Trac #30607: Replace use of sage.misc.package.PackageNotFoundError, is_package_installed by features

Release Manager · Release Manager · commit ef0ab126cae1 · 2020-10-04T23:57:03.000+02:00
In this ticket and #30616, we get rid of the remaining uses of `PackageNotFoundError` for dealing with optional extensions etc. by using `sage.features` instead. {{{ $ git grep sage.misc.package src/sage/databases/cremona.py: from sage.misc.package import is_package_installed src/sage/databases/jones.py: from sage.misc.package import PackageNotFoundError src/sage/game_theory/normal_form_game.py: from sage.misc.package import PackageNotFoundError src/sage/game_theory/normal_form_game.py: from sage.misc.package import PackageNotFoundError src/sage/graphs/graph.py: from sage.misc.package import PackageNotFoundError src/sage/graphs/graph.py: from sage.misc.package import PackageNotFoundError src/sage/graphs/graph.py: from sage.misc.package import PackageNotFoundError src/sage/groups/braid.py: from sage.misc.package import PackageNotFoundError src/sage/matrix/matrix_space.py: from sage.misc.package import PackageNotFoundError src/sage/sat/solvers/cryptominisat.py: from sage.misc.package import PackageNotFoundError src/sage/sat/solvers/picosat.py: from sage.misc.package import PackageNotFoundError }}} After this ticket and #30616, only uses for optional packages that do not exist any more remain. {{{ src/sage/interfaces/kash.py: from sage.misc.package import PackageNotFoundError src/sage/rings/polynomial/multi_polynomial_ideal.py: from sage.misc.package import PackageNotFoundError }}} (see #30617 for `ginv`, #25488 for `kash`) URL: https://trac.sagemath.org/30607 Reported by: mkoeppe Ticket author(s): Matthias Koeppe Reviewer(s): Sébastien Labbé
diff --git a/src/sage/databases/jones.py b/src/sage/databases/jones.py
@@ -74,9 +74,9 @@
 
 from sage.misc.persist import load, save
 
-from sage.misc.package import PackageNotFoundError
+from sage.features.databases import DatabaseJones
 
-JONESDATA = os.path.join(SAGE_SHARE, 'jones')
+JONESDATA = os.path.join(SAGE_SHARE, 'jones')  # should match the filename set in DatabaseJones
 
 
 def sortkey(K):
@@ -226,10 +226,7 @@ def get(self, S, var='a'):
             ValueError: S must be a list of primes
         """
         if self.root is None:
-            if os.path.exists(JONESDATA + "/jones.sobj"):
-                self.root = load(JONESDATA + "/jones.sobj")
-            else:
-                raise PackageNotFoundError("database_jones_numfield")
+            self.root = load(DatabaseJones().absolute_path())
         try:
             S = list(S)
         except TypeError:
diff --git a/src/sage/features/__init__.py b/src/sage/features/__init__.py
@@ -252,7 +252,7 @@ class FeatureNotPresentError(RuntimeError):
     def __init__(self, feature, reason=None, resolution=None):
         self.feature = feature
         self.reason = reason
-        self.resolution = resolution
+        self.resolution = resolution or feature.resolution()
 
     def __str__(self):
         r"""
diff --git a/src/sage/features/databases.py b/src/sage/features/databases.py
@@ -32,3 +32,25 @@ def __init__(self, name="cremona", spkg="database_cremona_ellcurve"):
                             filename=os.path.join("cremona", filename),
                             spkg=spkg,
                             url="https://github.com/JohnCremona/ecdata")
+
+class DatabaseJones(StaticFile):
+    r"""
+    A :class:`Feature` which describes the presence of John Jones's tables of number fields.
+
+    EXAMPLES::
+
+        sage: from sage.features.databases import DatabaseJones
+        sage: bool(DatabaseJones().is_present())  # optional: database_jones_numfield
+        True
+    """
+    def __init__(self):
+        r"""
+        TESTS::
+
+            sage: from sage.features.databases import DatabaseJones
+            sage: isinstance(DatabaseJones(), DatabaseJones)
+            True
+        """
+        StaticFile.__init__(self, "John Jones's tables of number fields",
+                            filename='jones/jones.sobj',
+                            spkg="database_jones_numfield")
diff --git a/src/sage/game_theory/normal_form_game.py b/src/sage/game_theory/normal_form_game.py
@@ -1765,9 +1765,10 @@ def _solve_lrs(self, maximization=True):
             process = Popen(['lrsnash', g1_name, g2_name],
                     stdout=PIPE,
                     stderr=PIPE)
-        except OSError:
-            from sage.misc.package import PackageNotFoundError
-            raise PackageNotFoundError("lrslib")
+        except OSError as e:
+            from sage.features.lrs import Lrs
+            from sage.features import FeatureNotPresentError
+            raise FeatureNotPresentError(Lrs(), reason=f'Calling lrsnash failed with {e}')
 
         lrs_output = [bytes_to_str(row) for row in process.stdout]
         process.terminate()
diff --git a/src/sage/misc/package.py b/src/sage/misc/package.py
@@ -49,13 +49,8 @@
 import os
 import subprocess
 import sys
-try:
-    # Python 3.3+
-    from urllib.request import urlopen
-    from urllib.error import URLError
-except ImportError:
-    # Python 2.7
-    from urllib2 import urlopen, URLError
+from urllib.request import urlopen
+from urllib.error import URLError
 
 DEFAULT_PYPI = 'https://pypi.org/pypi'
 
@@ -546,14 +541,40 @@ class PackageNotFoundError(RuntimeError):
     - The required optional package is installed, but the relevant
       interface to that package is unable to detect the package.
 
+    Raising a ``PackageNotFoundError`` is deprecated.  Use
+    :class:`sage.features.FeatureNotPresentError` instead.
+
+    User code can continue to catch ``PackageNotFoundError`` exceptions
+    for compatibility with older versions of the Sage library.
+    This does not cause deprecation warnings.
+
     EXAMPLES::
 
         sage: from sage.misc.package import PackageNotFoundError
-        sage: raise PackageNotFoundError("my_package")
-        Traceback (most recent call last):
-        ...
-        PackageNotFoundError: the package 'my_package' was not found. You can install it by running 'sage -i my_package' in a shell
+        sage: try:
+        ....:     pass
+        ....: except PackageNotFoundError:
+        ....:     pass
+
     """
+
+    def __init__(self, *args):
+        """
+        TESTS::
+
+            sage: from sage.misc.package import PackageNotFoundError
+            sage: raise PackageNotFoundError("my_package")
+            Traceback (most recent call last):
+            ...
+            PackageNotFoundError: the package 'my_package' was not found. You can install it by running 'sage -i my_package' in a shell
+        """
+        super().__init__(*args)
+        # We do not deprecate the whole class because we want
+        # to allow user code to handle this exception without causing
+        # a deprecation warning.
+        from sage.misc.superseded import deprecation
+        deprecation(30607, "Instead of raising PackageNotFoundError, raise sage.features.FeatureNotPresentError")
+
     def __str__(self):
         """
         Return the actual error message.
@@ -562,6 +583,7 @@ def __str__(self):
 
             sage: from sage.misc.package import PackageNotFoundError
             sage: str(PackageNotFoundError("my_package"))
+            doctest:warning...
             "the package 'my_package' was not found. You can install it by running 'sage -i my_package' in a shell"
         """
         return ("the package {0!r} was not found. "
