remove ability to pass multiple keys to extract_as_list

This makes the typing annotations basically impossible to get right, but
if we only have one key then it's easy. Fortunately python provides
comprehensions, so we don't even need the ability to pass multiple keys,
we can just [extract_as_list(kwargs, c) for c in ('a', 'b', 'c')] and
get the same result.

mesonbuild/build.py

@@ -827,8 +827,7 @@ just like those detected with the dependency() function.''')
             self.link_whole(linktarget)
 
         c_pchlist, cpp_pchlist, clist, cpplist, cudalist, cslist, valalist,  objclist, objcpplist, fortranlist, rustlist \
-            = extract_as_list(kwargs, 'c_pch', 'cpp_pch', 'c_args', 'cpp_args', 'cuda_args', 'cs_args', 'vala_args', 'objc_args',
-                              'objcpp_args', 'fortran_args', 'rust_args')
+            = [extract_as_list(kwargs, c) for c in ['c_pch', 'cpp_pch', 'c_args', 'cpp_args', 'cuda_args', 'cs_args', 'vala_args', 'objc_args', 'objcpp_args', 'fortran_args', 'rust_args']]
 
         self.add_pch('c', c_pchlist)
         self.add_pch('cpp', cpp_pchlist)
@@ -2161,7 +2160,7 @@ class CustomTarget(Target):
             self.build_always_stale = kwargs['build_always_stale']
         if not isinstance(self.build_always_stale, bool):
             raise InvalidArguments('Argument build_always_stale must be a boolean.')
-        extra_deps, depend_files = extract_as_list(kwargs, 'depends', 'depend_files', pop = False)
+        extra_deps, depend_files = [extract_as_list(kwargs, c, pop=False) for c in ['depends', 'depend_files']]
         for ed in extra_deps:
             while hasattr(ed, 'held_object'):
                 ed = ed.held_object

mesonbuild/dependencies/boost.py

@@ -272,7 +272,7 @@ class BoostDependency(ExternalDependency):
         self.boost_root = None
 
         # Extract and validate modules
-        self.modules = mesonlib.extract_as_list(kwargs, 'modules')
+        self.modules = mesonlib.extract_as_list(kwargs, 'modules')  # type: T.List[str]
         for i in self.modules:
             if not isinstance(i, str):
                 raise DependencyException('Boost module argument is not a string.')

mesonbuild/mesonlib.py

@@ -1075,22 +1075,15 @@ def listify(item: T.Any, flatten: bool = True) -> T.List[T.Any]:
     return result
 
 
-def extract_as_list(dict_object: T.Dict[_T, _U], *keys: _T, pop: bool = False,
-                    flatten: bool = True) -> T.List[T.Union[_U, T.List[_U]]]:
+def extract_as_list(dict_object: T.Dict[_T, _U], key: _T, pop: bool = False) -> T.List[_U]:
     '''
     Extracts all values from given dict_object and listifies them.
     '''
-    result = []  # type: T.List[T.Union[_U, T.List[_U]]]
     fetch = dict_object.get
     if pop:
         fetch = dict_object.pop
     # If there's only one key, we don't return a list with one element
-    if len(keys) == 1:
-        return listify(fetch(keys[0], []), flatten=True)
-    # Return a list of values corresponding to *keys
-    for key in keys:
-        result.append(listify(fetch(key, []), flatten=True))
-    return result
+    return listify(fetch(key, []), flatten=True)
 
 
 def typeslistify(item: 'T.Union[_T, T.Sequence[_T]]',

mesonbuild/modules/gnome.py

@@ -98,7 +98,7 @@ class GnomeModule(ExtensionModule):
 
         cmd = ['glib-compile-resources', '@INPUT@']
 
-        source_dirs, dependencies = mesonlib.extract_as_list(kwargs, 'source_dir', 'dependencies', pop=True)
+        source_dirs, dependencies = [mesonlib.extract_as_list(kwargs, c, pop=True) for c in  ['source_dir', 'dependencies']]
 
         if len(args) < 2:
             raise MesonException('Not enough arguments; the name of the resource '

mesonbuild/modules/qt.py

@@ -123,7 +123,7 @@ class QtBaseModule(ExtensionModule):
     @permittedKwargs({'moc_headers', 'moc_sources', 'uic_extra_arguments', 'moc_extra_arguments', 'rcc_extra_arguments', 'include_directories', 'dependencies', 'ui_files', 'qresources', 'method'})
     def preprocess(self, state, args, kwargs):
         rcc_files, ui_files, moc_headers, moc_sources, uic_extra_arguments, moc_extra_arguments, rcc_extra_arguments, sources, include_directories, dependencies \
-            = extract_as_list(kwargs, 'qresources', 'ui_files', 'moc_headers', 'moc_sources', 'uic_extra_arguments', 'moc_extra_arguments', 'rcc_extra_arguments', 'sources', 'include_directories', 'dependencies', pop = True)
+            = [extract_as_list(kwargs, c, pop=True) for c in ['qresources', 'ui_files', 'moc_headers', 'moc_sources', 'uic_extra_arguments', 'moc_extra_arguments', 'rcc_extra_arguments', 'sources', 'include_directories', 'dependencies']]
         sources += args[1:]
         method = kwargs.get('method', 'auto')
         self._detect_tools(state.environment, method)
@@ -202,7 +202,7 @@ class QtBaseModule(ExtensionModule):
     @FeatureNew('qt.compile_translations', '0.44.0')
     @permittedKwargs({'ts_files', 'install', 'install_dir', 'build_by_default', 'method'})
     def compile_translations(self, state, args, kwargs):
-        ts_files, install_dir = extract_as_list(kwargs, 'ts_files', 'install_dir', pop=True)
+        ts_files, install_dir = [extract_as_list(kwargs, c, pop=True) for c in  ['ts_files', 'install_dir']]
         self._detect_tools(state.environment, kwargs.get('method', 'auto'))
         translations = []
         for ts in ts_files:

run_unittests.py

@@ -706,17 +706,15 @@ class InternalTests(unittest.TestCase):
         self.assertEqual(kwargs, {'sources': [1, 2, 3]})
         self.assertEqual([1, 2, 3], extract(kwargs, 'sources', pop=True))
         self.assertEqual(kwargs, {})
+
         # Test unholding
         holder3 = ObjectHolder(3)
         kwargs = {'sources': [1, 2, holder3]}
         self.assertEqual(kwargs, {'sources': [1, 2, holder3]})
-        # Test listification
-        kwargs = {'sources': [1, 2, 3], 'pch_sources': [4, 5, 6]}
-        self.assertEqual([[1, 2, 3], [4, 5, 6]], extract(kwargs, 'sources', 'pch_sources'))
 
         # flatten nested lists
         kwargs = {'sources': [1, [2, [3]]]}
-        self.assertEqual([1, 2, 3], extract(kwargs, 'sources', flatten=True))
+        self.assertEqual([1, 2, 3], extract(kwargs, 'sources'))
 
     def test_pkgconfig_module(self):