Use JSON

Author: doctorperceptron

dependencies/README.md

@@ -7,7 +7,7 @@ This directory houses the files that specify and constrain the dependencies requ
 *   [Overview](#overview)
 *   [Dependency Files](#dependency-files)
     *   [`constraints-dev.txt`](#constraints-devtxt)
-    *   [`constraints-plc-dev.txt`](#constraints-plc-devtxt)
+    *   [`constraints-plc-dev.json`](#constraints-plc-devjson)
     *   [`constraints-stable.txt`](#constraints-stabletxt)
     *   [`requirements-build.txt`](#requirements-buildtxt)
     *   [`requirements-core.in`](#requirements-corein)
@@ -31,12 +31,13 @@ This file specifies the allowed versions of dependencies for building and runnin
 *   **Location:** `./constraints-dev.txt`
 *   **Purpose:** Defines dependencies for the `qml build --dev` command.
 
-### `constraints-plc-dev.txt`
+### `constraints-plc-dev.json`
 
-This file specifies the allowed versions of PennyLane, Lightning, and Catalyst for **development builds**. These files are currently installed **onyl if the demo is set to be executed** (`qml build --execute --dev`). These versions are pulled from test-pypi so that the release candidate versions are used during feature freeze. Unless you're a release manager, you likely don't need to modify this file. 
+This file specifies the allowed release versions of PennyLane, Lightning, and Catalyst for **development builds**. These packages are currently installed **only if the demo is set to be executed** (`qml build --execute --dev`). The latest version available on test-pypi, whose release version matches the constraint, is what gets installed (e.g. 0.45.0.dev15 == 0.45.0, 0.45.0rc7 == 0.45.0, 0.46.0.dev3 != 0.45.0, etc.). Only update this constraint after a new release, so that the release candidate versions continue to be used during feature freeze. Unless you're a release manager, you likely don't need to modify this file.
 
-*   **Location:** `./constraints-plc-dev.txt`
+*   **Location:** `./constraints-plc-dev.json`
 *   **Purpose:** Defines PennyLane, Lightning, and Catalyst versions for the `qml build --execute --dev` command.
+*   **Format:** JSON array of objects with the package names as keys. Order of entries must be preserved (Catalyst, then Lightning, then PennyLane).
 
 ### `constraints-stable.txt`
 

dependencies/constraints-plc-dev.json

@@ -0,0 +1,5 @@
+[
+  {"name": "pennylane-catalyst", "version": "0.15.0"},
+  {"name": "pennylane-lightning", "version": "0.45.0"},
+  {"name": "pennylane", "version": "0.45.0"}
+]

dependencies/constraints-plc-dev.txt

@@ -51,7 +51,7 @@ def dev_constraints_file(self) -> Path:
 
     @property
     def plc_dev_constraints_file(self) -> Path:
-        return self.repo_root / "dependencies" / "constraints-plc-dev.txt"
+        return self.repo_root / "dependencies" / "constraints-plc-dev.json"
 
     @property
     def build_requirements_file(self) -> Path:

lib/qml/context.py

@@ -1,6 +1,7 @@
 from dataclasses import dataclass
 from pathlib import Path, PurePosixPath
 from collections.abc import Sequence, Iterator
+from packaging.version import Version
 import shutil
 from qml.lib import fs, cmds
 from qml.lib.virtual_env import Virtualenv
@@ -297,57 +298,28 @@ def _build_demo(
         # If dev, we need to re-install the latest Catalyst, then Lightning, then PennyLane
         # in that order, regardless of conflicts/warnings. 
         if dev:
-            with open(ctx.plc_dev_constraints_file, "r") as f:
-                packages = f.readlines()
-                for package in packages:
-                    package = package.strip()
-                    if package and not package.startswith("#"):
-                        logger.info("Getting versions for %s", package)
-                        try:
-                            package_name, constraint = package.split("<", maxsplit=1)
-                        except:
-                            logger.error("Malformed constraints file for PLC dev.")
-                            raise
-                        package_versions = cmds.pip_get_versions(build_venv.python, package_name, index_url="https://test.pypi.org/simple/")
-                        for version in package_versions:
-                            if version < constraint:
-                                logger.info("Installing %s==%s", package_name, version)
-                                #Testing. Refactor this later if successful
-                                if package_name == "pennylane-catalyst":
-                                    cmds.pip_install(
-                                        build_venv.python,
-                                        "--no-cache-dir",
-                                        "--extra-index-url",
-                                        "https://test.pypi.org/simple/",
-                                        f"{package_name}=={version}",
-                                        use_uv=False,
-                                        quiet=False,
-                                    )
-                                elif package_name == "pennylane-lightning":
-                                    cmds.pip_install(
-                                        build_venv.python,
-                                        "--no-cache-dir",
-                                        "--force-reinstall",
-                                        "--no-deps",
-                                        "--extra-index-url",
-                                        "https://test.pypi.org/simple/",
-                                        f"{package_name}=={version}",
-                                        use_uv=False,
-                                        quiet=False,
-                                    )
-                                elif package_name == "pennylane":
-                                    cmds.pip_install(
-                                        build_venv.python,
-                                        "--no-cache-dir",
-                                        "--force-reinstall",
-                                        "--no-deps",
-                                        "--extra-index-url",
-                                        "https://test.pypi.org/simple/",
-                                        f"{package_name}=={version}",
-                                        use_uv=False,
-                                        quiet=False,
-                                    )
-                                break
+            base_install_args = [
+                build_venv.python,
+                "--no-cache-dir",
+                "--extra-index-url",
+                "https://test.pypi.org/simple/",
+            ]
+            with open(ctx.plc_dev_constraints_file) as f:
+                constraints = json.load(f)
+            for package in constraints:
+                logger.info("Getting versions for %s", package["name"])
+                package_versions = cmds.pip_get_versions(build_venv.python, package["name"], index_url="https://test.pypi.org/simple/")
+                # These are ruturned newest to oldest, so we can break when we find the first match
+                for version in package_versions:
+                    if Version(version).release == Version(package["version"]).release:
+                        logger.info("Installing %s==%s", package["name"], version)
+                        install_args = base_install_args.copy()
+                        if package["name"] != "pennylane-catalyst":
+                            install_args.append("--force-reinstall")
+                            install_args.append("--no-deps")
+                        install_args.append(f"{package['name']}=={version}")
+                        cmds.pip_install(*install_args, use_uv=False, quiet=False)
+                        break
             # Need to reinstall the demo's requirements file to ensure the correct versions are installed
             if demo.requirements_file:
                 cmds.pip_install(