Merge pull request #4572 from mwichmann/env/dump-multi

Enhancement: Dump() takes multiple args now

Author: bdbaddog

CHANGES.txt

@@ -18,6 +18,15 @@ RELEASE  VERSION/DATE TO BE FILLED IN LATER
       will benefit from `TypeGuard`/`TypeIs`, to produce intellisense similar
       to using `isinstance` directly.
 
+  From Mats Wichmann:
+    - env.Dump() now considers the "key" positional argument to be a varargs
+      type (zero, one or many). However called, it returns a serialized
+      result that looks like a dict. Previously, only one "key" was
+      accepted. and unlike the zero-args case, it was be serialized
+      to a string containing the value without the key. For example, if
+      "print(repr(env.Dump('CC'))" previously returned "'gcc'", it will now
+      return "{'CC': 'gcc'}".
+
 
 RELEASE 4.8.0 -  Sun, 07 Jul 2024 17:22:20 -0700
 

RELEASE.txt

@@ -26,8 +26,15 @@ DEPRECATED FUNCTIONALITY
 CHANGED/ENHANCED EXISTING FUNCTIONALITY
 ---------------------------------------
 
-- List modifications to existing features, where the previous behavior
-  wouldn't actually be considered a bug
+- env.Dump() previously accepted a single optional "key" argument.
+  It now accepts any number of optional "key" arguments; any supplied
+  keys will be serialized with their values in a Python dict style.
+  As a result there is a small change in behavior: if a *single* key
+  argument is given, where it previously would return a string containing
+  just the value, now it will return a string that looks like a dictionary
+  including the key.  For example, from "'gcc'" to "{'CC': 'gcc'}".
+  This should not have any impact as the result of calling Dump is
+  intended for diagnostic output, not for use by other interfaces.
 
 FIXES
 -----
@@ -38,8 +45,8 @@ IMPROVEMENTS
 ------------
 
 - List improvements that wouldn't be visible to the user in the
-  documentation:  performance improvements (describe the circumstances
-  under which they would be observed), or major code cleanups
+documentation:  performance improvements (describe the circumstances
+under which they would be observed), or major code cleanups
 
 PACKAGING
 ---------

SCons/Environment.py

@@ -1694,28 +1694,37 @@ def Dictionary(self, *args):
         return dlist
 
 
-    def Dump(self, key: Optional[str] = None, format: str = 'pretty') -> str:
-        """ Returns a dump of serialized construction variables.
+    def Dump(self, *key: str, format: str = 'pretty') -> str:
+        """Return string of serialized construction variables.
 
-        The display formats are intended for humaan readers when
-        debugging - none of the supported formats produce a result that
-        SCons itself can directly make use of. Objects that cannot
-        directly be represented get a placeholder like
-        ``<function foo at 0x123456>`` or ``<<non-serializable: function>>``.
+        Produces a "pretty" output of a dictionary of selected
+        construction variables, or all of them. The display *format* is
+        selectable. The result is intended for human consumption (e.g,
+        to print), mainly when debugging.  Objects that cannot directly be
+        represented get a placeholder like ``<function foo at 0x123456>``
+        (pretty-print) or ``<<non-serializable: function>>`` (JSON).
 
         Args:
-           key: if ``None``, format the whole dict of variables,
-              else format just the value of *key*.
+           key: if omitted, format the whole dict of variables,
+              else format *key*(s) with the corresponding values.
            format: specify the format to serialize to. ``"pretty"`` generates
              a pretty-printed string, ``"json"`` a JSON-formatted string.
 
         Raises:
            ValueError: *format* is not a recognized serialization format.
+
+        .. versionchanged:: NEXT_VERSION
+           *key* is no longer limited to a single construction variable name.
+           If *key* is supplied, a formatted dictionary is generated like the
+           no-arg case - previously a single *key* displayed just the value.
         """
-        if key:
-            cvars = self.Dictionary(key)
-        else:
+        if not key:
             cvars = self.Dictionary()
+        elif len(key) == 1:
+            dkey = key[0]
+            cvars = {dkey: self[dkey]}
+        else:
+            cvars = dict(zip(key, self.Dictionary(*key)))
 
         fmt = format.lower()
 
@@ -1735,14 +1744,15 @@ def Dump(self, key: Optional[str] = None, format: str = 'pretty') -> str:
 
             class DumpEncoder(json.JSONEncoder):
                 """SCons special json Dump formatter."""
+
                 def default(self, obj):
                     if isinstance(obj, (UserList, UserDict)):
                         return obj.data
                     return f'<<non-serializable: {type(obj).__qualname__}>>'
 
             return json.dumps(cvars, indent=4, cls=DumpEncoder, sort_keys=True)
-        else:
-            raise ValueError("Unsupported serialization format: %s." % fmt)
+
+        raise ValueError("Unsupported serialization format: %s." % fmt)
 
 
     def FindIxes(self, paths: Sequence[str], prefix: str, suffix: str) -> Optional[str]:

SCons/Environment.xml

@@ -1692,56 +1692,74 @@ for more information.
 
 <scons_function name="Dump">
 <arguments signature="env">
-([key], [format])
+([key, ...], [format=])
 </arguments>
 <summary>
 <para>
-Serializes &consvars; to a string.
+Serializes &consvars; from the current &consenv;
+to a string.
 The method supports the following formats specified by
-<parameter>format</parameter>:
+<parameter>format</parameter>,
+which must be used a a keyword argument:
+</para>
 <variablelist>
 <varlistentry>
 <term><literal>pretty</literal></term>
 <listitem>
 <para>
-Returns a pretty printed representation of the environment (if
-<parameter>format</parameter>
-is not specified, this is the default).
+Returns a pretty-printed representation of the variables
+(this is the default).
+The variables will be presented in &Python; dict form.
 </para>
 </listitem>
 </varlistentry>
 <varlistentry>
 <term><literal>json</literal></term>
 <listitem>
 <para>
-Returns a JSON-formatted string representation of the environment.
+Returns a JSON-formatted string representation of the variables.
+The variables will be presented as a JSON object literal,
+the JSON equivalent of a &Python; dict.
 </para>
 </listitem>
 </varlistentry>
 </variablelist>
 
-If <varname>key</varname> is
-<constant>None</constant> (the default) the entire
-dictionary of &consvars; is serialized.
-If supplied, it is taken as the name of a &consvar;
-whose value is serialized.
+<para>
+If no <varname>key</varname> is supplied,
+all the &consvars; are serialized.
+If one or more keys are supplied,
+only those keys and their values are serialized.
+</para>
+
+<para>
+<emphasis>Changed in NEXT_VERSION</emphasis>:
+More than one <parameter>key</parameter> can be specified.
+The returned string always looks like a dict (or JSON equivalent);
+previously a single key serialized only the value,
+not the key with the value.
 </para>
 
 <para>
 This SConstruct:
 </para>
 
 <example_commands>
-env=Environment()
+env = Environment()
 print(env.Dump('CCCOM'))
+print(env.Dump('CC', 'CCFLAGS', format='json'))
 </example_commands>
 
 <para>
-will print:
+will print something like:
 </para>
 
 <example_commands>
-'$CC -c -o $TARGET $CCFLAGS $CPPFLAGS $_CPPDEFFLAGS $_CPPINCFLAGS $SOURCES'
+{'CCCOM': '$CC -o $TARGET -c $CFLAGS $CCFLAGS $_CCCOMCOM $SOURCES'}
+{
+    "CC": "gcc",
+    "CCFLAGS": []
+}
 </example_commands>
 
 <para>
@@ -1754,7 +1772,7 @@ print(env.Dump())
 </example_commands>
 
 <para>
-will print:
+will print something like:
 </para>
 <example_commands>
 { 'AR': 'ar',
@@ -1765,6 +1783,7 @@ will print:
   'ASFLAGS': [],
   ...
 </example_commands>
+
 </summary>
 </scons_function>
 

SCons/EnvironmentTests.py

@@ -3176,24 +3176,42 @@ def test_NoClean(self) -> None:
 
     def test_Dump(self) -> None:
         """Test the Dump() method"""
-
         env = self.TestEnvironment(FOO='foo', FOOFLAGS=CLVar('--bar --baz'))
-        assert env.Dump('FOO') == "'foo'", env.Dump('FOO')
-        assert len(env.Dump()) > 200, env.Dump()    # no args version
 
-        assert env.Dump('FOO', 'json') == '"foo"'    # JSON key version
-        expect = """[\n    "--bar",\n    "--baz"\n]"""
-        self.assertEqual(env.Dump('FOOFLAGS', 'json'), expect)
-        import json
-        env_dict = json.loads(env.Dump(format = 'json'))
-        assert env_dict['FOO'] == 'foo'    # full JSON version
+        # changed in NEXT_VERSION: single arg now displays as a dict,
+        #   not a bare value; more than one arg is allowed.
+        with self.subTest():  # one-arg version
+            self.assertEqual(env.Dump('FOO'), "{'FOO': 'foo'}")
+
+        with self.subTest():  # multi-arg version
+            expect = "{'FOO': 'foo', 'FOOFLAGS': ['--bar', '--baz']}"
+            self.assertEqual(env.Dump('FOO', 'FOOFLAGS'), expect)
+
+        with self.subTest():  # no-arg version
+            self.assertGreater(len(env.Dump()), 200)
+
+        with self.subTest():  # one-arg JSON version, simple value
+            expect = '{\n    "FOO": "foo"\n}'
+            self.assertEqual(env.Dump('FOO', format='json'), expect)
+
+        with self.subTest():  # one-arg JSON version, list value
+            expect = '{\n    "FOOFLAGS": [\n        "--bar",\n        "--baz"\n    ]\n}'
+            self.assertEqual(env.Dump('FOOFLAGS', format='json'), expect)
+
+        with self.subTest():  # multi--arg JSON version, list value
+            expect = '{\n    "FOO": "foo",\n    "FOOFLAGS": [\n        "--bar",\n        "--baz"\n    ]\n}'
+            self.assertEqual(env.Dump('FOO', 'FOOFLAGS', format='json'), expect)
+
+        with self.subTest():  # full JSON version
+            import json
+            env_dict = json.loads(env.Dump(format='json'))
+            self.assertEqual(env_dict['FOO'], 'foo')
+
+        with self.subTest():  # unsupported format type
+            with self.assertRaises(ValueError) as cm:
+                env.Dump(format='markdown')
+            self.assertEqual(str(cm.exception), "Unsupported serialization format: markdown.")
 
-        try:
-            env.Dump(format = 'markdown')
-        except ValueError as e:
-            assert str(e) == "Unsupported serialization format: markdown."
-        else:
-            self.fail("Did not catch expected ValueError.")
 
     def test_Environment(self) -> None:
         """Test the Environment() method"""