dont consider Py to be a table

Author: Christopher Doris

docs/src/releasenotes.md

@@ -8,6 +8,8 @@
   column types; better handling of non-string column names; columns are usually wrappers
   (`PyArray` or `PyList`). Constructor arguments have changed. Dict methods have been
   removed (basically only the Tables interface is supported).
+* **Breaking.** A `Py` which is convertible to `PyTable` is no longer considered to be a
+  table itself; you must convert explicitly.
 * Adds `pyhasitem` and 3-arg `pygetitem`.
 * Extends `Base.get`, `Base.get!`, `Base.haskey` and 2-arg `Base.hash` for `Py`.
 * `PyArray` can now have any element type when the underlying array is of Python objects.

src/pywrap/PyTable.jl

@@ -1,18 +1,18 @@
 """
-    PyTable
+    PyTable(x)
 
-Abstract type for Python wrappers which may be interpretable as Tables.jl-compatible tables.
+Wrap `x` as a Tables.jl-compatible table.
 
-If `pyconvert(PyTable, x::Py)` is a table, then `x` is also a table.
+`PyTable` is an abstract type. See [`PyPandasDataFrame`](@ref) for a concrete example.
 """
 abstract type PyTable end
 export PyTable
 
 PyTable(x) = pyconvert(PyTable, x)
 
-Tables.istable(x::Py) = Tables.istable(@pyconvert(PyTable, x, return false))
-Tables.rowaccess(x::Py) = Tables.rowaccess(@pyconvert(PyTable, x, return false))
-Tables.rows(x::Py) = Tables.rows(pyconvert(PyTable, x))
-Tables.columnaccess(x::Py) = Tables.columnaccess(@pyconvert(PyTable, x, return false))
-Tables.columns(x::Py) = Tables.columns(pyconvert(PyTable, x))
-Tables.materializer(x::Py) = Tables.materializer(pyconvert(PyTable, x))
+# Tables.istable(x::Py) = Tables.istable(@pyconvert(PyTable, x, return false))
+# Tables.rowaccess(x::Py) = Tables.rowaccess(@pyconvert(PyTable, x, return false))
+# Tables.rows(x::Py) = Tables.rows(pyconvert(PyTable, x))
+# Tables.columnaccess(x::Py) = Tables.columnaccess(@pyconvert(PyTable, x, return false))
+# Tables.columns(x::Py) = Tables.columns(pyconvert(PyTable, x))
+# Tables.materializer(x::Py) = Tables.materializer(pyconvert(PyTable, x))