Add change log entry for astropy#2292

CHANGES.rst

@@ -67,6 +67,13 @@ oac
 - Fix bug in parsing events that contain html tags (e.g. in their alias
   field). [#2423]
 
+simbad
+^^^^^^
+
+- It is now possible to apply changes through the configuration system at
+  runtime. However, if the corresponding class or instance variables have been
+  specified then they still take precedence. [#2292]
+
 svo_fps
 ^^^^^^^
 

astroquery/simbad/core.py

@@ -271,8 +271,8 @@ class SimbadClass(SimbadBaseQuery):
     (http://simbad.u-strasbg.fr/simbad/sim-help?Page=sim-url)
 
     """
-    SIMBAD_URL = 'http://' + conf.server + '/simbad/sim-script'
-    TIMEOUT = conf.timeout
+    SIMBAD_URL = ''
+    TIMEOUT = None
     WILDCARDS = {
         '*': 'Any string of characters (including an empty one)',
         '?': 'Any character (exactly one character)',
@@ -293,7 +293,7 @@ class SimbadClass(SimbadBaseQuery):
         'query_bibobj_async': 'query bibobj'
     }
 
-    ROW_LIMIT = conf.row_limit
+    ROW_LIMIT = None
 
     # also find a way to fetch the votable fields table from
     # <http://simbad.u-strasbg.fr/simbad/sim-help?Page=sim-fscript#VotableFields>
@@ -305,6 +305,18 @@ def __init__(self):
         super().__init__()
         self._VOTABLE_FIELDS = copy.copy(self._VOTABLE_FIELDS)
 
+    @property
+    def _row_limit(self):
+        return conf.row_limit if self.ROW_LIMIT is None else self.ROW_LIMIT
+
+    @property
+    def _simbad_url(self):
+        return self.SIMBAD_URL or f'https://{conf.server}/simbad/sim-script'
+
+    @property
+    def _timeout(self):
+        return conf.timeout if self.TIMEOUT is None else self.TIMEOUT
+
     def list_wildcards(self):
         """
         Displays the available wildcards that may be used in Simbad queries and
@@ -513,8 +525,8 @@ def query_criteria_async(self, *args, **kwargs):
 
         request_payload = self._args_to_payload(caller='query_criteria_async',
                                                 *args, **kwargs)
-        response = self._request("POST", self.SIMBAD_URL, data=request_payload,
-                                 timeout=self.TIMEOUT, cache=cache)
+        response = self._request("POST", self._simbad_url, data=request_payload,
+                                 timeout=self._timeout, cache=cache)
         return response
 
     def query_object(self, object_name, wildcard=False, verbose=False,
@@ -577,8 +589,8 @@ def query_object_async(self, object_name, wildcard=False, cache=True,
         if get_query_payload:
             return request_payload
 
-        response = self._request("POST", self.SIMBAD_URL, data=request_payload,
-                                 timeout=self.TIMEOUT, cache=cache)
+        response = self._request("POST", self._simbad_url, data=request_payload,
+                                 timeout=self._timeout, cache=cache)
         return response
 
     def query_objects(self, object_names, wildcard=False, verbose=False,
@@ -715,8 +727,8 @@ def query_region_async(self, coordinates, radius=2*u.arcmin,
         if get_query_payload:
             return request_payload
 
-        response = self._request("POST", self.SIMBAD_URL, data=request_payload,
-                                 timeout=self.TIMEOUT, cache=cache)
+        response = self._request("POST", self._simbad_url, data=request_payload,
+                                 timeout=self._timeout, cache=cache)
         return response
 
     def query_catalog(self, catalog, verbose=False, cache=True,
@@ -772,8 +784,8 @@ def query_catalog_async(self, catalog, cache=True, get_query_payload=False):
         if get_query_payload:
             return request_payload
 
-        response = self._request("POST", self.SIMBAD_URL, data=request_payload,
-                                 timeout=self.TIMEOUT, cache=cache)
+        response = self._request("POST", self._simbad_url, data=request_payload,
+                                 timeout=self._timeout, cache=cache)
         return response
 
     def query_bibobj(self, bibcode, verbose=False, get_query_payload=False):
@@ -826,8 +838,8 @@ def query_bibobj_async(self, bibcode, cache=True, get_query_payload=False):
         if get_query_payload:
             return request_payload
 
-        response = self._request("POST", self.SIMBAD_URL, data=request_payload,
-                                 timeout=self.TIMEOUT, cache=cache)
+        response = self._request("POST", self._simbad_url, data=request_payload,
+                                 timeout=self._timeout, cache=cache)
         return response
 
     def query_bibcode(self, bibcode, wildcard=False, verbose=False,
@@ -894,8 +906,8 @@ def query_bibcode_async(self, bibcode, wildcard=False, cache=True,
         if get_query_payload:
             return request_payload
 
-        response = self._request("POST", self.SIMBAD_URL, cache=cache,
-                                 data=request_payload, timeout=self.TIMEOUT)
+        response = self._request("POST", self._simbad_url, data=request_payload,
+                                 timeout=self._timeout, cache=cache)
 
         return response
 
@@ -950,8 +962,8 @@ def query_objectids_async(self, object_name, cache=True,
         if get_query_payload:
             return request_payload
 
-        response = self._request("POST", self.SIMBAD_URL, data=request_payload,
-                                 timeout=self.TIMEOUT, cache=cache)
+        response = self._request("POST", self._simbad_url, data=request_payload,
+                                 timeout=self._timeout, cache=cache)
 
         return response
 
@@ -988,8 +1000,8 @@ def _args_to_payload(self, *args, **kwargs):
         votable_header = self._get_query_header(get_raw)
         votable_footer = self._get_query_footer(get_raw)
 
-        if self.ROW_LIMIT > 0:
-            script = "set limit " + str(self.ROW_LIMIT)
+        if self._row_limit > 0:
+            script = "set limit " + str(self._row_limit)
         script = "\n".join([script, votable_header, command])
         using_wildcard = False
         if kwargs.get('wildcard'):

astroquery/simbad/tests/test_simbad.py

@@ -383,6 +383,28 @@ def test_query_criteria2(patch_post):
     assert 'otype=SNR' in S._last_query.data['script']
 
 
+def test_config_runtime_change():
+    sb = simbad.Simbad()
+
+    assert sb._row_limit == 0
+    with simbad.conf.set_temp('row_limit', 7):
+        assert sb._row_limit == 7
+        sb.ROW_LIMIT = 3
+        assert sb._row_limit == 3
+
+    assert sb._simbad_url == 'https://simbad.u-strasbg.fr/simbad/sim-script'
+    with simbad.conf.set_temp('server', 'simbad.harvard.edu'):
+        assert sb._simbad_url == 'https://simbad.harvard.edu/simbad/sim-script'
+        sb.SIMBAD_URL = 'asdfg'
+        assert sb._simbad_url == 'asdfg'
+
+    assert sb._timeout == 60
+    with simbad.conf.set_temp('timeout', 5):
+        assert sb._timeout == 5
+        sb.TIMEOUT = 3
+        assert sb._timeout == 3
+
+
 def test_simbad_settings1():
     sb = simbad.core.Simbad()
     assert sb.get_votable_fields() == ['main_id', 'coordinates']

astroquery/simbad/tests/test_simbad_remote.py

@@ -7,7 +7,7 @@
 import astropy.units as u
 from astropy.table import Table
 from astroquery.utils.mocks import MockResponse
-from astroquery.simbad import Simbad
+from astroquery.simbad import conf, Simbad
 # Maybe we need to expose SimbadVOTableResult to be in the public API?
 from astroquery.simbad.core import SimbadVOTableResult
 
@@ -30,6 +30,23 @@ def fin():
         request.addfinalizer(fin)
         return my_temp_dir
 
+    def test_config_runtime_change(self, temp_dir):
+        simbad = Simbad()
+        simbad.cache_location = temp_dir
+        with conf.set_temp('server', 'simbad.harvard.edu'):
+            response = simbad.query_bibobj_async('2006AJ....131.1163S')
+            assert response.url == 'https://simbad.harvard.edu/simbad/sim-script'
+        response = simbad.query_bibobj_async('2006AJ....131.1163S')
+        assert response.url == 'https://simbad.u-strasbg.fr/simbad/sim-script'
+
+        simbad = Simbad()
+        with conf.set_temp('row_limit', 4):
+            result = simbad.query_bibobj('2005A&A.430.165F')
+            assert len(result) == 4
+            simbad.ROW_LIMIT = 5
+            result = simbad.query_bibobj('2005A&A.430.165F')
+            assert len(result) == 5
+
     def test_query_criteria1(self, temp_dir):
         simbad = Simbad()
         simbad.cache_location = temp_dir

docs/simbad/simbad.rst

@@ -245,10 +245,9 @@ instance to query the ESO catalog:
 
 .. code-block:: python
 
-    >>> from astroquery.simbad import Simbad
-    >>> limitedSimbad = Simbad()
-    >>> limitedSimbad.ROW_LIMIT = 6
-    >>> result_table = limitedSimbad.query_catalog('eso')
+    >>> from astroquery.simbad import conf, Simbad
+    >>> with conf.set_temp("row_limit", 6):
+    >>>     result_table = Simbad.query_catalog("eso")
     >>> print(result_table)
 
     MAIN_ID              RA      ... COO_WAVELENGTH     COO_BIBCODE
@@ -532,39 +531,57 @@ Customizing the default settings
 ================================
 
 There may be times when you wish to change the defaults that have been set for
-the Simbad queries.
+the Simbad queries. Items defined through the `astropy configuration system
+<https://docs.astropy.org/en/stable/config/index.html>`_ can be modified
+persistently by editing the ``astroquery`` configuration file, or for the
+duration of the active Python session at runtime. For every such configuration
+item there also exists a corresponding class attribute, which provides an
+alternative way of changing the defaults, but if one of those attributes is
+modified then the corresponding configuration item becomes inactive.
 
 Changing the row limit
 ----------------------
 
-
-To fetch all the rows in the result, the row limit must be set to 0. However for some
-queries, results are likely to be very large, in such cases it may be best to
-limit the rows to a smaller number. If you want to do this only for the current
-python session then:
-
-.. code-block:: python
-
+By default the number of rows in the query results is not limited (done by
+specifying the limit to be 0). However, for some queries the results can be
+very large. In such cases it may be useful to set a limit to the number of
+rows. This can be done through the :attr:`~astroquery.simbad.Conf.row_limit`
+configuration item, or the corresponding
+:attr:`~astroquery.simbad.SimbadClass.ROW_LIMIT` class attribute::
+
+    >>> from astroquery.simbad import conf
+    >>> with conf.set_temp("row_limit", 10):
+    ...     # Row limit is set to 10 within this code block.
+    ...     pass
     >>> from astroquery.simbad import Simbad
-    >>> Simbad.ROW_LIMIT = 15 # now any query fetches at most 15 rows
-
-If you would like to make your choice persistent, then you can do this by
-modifying the setting in the Astroquery configuration file.
+    >>> # Setting the row limit to 15 for the instance.
+    >>> Simbad.ROW_LIMIT = 15
 
 Changing the timeout
 --------------------
 
+The timeout is the time limit in seconds for establishing the connection with
+the Simbad server and by default it is set to 60 seconds. It can be modified
+through the :attr:`~astroquery.simbad.Conf.timeout` configuration item, or the
+corresponding :attr:`~astroquery.simbad.SimbadClass.TIMEOUT` class attribute.
 
-The timeout is the time limit in seconds for establishing connection with the
-Simbad server and by default it is set to 100 seconds. You may want to modify
-this - again you can do this at run-time if you want to adjust it only for the
-current session. To make it persistent, you must modify the setting in the
-Astroquery configuration file.
+Changing the server
+-------------------
 
-.. code-block:: python
+By default all queries are sent to ``simbad.u-strasbg.fr``, but it is also
+possible to connect to the mirror at ``simbad.harvard.edu`` instead. This can
+be specified through the :attr:`~astroquery.simbad.Conf.server` configuration
+item::
+
+    >>> from astroquery.simbad import conf
+    >>> conf.server = "simbad.u-strasbg.fr"
+
+The corresponding class attribute is
+:attr:`~astroquery.simbad.SimbadClass.SIMBAD_URL`, and differently from the
+configuration item it requires the entire URL to be specified::
 
     >>> from astroquery.simbad import Simbad
-    >>> Simbad.TIMEOUT = 60 # sets the timeout to 60s
+    >>> Simbad.SIMBAD_URL = "http://simbad.u-strasbg.fr/simbad/sim-script"
 
 Specifying which VOTable fields to include in the result
 --------------------------------------------------------