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Static type checking with mypy

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This does introduce some not-so-nice things, like having to annotate each
`__init__` function with `-> None`. However, the benefits of having static
type checking in a complex bit of software like BAT outweigh the downsides.
This commit is contained in:
Sybren A. Stüvel
2018-03-09 11:09:47 +01:00
parent 632d01334c
commit fdbbc3a20d
18 changed files with 117 additions and 82 deletions
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blender_asset_tracer/blendfile/__init__.py
+43 -34
View File
@@ -22,14 +22,13 @@
import atexit
import collections
import functools
import gzip
import logging
import os
import struct
import pathlib
import tempfile
import functools
import typing
from . import exceptions, dna_io, dna, header
@@ -40,8 +39,9 @@ log = logging.getLogger(__name__)
FILE_BUFFER_SIZE = 1024 * 1024
BLENDFILE_MAGIC = b'BLENDER'
GZIP_MAGIC = b'\x1f\x8b'
BFBList = typing.List['BlendFileBlock']
_cached_bfiles = {}
_cached_bfiles = {} # type: typing.Dict[pathlib.Path, BlendFile]
def open_cached(path: pathlib.Path, mode='rb', assert_cached=False) -> 'BlendFile':
@@ -94,7 +94,7 @@ class BlendFile:
"""
log = log.getChild('BlendFile')
def __init__(self, path: pathlib.Path, mode='rb'):
def __init__(self, path: pathlib.Path, mode='rb') -> None:
"""Create a BlendFile instance for the blend file at the path.
Opens the file for reading or writing pending on the access. Compressed
@@ -106,22 +106,21 @@ class BlendFile:
self.filepath = path
self.raw_filepath = path
self._is_modified = False
self.fileobj = None # type: typing.IO[bytes]
self._open_file(path, mode)
self.blocks = [] # BlendFileBlocks, in disk order.
self.code_index = collections.defaultdict(list)
self.structs = []
self.sdna_index_from_id = {}
self.block_from_addr = {}
self.blocks = [] # type: BFBList
"""BlendFileBlocks of this file, in disk order."""
try:
self.header = header.BlendFileHeader(self.fileobj, self.raw_filepath)
self.block_header_struct = self.header.create_block_header_struct()
self._load_blocks()
except Exception:
self.fileobj.close()
raise
self.code_index = collections.defaultdict(list) # type: typing.Dict[bytes, BFBList]
self.structs = [] # type: typing.List[dna.Struct]
self.sdna_index_from_id = {} # type: typing.Dict[bytes, int]
self.block_from_addr = {} # type: typing.Dict[int, BlendFileBlock]
self.header = header.BlendFileHeader(self.fileobj, self.raw_filepath)
self.block_header_struct = self.header.create_block_header_struct()
self._load_blocks()
def _open_file(self, path: pathlib.Path, mode: str):
"""Open a blend file, decompressing if necessary.
@@ -134,7 +133,10 @@ class BlendFile:
correct magic bytes.
"""
fileobj = path.open(mode, buffering=FILE_BUFFER_SIZE)
if 'b' not in mode:
raise ValueError('Only binary modes are supported, not %r' % mode)
fileobj = path.open(mode, buffering=FILE_BUFFER_SIZE) # typing.IO[bytes]
fileobj.seek(0, os.SEEK_SET)
magic = fileobj.read(len(BLENDFILE_MAGIC))
@@ -171,13 +173,16 @@ class BlendFile:
def _load_blocks(self):
"""Read the blend file to load its DNA structure to memory."""
self.structs.clear()
self.sdna_index_from_id.clear()
while True:
block = BlendFileBlock(self)
if block.code == b'ENDB':
break
if block.code == b'DNA1':
self.structs, self.sdna_index_from_id = self.decode_structs(block)
self.decode_structs(block)
else:
self.fileobj.seek(block.size, os.SEEK_CUR)
@@ -270,6 +275,10 @@ class BlendFile:
DNACatalog is a catalog of all information in the DNA1 file-block
"""
self.log.debug("building DNA catalog")
# Get some names in the local scope for faster access.
structs = self.structs
sdna_index_from_id = self.sdna_index_from_id
endian = self.header.endian
shortstruct = endian.USHORT
shortstruct2 = endian.USHORT2
@@ -282,8 +291,6 @@ class BlendFile:
data = self.fileobj.read(block.size)
types = []
typenames = []
structs = []
sdna_index_from_id = {}
offset = 8
names_len = intstruct.unpack_from(data, offset)[0]
@@ -346,8 +353,6 @@ class BlendFile:
dna_struct.append_field(field)
dna_offset += dna_size
return structs, sdna_index_from_id
def abspath(self, relpath: bpathlib.BlendPath) -> bpathlib.BlendPath:
"""Construct an absolute path from a blendfile-relative path."""
@@ -391,7 +396,7 @@ class BlendFileBlock:
old_structure = struct.Struct(b'4sI')
"""old blend files ENDB block structure"""
def __init__(self, bfile: BlendFile):
def __init__(self, bfile: BlendFile) -> None:
self.bfile = bfile
# Defaults; actual values are set by interpreting the block header.
@@ -406,7 +411,7 @@ class BlendFileBlock:
Points to the data after the block header.
"""
self.endian = bfile.header.endian
self._id_name = ... # see the id_name property
self._id_name = ... # type: typing.Union[None, ellipsis, bytes]
header_struct = bfile.block_header_struct
data = bfile.fileobj.read(header_struct.size)
@@ -448,7 +453,7 @@ class BlendFileBlock:
def __hash__(self) -> int:
return hash((self.code, self.addr_old, self.bfile.filepath))
def __eq__(self, other: 'BlendFileBlock') -> bool:
def __eq__(self, other: object) -> bool:
if not isinstance(other, BlendFileBlock):
return False
return (self.code == other.code and
@@ -487,7 +492,10 @@ class BlendFileBlock:
self._id_name = self[b'id', b'name']
except KeyError:
self._id_name = None
return self._id_name
# TODO(Sybren): figure out how to let mypy know self._id_name cannot
# be ellipsis at this point.
return self._id_name # type: ignore
def refine_type_from_index(self, sdna_index: int):
"""Change the DNA Struct associated with this block.
@@ -514,7 +522,7 @@ class BlendFileBlock:
sdna_index = self.bfile.sdna_index_from_id[dna_type_id]
self.refine_type_from_index(sdna_index)
def abs_offset(self, path: dna.FieldPath) -> (int, int):
def abs_offset(self, path: dna.FieldPath) -> typing.Tuple[int, int]:
"""Compute the absolute file offset of the field.
:returns: tuple (offset in bytes, length of array in items)
@@ -563,18 +571,19 @@ class BlendFileBlock:
default=...,
null_terminated=True,
as_str=True,
) -> typing.Iterator[typing.Tuple[bytes, typing.Any]]:
) -> typing.Iterator[typing.Tuple[dna.FieldPath, typing.Any]]:
"""Generator, yields (path, property value) tuples.
If a property cannot be decoded, a string representing its DNA type
name is used as its value instead, between pointy brackets.
"""
path_full = path # type: dna.FieldPath
if path_root:
path_full = (
(path_root if type(path_root) is tuple else (path_root,)) +
(path if type(path) is tuple else (path,)))
else:
path_full = path
if isinstance(path_root, bytes):
path_root = (path_root,)
if isinstance(path, bytes):
path = (path,)
path_full = tuple(path_root) + tuple(path)
try:
# Try accessing as simple property
@@ -615,7 +624,7 @@ class BlendFileBlock:
hsh = zlib.adler32(str(value).encode(), hsh)
return hsh
def set(self, path: dna.FieldPath, value):
def set(self, path: bytes, value):
dna_struct = self.bfile.structs[self.sdna_index]
self.bfile.mark_modified()
self.bfile.fileobj.seek(self.file_offset, os.SEEK_SET)