Use f-strings instead of string concatenation (#4675)

Author: akx

boto3/docs/__init__.py

@@ -45,7 +45,7 @@ def generate_docs(root_dir, session):
             service_name, session, services_doc_path
         ).document_service()
         service_doc_path = os.path.join(
-            services_doc_path, service_name + '.rst'
+            services_doc_path, f"{service_name}.rst"
         )
         with open(service_doc_path, 'wb') as f:
             f.write(docs)

boto3/docs/service.py

@@ -190,7 +190,7 @@ def _document_resources(self, section):
 
     def _get_example_file(self):
         return os.path.realpath(
-            os.path.join(self.EXAMPLE_PATH, self._service_name + '.rst')
+            os.path.join(self.EXAMPLE_PATH, f"{self._service_name}.rst")
         )
 
     def _document_examples(self, section):

boto3/dynamodb/conditions.py

@@ -311,10 +311,10 @@ def __init__(self):
         self._value_placeholder = 'v'
 
     def _get_name_placeholder(self):
-        return '#' + self._name_placeholder + str(self._name_count)
+        return f"#{self._name_placeholder}{self._name_count}"
 
     def _get_value_placeholder(self):
-        return ':' + self._value_placeholder + str(self._value_count)
+        return f":{self._value_placeholder}{self._value_count}"
 
     def reset(self):
         """Resets the placeholder name and values"""
@@ -451,7 +451,7 @@ def _build_value_placeholder(
             # Assuming the values are grouped by parenthesis.
             # IN is the currently the only one that uses this so it maybe
             # needed to be changed in future.
-            return '(' + ', '.join(placeholder_list) + ')'
+            return f"({', '.join(placeholder_list)})"
         # Otherwise, treat the value as a single value that needs only
         # one placeholder.
         else:

boto3/resources/base.py

@@ -104,7 +104,7 @@ def __init__(self, *args, **kwargs):
         # Allow setting identifiers as positional arguments in the order
         # in which they were defined in the ResourceJSON.
         for i, value in enumerate(args):
-            setattr(self, '_' + self.meta.identifiers[i], value)
+            setattr(self, f"_{self.meta.identifiers[i]}", value)
 
         # Allow setting identifiers via keyword arguments. Here we need
         # extra logic to ignore other keyword arguments like ``client``.
@@ -115,23 +115,19 @@ def __init__(self, *args, **kwargs):
             if name not in self.meta.identifiers:
                 raise ValueError(f'Unknown keyword argument: {name}')
 
-            setattr(self, '_' + name, value)
+            setattr(self, f"_{name}", value)
 
         # Validate that all identifiers have been set.
         for identifier in self.meta.identifiers:
             if getattr(self, identifier) is None:
                 raise ValueError(f'Required parameter {identifier} not set')
 
     def __repr__(self):
-        identifiers = []
-        for identifier in self.meta.identifiers:
-            identifiers.append(
-                f'{identifier}={repr(getattr(self, identifier))}'
-            )
-        return "{}({})".format(
-            self.__class__.__name__,
-            ', '.join(identifiers),
-        )
+        identifiers = [
+            f'{identifier}={repr(getattr(self, identifier))}'
+            for identifier in self.meta.identifiers
+        ]
+        return f"{self.__class__.__name__}({', '.join(identifiers)})"
 
     def __eq__(self, other):
         # Should be instances of the same resource class

boto3/resources/factory.py

@@ -145,7 +145,7 @@ def load_from_definition(
         cls_name = resource_name
         if service_context.service_name == resource_name:
             cls_name = 'ServiceResource'
-        cls_name = service_context.service_name + '.' + cls_name
+        cls_name = f"{service_context.service_name}.{cls_name}"
 
         base_classes = [ServiceResource]
         if self._emitter is not None:
@@ -325,7 +325,7 @@ def get_identifier(self):
             # identifiers have a value ``None``. If any are ``None``,
             # a more informative user error than a generic AttributeError
             # is raised.
-            return getattr(self, '_' + identifier.name, None)
+            return getattr(self, f"_{identifier.name}", None)
 
         get_identifier.__name__ = str(identifier.name)
         get_identifier.__doc__ = docstring.IdentifierDocstring(
@@ -344,7 +344,7 @@ def _create_identifier_alias(
         """
 
         def get_identifier(self):
-            return getattr(self, '_' + identifier.name, None)
+            return getattr(self, f"_{identifier.name}", None)
 
         get_identifier.__name__ = str(identifier.member_name)
         get_identifier.__doc__ = docstring.AttributeDocstring(

boto3/resources/model.py

@@ -367,8 +367,8 @@ def _load_name_with_category(self, names, name, category, snake_case=True):
 
         if name in names:
             logger.debug('Renaming %s %s %s', self.name, category, name)
-            self._renamed[(category, name)] = name + '_' + category
-            name += '_' + category
+            self._renamed[(category, name)] = f"{name}_{category}"
+            name += f"_{category}"
 
             if name in names:
                 # This isn't good, let's raise instead of trying to keep

boto3/resources/params.py

@@ -132,7 +132,7 @@ def build_param_structure(params, target, value, index=None):
                 else:
                     # We have an explicit index
                     index = int(result.group(1))
-                    part = part[: -len(str(index) + '[]')]
+                    part = part[: -len(f"{index}[]")]
             else:
                 # Index will be set after we know the proper part
                 # name and that it's a list instance.

boto3/s3/transfer.py

@@ -456,9 +456,7 @@ def upload_file(
         # client error.
         except ClientError as e:
             raise S3UploadFailedError(
-                "Failed to upload {} to {}: {}".format(
-                    filename, '/'.join([bucket, key]), e
-                )
+                f"Failed to upload {filename} to {bucket}/{key}: {e}"
             )
 
     def download_file(

boto3/session.py

@@ -72,7 +72,7 @@ def __init__(
         if self._session.user_agent_name == 'Botocore':
             botocore_info = f'Botocore/{self._session.user_agent_version}'
             if self._session.user_agent_extra:
-                self._session.user_agent_extra += ' ' + botocore_info
+                self._session.user_agent_extra += f" {botocore_info}"
             else:
                 self._session.user_agent_extra = botocore_info
             self._session.user_agent_name = 'Boto3'