DEPR: Remove literal string input for read_html

doc/source/user_guide/io.rst

@@ -2664,7 +2664,7 @@ Links can be extracted from cells along with the text using ``extract_links="all
     """
 
     df = pd.read_html(
-        html_table,
+        StringIO(html_table),
         extract_links="all"
     )[0]
     df

doc/source/whatsnew/v0.24.0.rst

@@ -286,7 +286,7 @@ value. (:issue:`17054`)
 
 .. ipython:: python
 
-    result = pd.read_html("""
+    result = pd.read_html(StringIO("""
       <table>
         <thead>
           <tr>
@@ -298,7 +298,7 @@ value. (:issue:`17054`)
             <td colspan="2">1</td><td>2</td>
           </tr>
         </tbody>
-      </table>""")
+      </table>"""))
 
 *Previous behavior*:
 

doc/source/whatsnew/v2.1.0.rst

@@ -298,13 +298,15 @@ Deprecations
 - Deprecated constructing :class:`SparseArray` from scalar data, pass a sequence instead (:issue:`53039`)
 - Deprecated falling back to filling when ``value`` is not specified in :meth:`DataFrame.replace` and :meth:`Series.replace` with non-dict-like ``to_replace`` (:issue:`33302`)
 - Deprecated literal json input to :func:`read_json`. Wrap literal json string input in ``io.StringIO`` instead. (:issue:`53409`)
+- Deprecated literal string/bytes input to :func:`read_html`. Wrap literal string/bytes input in ``io.StringIO`` / ``io.BytesIO`` instead. (:issue:`53767`)
 - Deprecated option "mode.use_inf_as_na", convert inf entries to ``NaN`` before instead (:issue:`51684`)
 - Deprecated parameter ``obj`` in :meth:`GroupBy.get_group` (:issue:`53545`)
 - Deprecated positional indexing on :class:`Series` with :meth:`Series.__getitem__` and :meth:`Series.__setitem__`, in a future version ``ser[item]`` will *always* interpret ``item`` as a label, not a position (:issue:`50617`)
 - Deprecated strings ``T``, ``t``, ``L`` and ``l`` denoting units in :func:`to_timedelta` (:issue:`52536`)
 - Deprecated the "method" and "limit" keywords on :meth:`Series.fillna`, :meth:`DataFrame.fillna`, :meth:`SeriesGroupBy.fillna`, :meth:`DataFrameGroupBy.fillna`, and :meth:`Resampler.fillna`, use ``obj.bfill()`` or ``obj.ffill()`` instead (:issue:`53394`)
 - Deprecated the ``method`` and ``limit`` keywords in :meth:`DataFrame.replace` and :meth:`Series.replace` (:issue:`33302`)
 - Deprecated values "pad", "ffill", "bfill", "backfill" for :meth:`Series.interpolate` and :meth:`DataFrame.interpolate`, use ``obj.ffill()`` or ``obj.bfill()`` instead (:issue:`53581`)
+-
 
 .. ---------------------------------------------------------------------------
 .. _whatsnew_210.performance:

pandas/io/html.py

@@ -17,13 +17,15 @@
     Sequence,
     cast,
 )
+import warnings
 
 from pandas._libs import lib
 from pandas.compat._optional import import_optional_dependency
 from pandas.errors import (
     AbstractMethodError,
     EmptyDataError,
 )
+from pandas.util._exceptions import find_stack_level
 from pandas.util._validators import check_dtype_backend
 
 from pandas.core.dtypes.common import is_list_like
@@ -36,6 +38,8 @@
 from pandas.io.common import (
     file_exists,
     get_handle,
+    is_file_like,
+    is_fsspec_url,
     is_url,
     stringify_path,
     urlopen,
@@ -1023,6 +1027,10 @@ def read_html(
         lxml only accepts the http, ftp and file url protocols. If you have a
         URL that starts with ``'https'`` you might try removing the ``'s'``.
 
+        .. deprecated:: 2.1.0
+            Passing html literal strings is deprecated.
+            Wrap literal string/bytes input in ``io.StringIO``/``io.BytesIO`` instead.
+
     match : str or compiled regular expression, optional
         The set of tables containing text matching this regex or string will be
         returned. Unless the HTML is extremely simple you will probably need to
@@ -1178,6 +1186,22 @@ def read_html(
 
     io = stringify_path(io)
 
+    if isinstance(io, str) and not any(
+        [
+            is_file_like(io),
+            file_exists(io),
+            is_url(io),
+            is_fsspec_url(io),
+        ]
+    ):
+        warnings.warn(
+            "Passing literal html to 'read_html' is deprecated and "
+            "will be removed in a future version. To read from a "
+            "literal string, wrap it in a 'StringIO' object.",
+            FutureWarning,
+            stacklevel=find_stack_level(),
+        )
+
     return _parse(
         flavor=flavor,
         io=io,