diff options
| -rw-r--r-- | lib/spack/spack/spec.py | 64 |
1 files changed, 41 insertions, 23 deletions
diff --git a/lib/spack/spack/spec.py b/lib/spack/spack/spec.py index 341e266493..489e1135af 100644 --- a/lib/spack/spack/spec.py +++ b/lib/spack/spack/spec.py @@ -770,10 +770,6 @@ class ForwardQueryToPackage(object): instance """ self.attribute_name = attribute_name - # Turn the default handler into a function with the right - # signature that always returns None - if default_handler is None: - default_handler = lambda descriptor, spec, cls: None self.default = default_handler def __get__(self, instance, cls): @@ -792,8 +788,11 @@ class ForwardQueryToPackage(object): The first call that produces a value will stop the chain. - If no call can handle the request or a None value is produced, - then AttributeError is raised. + If no call can handle the request then AttributeError is raised with a + message indicating that no relevant attribute exists. + If a call returns None, an AttributeError is raised with a message + indicating a query failure, e.g. that library files were not found in a + 'libs' query. """ pkg = instance.package try: @@ -814,34 +813,53 @@ class ForwardQueryToPackage(object): # Try to get the generic method from Package callbacks_chain.append(lambda: getattr(pkg, self.attribute_name)) # Final resort : default callback - callbacks_chain.append(lambda: self.default(self, instance, cls)) + if self.default is not None: + callbacks_chain.append(lambda: self.default(self, instance, cls)) # Trigger the callbacks in order, the first one producing a # value wins value = None + message = None for f in callbacks_chain: try: value = f() + # A callback can return None to trigger an error indicating + # that the query failed. + if value is None: + msg = "Query of package '{name}' for '{attrib}' failed\n" + msg += "\tprefix : {spec.prefix}\n" + msg += "\tspec : {spec}\n" + msg += "\tqueried as : {query.name}\n" + msg += "\textra parameters : {query.extra_parameters}" + message = msg.format( + name=pkg.name, attrib=self.attribute_name, + spec=instance, query=instance.last_query) + else: + return value break except AttributeError: pass - # 'None' value raises AttributeError : this permits to 'disable' - # the call in a particular package by returning None from the - # queried attribute, or will trigger an exception if things - # searched for were not found - if value is None: - fmt = '\'{name}\' package has no relevant attribute \'{query}\'\n' # NOQA: ignore=E501 - fmt += '\tspec : \'{spec}\'\n' - fmt += '\tqueried as : \'{spec.last_query.name}\'\n' - fmt += '\textra parameters : \'{spec.last_query.extra_parameters}\'\n' # NOQA: ignore=E501 - message = fmt.format( - name=pkg.name, - query=self.attribute_name, - spec=instance - ) + # value is 'None' + if message is not None: + # Here we can use another type of exception. If we do that, the + # unit test 'test_getitem_exceptional_paths' in the file + # lib/spack/spack/test/spec_dag.py will need to be updated to match + # the type. raise AttributeError(message) - - return value + # 'None' value at this point means that there are no appropriate + # properties defined and no default handler, or that all callbacks + # raised AttributeError. In this case, we raise AttributeError with an + # appropriate message. + fmt = '\'{name}\' package has no relevant attribute \'{query}\'\n' # NOQA: ignore=E501 + fmt += '\tspec : \'{spec}\'\n' + fmt += '\tqueried as : \'{spec.last_query.name}\'\n' + fmt += '\textra parameters : \'{spec.last_query.extra_parameters}\'\n' # NOQA: ignore=E501 + message = fmt.format( + name=pkg.name, + query=self.attribute_name, + spec=instance + ) + raise AttributeError(message) def __set__(self, instance, value): cls_name = type(instance).__name__ |