From 2c087c12b8d7c2ee93a0ac4714e05216facdcfea Mon Sep 17 00:00:00 2001
From: Tim Hoffmann <2836374+timhoffm@users.noreply.github.com>
Date: Thu, 13 Feb 2025 23:49:17 +0100
Subject: [PATCH] FIX: Fix unit example so that we can unpin numpy>2.1

Closes #28780.

The underlying problem is that operations on numpy scalars try to
eagerly convert the other operand to an array. As a result `scalar = np
.float64
(2); scalar * radians` would result in a numpy scalar. But we don't want
 that.
Instead we enforce `radians.__rmul__(scalar)` by giving the unit a
higher
`__array_priority__`. See also https://github
.com/numpy/numpy/issues/17650.

I haven't found any specific change notes on this in numpy 2.1.
Interestingly, the full story is even more complex. Also for numpy<2.1
`radians.__rmul__(scalar)` is not called, but there seems another
mechanism through __array__ and __array_warp__ catching back in so that
the result is again a TaggedValue. But I have not fully investigated why
 it worked previously. In fact, we want the solution here with going
 through __rmul__, and that works for all numpy versions.

`
---
 .circleci/config.yml                    | 2 +-
 environment.yml                         | 2 +-
 galleries/examples/units/basic_units.py | 5 +++++
 3 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/.circleci/config.yml b/.circleci/config.yml
index e7348b868d4b..40ba933cf0d9 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -98,7 +98,7 @@ commands:
     parameters:
       numpy_version:
         type: string
-        default: "~=2.0.0"
+        default: ""
     steps:
       - run:
           name: Install Python dependencies
diff --git a/environment.yml b/environment.yml
index 7b9ff51ae325..7593700f247a 100644
--- a/environment.yml
+++ b/environment.yml
@@ -18,7 +18,7 @@ dependencies:
   - kiwisolver>=1.3.1
   - pybind11>=2.13.2
   - meson-python>=0.13.1
-  - numpy<2.1
+  - numpy
   - pillow>=9
   - pkg-config
   - pygobject
diff --git a/galleries/examples/units/basic_units.py b/galleries/examples/units/basic_units.py
index 3f64d145b65e..486918a8eafc 100644
--- a/galleries/examples/units/basic_units.py
+++ b/galleries/examples/units/basic_units.py
@@ -193,6 +193,11 @@ def get_unit(self):
 
 
 class BasicUnit:
+    # numpy scalars convert eager and np.float64(2) * BasicUnit('cm')
+    # would thus return a numpy scalar. To avoid this, we increase the
+    # priority of the BasicUnit.
+    __array_priority__ = np.float64(0).__array_priority__ + 1
+
     def __init__(self, name, fullname=None):
         self.name = name
         if fullname is None: