Address TODO in pyproject/tables

src/poetry/core/pyproject/tables.py

@@ -1,6 +1,6 @@
 from __future__ import annotations
 
-from contextlib import suppress
+from functools import cached_property
 from pathlib import Path
 from typing import TYPE_CHECKING
 
@@ -9,7 +9,6 @@
     from poetry.core.packages.dependency import Dependency
 
 
-# TODO: Convert to dataclass once python 2.7, 3.5 is dropped
 class BuildSystem:
     def __init__(
         self, build_backend: str | None = None, requires: list[str] | None = None
@@ -20,36 +19,31 @@ def __init__(
             else "setuptools.build_meta:__legacy__"
         )
         self.requires = requires if requires is not None else ["setuptools", "wheel"]
-        self._dependencies: list[Dependency] | None = None
 
-    @property
+    @cached_property
     def dependencies(self) -> list[Dependency]:
-        if self._dependencies is None:
-            # avoid circular dependency when loading DirectoryDependency
-            from poetry.core.packages.dependency import Dependency
-            from poetry.core.packages.directory_dependency import DirectoryDependency
-            from poetry.core.packages.file_dependency import FileDependency
-
-            self._dependencies = []
-            for requirement in self.requires:
-                dependency = None
-                try:
-                    dependency = Dependency.create_from_pep_508(requirement)
-                except ValueError:
-                    # PEP 517 requires can be path if not PEP 508
-                    path = Path(requirement)
-                    # compatibility Python < 3.8
-                    # https://docs.python.org/3/library/pathlib.html#methods
-                    with suppress(OSError):
-                        if path.is_file():
-                            dependency = FileDependency(name=path.name, path=path)
-                        elif path.is_dir():
-                            dependency = DirectoryDependency(name=path.name, path=path)
-
-                if dependency is None:
-                    # skip since we could not determine requirement
-                    continue
-
-                self._dependencies.append(dependency)
-
-        return self._dependencies
+        # avoid circular dependency when loading DirectoryDependency
+        from poetry.core.packages.dependency import Dependency
+        from poetry.core.packages.directory_dependency import DirectoryDependency
+        from poetry.core.packages.file_dependency import FileDependency
+
+        dependencies = []
+        for requirement in self.requires:
+            dependency = None
+            try:
+                dependency = Dependency.create_from_pep_508(requirement)
+            except ValueError:
+                # PEP 517 requires can be path if not PEP 508
+                path = Path(requirement)
+                if path.is_file():
+                    dependency = FileDependency(name=path.name, path=path)
+                elif path.is_dir():
+                    dependency = DirectoryDependency(name=path.name, path=path)
+
+            if dependency is None:
+                # skip since we could not determine requirement
+                continue
+
+            dependencies.append(dependency)
+
+        return dependencies

src/poetry/core/pyproject/toml.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 from contextlib import suppress
+from functools import cached_property
 from typing import TYPE_CHECKING
 from typing import Any
 
@@ -16,7 +17,6 @@ class PyProjectTOML:
     def __init__(self, path: Path) -> None:
         self._path = path
         self._data: dict[str, Any] | None = None
-        self._build_system: BuildSystem | None = None
 
     @property
     def path(self) -> Path:
@@ -46,23 +46,20 @@ def data(self) -> dict[str, Any]:
 
         return self._data
 
-    @property
+    @cached_property
     def build_system(self) -> BuildSystem:
-        if self._build_system is None:
-            build_backend = None
-            requires = None
-
-            if not self.path.exists():
-                build_backend = "poetry.core.masonry.api"
-                requires = ["poetry-core"]
-
-            container = self.data.get("build-system", {})
-            self._build_system = BuildSystem(
-                build_backend=container.get("build-backend", build_backend),
-                requires=container.get("requires", requires),
-            )
-
-        return self._build_system
+        build_backend = None
+        requires = None
+
+        if not self.path.exists():
+            build_backend = "poetry.core.masonry.api"
+            requires = ["poetry-core"]
+
+        container = self.data.get("build-system", {})
+        return BuildSystem(
+            build_backend=container.get("build-backend", build_backend),
+            requires=container.get("requires", requires),
+        )
 
     @property
     def poetry_config(self) -> dict[str, Any]: