols):
             atom = getattr(desc, name)
-            index_col = IndexCol(name=name, axis=axis, pos=i, typ=atom)
+            md = self.read_metadata(name)
+            meta = "category" if md is not None else None
+            index_col = IndexCol(
+                name=name,
+                axis=axis,
+                pos=i,
+                typ=atom,
+                table=self.table,
+                meta=meta,
+                metadata=md,
+            )
+            index_col.get_attr()
             _indexables.append(index_col)
 
         # values columns
@@ -3481,7 +3493,19 @@ def f(i, c):
 
             atom = getattr(desc, c)
             adj_name = _maybe_adjust_name(c, self.version)
-            return klass(name=adj_name, cname=c, pos=base_pos + i, typ=atom)
+            md = self.read_metadata(c)
+            meta = "category" if md is not None else None
+            obj = klass(
+                name=adj_name,
+                cname=c,
+                pos=base_pos + i,
+                typ=atom,
+                table=self.table,
+                meta=meta,
+                metadata=md,
+            )
+            obj.get_attr()
+            return obj
 
         # Note: the definition of `values_cols` ensures that each
         #  `c` below is a str.
@@ -4474,10 +4498,8 @@ def get_attrs(self):
         self.nan_rep = None
         self.levels = []
 
-        self.index_axes = [a.infer(self) for a in self.indexables if a.is_an_indexable]
-        self.values_axes = [
-            a.infer(self) for a in self.indexables if not a.is_an_indexable
-        ]
+        self.index_axes = [a for a in self.indexables if a.is_an_indexable]
+        self.values_axes = [a for a in self.indexables if not a.is_an_indexable]
         self.data_columns = [a.name for a in self.values_axes]
 
     @cache_readonly
@@ -4488,13 +4510,31 @@ def indexables(self):
         # TODO: can we get a typ for this?  AFAICT it is the only place
         #  where we aren't passing one
         # the index columns is just a simple index
-        _indexables = [GenericIndexCol(name="index", axis=0)]
+        md = self.read_metadata("index")
+        meta = "category" if md is not None else None
+        index_col = GenericIndexCol(
+            name="index", axis=0, table=self.table, meta=meta, metadata=md
+        )
+        index_col.get_attr()
+
+        _indexables = [index_col]
 
         for i, n in enumerate(d._v_names):
             assert isinstance(n, str)
 
             atom = getattr(d, n)
-            dc = GenericDataIndexableCol(name=n, pos=i, values=[n], typ=atom)
+            md = self.read_metadata(n)
+            meta = "category" if md is not None else None
+            dc = GenericDataIndexableCol(
+                name=n,
+                pos=i,
+                values=[n],
+                typ=atom,
+                table=self.table,
+                meta=meta,
+                metadata=md,
+            )
+            dc.get_attr()
             _indexables.append(dc)
 
         return _indexables