Set for toml dynamic version

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "git-version-utils"
-version = "0.0.0"
+dynamic = ["version"]
 description = "Extract version information from a Git repository and output as environment variables"
 readme = "README.md"
 authors = [
@@ -22,4 +22,7 @@ Repository = "https://github.com/synacker/git_version_utils"
 git-version = "git_version.cli:main"
 
 [tool.setuptools.packages.find]
-where = ["src"]
+where = ["src"]
+
+[tool.setuptools.dynamic]
+version = { attr = "git_version._version.__version__" }

setup.py

@@ -4,24 +4,47 @@
 Run `python tools/write_version.py` before building to generate
 src/git_version/_version.py with the correct version.
 
-The version in pyproject.toml is a fallback placeholder (0.0.0).
+The version in pyproject.toml is declared as dynamic and resolved
+from git_version._version.__version__ at build time.
 """
 
 import os
 import re
+from pathlib import Path
 
 from setuptools import setup
 
 
 def get_version() -> str:
-    """Get the package version from pyproject.toml."""
-    pyproject = os.path.join(os.path.dirname(__file__), "pyproject.toml")
-    if not os.path.exists(pyproject):
-        return "0.0.0"
-    with open(pyproject, "r") as f:
-        content = f.read()
-    match = re.search(r'^version\s*=\s*"([^"]+)"', content, re.MULTILINE)
-    return match.group(1) if match else "0.0.0"
+    """Get the package version from the generated _version.py or from git.
+
+    Priority:
+    1. src/git_version/_version.py (generated by tools/write_version.py)
+    2. GIT_VERSION_UTILS_VERSION environment variable
+    3. pyproject.toml fallback (0.0.0)
+    """
+    # Try _version.py first (generated by tools/write_version.py)
+    version_py = Path(__file__).parent / "src" / "git_version" / "_version.py"
+    if version_py.exists():
+        ns: dict[str, str] = {}
+        exec(version_py.read_text(), ns)
+        if "__version__" in ns:
+            return ns["__version__"]
+
+    # Try environment variable
+    env_version = os.environ.get("GIT_VERSION_UTILS_VERSION")
+    if env_version:
+        return env_version
+
+    # Fallback to pyproject.toml
+    pyproject = Path(__file__).parent / "pyproject.toml"
+    if pyproject.exists():
+        content = pyproject.read_text()
+        match = re.search(r'^version\s*=\s*"([^"]+)"', content, re.MULTILINE)
+        if match:
+            return match.group(1)
+
+    return "0.0.0"
 
 
 if __name__ == "__main__":