Packaging for PyPI (#18)

### Overview

Add necessary files and structure to create the package for the Python
Package Index (PyPI).

- [x] Add LICENSE file, copied from
https://github.com/BLAST-ImpactX/impactx/blob/development/LICENSE.txt
- [x] Add `pyproject.toml`

Close #17.

### To do
- [x] Test build: build with `python3 -m build` locally
- [x] Test upload: upload to TestPyPI
- [x] Test installation: install and import locally

See
#18 (comment)
for a quick overview of how I tested this.

---------

Co-authored-by: Axel Huebl <[email protected]>

Author: EZoni

LICENSE

@@ -0,0 +1,42 @@
+PALS Python Copyright (c) 2025, The Regents of the University of California,
+through Lawrence Berkeley National Laboratory (subject to receipt of
+any required approvals from the U.S. Dept. of Energy). All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+(1) Redistributions of source code must retain the above copyright notice,
+this list of conditions and the following disclaimer.
+
+(2) Redistributions in binary form must reproduce the above copyright
+notice, this list of conditions and the following disclaimer in the
+documentation and/or other materials provided with the distribution.
+
+(3) Neither the name of the University of California, Lawrence Berkeley
+National Laboratory, U.S. Dept. of Energy nor the names of its contributors
+may be used to endorse or promote products derived from this software
+without specific prior written permission.
+
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.
+
+You are under no obligation whatsoever to provide any bug fixes, patches,
+or upgrades to the features, functionality or performance of the source
+code ("Enhancements") to anyone; however, if you choose to make your
+Enhancements available either publicly, or directly to Lawrence Berkeley
+National Laboratory, without imposing a separate written license agreement
+for such Enhancements, then you hereby grant the following license: a
+non-exclusive, royalty-free perpetual license to install, use, modify,
+prepare derivative works, incorporate into other computer software,
+distribute, and sublicense such enhancements or derivative works thereof,
+in binary and source code form.

examples/fodo.py

@@ -4,14 +4,12 @@
 import yaml
 
 # Add the parent directory to sys.path
-sys.path.append(os.path.abspath(os.path.join(os.path.dirname(__file__), "..")))
+sys.path.append(os.path.abspath(os.path.join(os.path.dirname(__file__), "../src/")))
 
-from schema.MagneticMultipoleParameters import MagneticMultipoleParameters
-
-from schema.DriftElement import DriftElement
-from schema.QuadrupoleElement import QuadrupoleElement
-
-from schema.Line import Line
+from pals_schema.MagneticMultipoleParameters import MagneticMultipoleParameters
+from pals_schema.DriftElement import DriftElement
+from pals_schema.QuadrupoleElement import QuadrupoleElement
+from pals_schema.Line import Line
 
 
 def main():

pyproject.toml

@@ -0,0 +1,49 @@
+[build-system]
+requires = ["setuptools >= 77", "wheel"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "pals_schema"
+version = "25.08"
+dependencies = [
+  "pydantic",
+  "pyyaml",
+  "toml",
+]
+requires-python = ">=3.9"
+authors = [
+  { name="Axel Huebl", email="[email protected]" },
+  { name="Edoardo Zoni", email="[email protected]" },
+]
+maintainers = [
+  { name="Axel Huebl", email="[email protected]" },
+  { name="Edoardo Zoni", email="[email protected]" },
+]
+description = "Python implementation for the Particle Accelerator Lattice Standard (PALS)"
+readme = "README.md"
+license = "BSD-3-Clause-LBNL"
+license-files = ["LICEN[CS]E*"]
+classifiers = [
+  "Development Status :: 5 - Production/Stable",
+  "Framework :: Pydantic :: 2",
+  "Intended Audience :: Developers",
+  "Intended Audience :: Science/Research",
+  "Natural Language :: English",
+  "Programming Language :: Python :: 3",
+  "Programming Language :: Python :: 3.9",
+  "Programming Language :: Python :: 3.10",
+  "Programming Language :: Python :: 3.11",
+  "Programming Language :: Python :: 3.12",
+  "Programming Language :: Python :: 3.13",
+  "Operating System :: OS Independent",
+  "Topic :: Scientific/Engineering",
+  "Topic :: Software Development",
+]
+
+[project.optional-dependencies]
+test = ["pytest"]
+
+[project.urls]
+Documentation = "https://pals-project.readthedocs.io"
+Repository = "https://github.com/campa-consortium/pals-python"
+Issues = "https://github.com/campa-consortium/pals-python/issues"

schema/BaseElement.py renamed to src/pals_schema/BaseElement.py

@@ -1,10 +1,10 @@
 from pydantic import BaseModel, ConfigDict, Field, field_validator
 from typing import Annotated, List, Literal, Union
 
-from schema.BaseElement import BaseElement
-from schema.ThickElement import ThickElement
-from schema.DriftElement import DriftElement
-from schema.QuadrupoleElement import QuadrupoleElement
+from pals_schema.BaseElement import BaseElement
+from pals_schema.ThickElement import ThickElement
+from pals_schema.DriftElement import DriftElement
+from pals_schema.QuadrupoleElement import QuadrupoleElement
 
 
 class Line(BaseModel):