Confirm support for Python 3.13 and drop 3.8

.github/workflows/pytest.yaml

@@ -24,11 +24,11 @@ jobs:
         - ubuntu-latest
         - windows-latest
         python-version:
-        - "3.8"  # Earliest version supported by ixmp
-        - "3.9"
+        - "3.9"  # Earliest version supported by ixmp
         - "3.10"
         - "3.11"
-        - "3.12"  # Latest supported by ixmp
+        - "3.12"
+        - "3.13"  # Latest supported by ixmp
         gams-version:
         # Version used until 2024-07; disabled
         # - 25.1.1
@@ -43,17 +43,13 @@ jobs:
 
         exclude:
         # Specific version combinations that are invalid / not to be used
-        # No arm64 distribution for this version of GAMS
-        # - { os: macos-latest, gams-version: 25.1.1}
         # No arm64 distributions of JPype for these Pythons
-        - { os: macos-latest, python-version: "3.8" }
         - { os: macos-latest, python-version: "3.9" }
         # Redundant with macos-latest
         - { os: macos-13, python-version: "3.10" }
         - { os: macos-13, python-version: "3.11" }
         - { os: macos-13, python-version: "3.12" }
-        # Example: pandas 2.0 requires Python >= 3.8
-        # - { python-version: "3.7", pandas-version: "==2.0.0rc0" }
+        - { os: macos-13, python-version: "3.13" }
 
       fail-fast: false
 
@@ -80,6 +76,8 @@ jobs:
 
     - uses: r-lib/actions/setup-r@v2
       id: setup-r
+      with:
+        r-version: "4.4.1"
 
     - name: Cache GAMS installer and R packages
       uses: actions/cache@v4
@@ -109,12 +107,9 @@ jobs:
         # commented: use with "pandas-version" in the matrix, above
         # pip install --upgrade pandas${{ matrix.pandas-version }}
 
-        # TEMPORARY Work around hgrecco/pint#2007;
-        # see https://github.com/iiasa/ixmp/issues/534
-        pip install "pint != 0.24.0" "numpy < 2"
-
-        # TEMPORARY Work around pretenders/pretenders#153
-        pip install "bottle < 0.13"
+        # TEMPORARY With Python 3.13 pyam-iamc resolves to 1.3.1, which in turn
+        # limits pint < 0.17. Override. cf. iiasa/ixmp#544
+        pip install --upgrade pint
 
     - name: Install R dependencies and tutorial requirements
       run: |

.gitignore

@@ -60,6 +60,7 @@ prof/
 
 # Editors and IDEs
 .editorconfig
+.vscode
 *.iml
 /**/.idea
 

.pre-commit-config.yaml

@@ -17,6 +17,7 @@ repos:
     - pandas-stubs
     - pytest
     - sphinx
+    - werkzeug
     - xarray
     args: ["."]
 - repo: https://github.com/astral-sh/ruff-pre-commit

RELEASE_NOTES.rst

@@ -1,6 +1,8 @@
 Next release
 ============
 
+- :mod:`ixmp` is tested and compatible with `Python 3.13 <https://www.python.org/downloads/release/python-3130/>`__ (:pull:`544`).
+- Support for Python 3.8 is dropped (:pull:`544`), as it has reached end-of-life.
 - :mod:`ixmp` locates GAMS API libraries needed for the Java code underlying :class:`.JDBCBackend` based on the system GAMS installation (:pull:`532`).
   As a result:
 

doc/install.rst

@@ -34,7 +34,7 @@ Install system dependencies
 Python
 ------
 
-Python version 3.8 or later is required.
+Python version 3.9 or later is required.
 
 GAMS (required)
 ---------------
@@ -89,7 +89,7 @@ After installing GAMS, we recommend that new users install Anaconda, and then us
 Advanced users may choose to install :mod:`ixmp` from source code (next section).
 
 4. Install Python via either `Miniconda`_ or `Anaconda`_. [1]_
-   We recommend the latest version; currently Python 3.10. [2]_
+   We recommend the latest version; currently Python 3.13. [2]_
 
 5. Open a command prompt.
    We recommend Windows users use the “Anaconda Prompt” to avoid issues with permissions and environment variables when installing and using :mod:`ixmp`.

ixmp/_config.py

@@ -4,7 +4,7 @@
 from copy import copy
 from dataclasses import asdict, dataclass, field, fields, make_dataclass
 from pathlib import Path
-from typing import Any, Dict, Optional, Tuple, Type
+from typing import Any, Optional
 
 log = logging.getLogger(__name__)
 
@@ -121,7 +121,7 @@ def delete_field(self, name):
         data.pop(name)
         return new_cls, new_cls(**data)
 
-    def keys(self) -> Tuple[str, ...]:
+    def keys(self) -> tuple[str, ...]:
         return tuple(map(lambda f: f.name.replace("_", " "), fields(self)))
 
     def set(self, name: str, value: Any, strict: bool = True):
@@ -214,7 +214,7 @@ class Config:
     #: ``ixmp.config.values["platform"]["platform name"]…``.
     values: BaseValues
 
-    _ValuesClass: Type
+    _ValuesClass: type[BaseValues]
 
     def __init__(self, read: bool = True):
         self._ValuesClass = BaseValues
@@ -261,7 +261,7 @@ def get(self, name: str) -> Any:
         """Return the value of a configuration key `name`."""
         return self.values[name]
 
-    def keys(self) -> Tuple[str, ...]:
+    def keys(self) -> tuple[str, ...]:
         """Return the names of all registered configuration keys."""
         return self.values.keys()
 
@@ -383,7 +383,7 @@ def add_platform(self, name: str, *args, **kwargs):
 
         self.values["platform"][name] = info
 
-    def get_platform_info(self, name: str) -> Tuple[str, Dict[str, Any]]:
+    def get_platform_info(self, name: str) -> tuple[str, dict[str, Any]]:
         """Return information on configured Platform `name`.
 
         Parameters

ixmp/backend/__init__.py

@@ -1,7 +1,10 @@
 """Backend API."""
 
 from enum import IntFlag
-from typing import Dict, List, Type, Union
+from typing import TYPE_CHECKING, Union
+
+if TYPE_CHECKING:
+    import ixmp.backend.base
 
 #: Lists of field names for tuples returned by Backend API methods.
 #:
@@ -46,12 +49,12 @@
 #: Partial list of dimensions for the IAMC data structure, or “IAMC format”. This omits
 #: "year" and "subannual" which appear in some variants of the structure, but not in
 #: others.
-IAMC_IDX: List[Union[str, int]] = ["model", "scenario", "region", "variable", "unit"]
+IAMC_IDX: list[Union[str, int]] = ["model", "scenario", "region", "variable", "unit"]
 
 
 #: Mapping from names to available backends. To register additional backends, add
 #: entries to this dictionary.
-BACKENDS: Dict[str, Type] = {}
+BACKENDS: dict[str, type["ixmp.backend.base.Backend"]] = {}
 
 
 class ItemType(IntFlag):