From d24fce726ff77b0d00e653a651c7045f728ce4ff Mon Sep 17 00:00:00 2001
From: Giovani Hidalgo Ceotto <ghceotto@gmail.com>
Date: Sat, 12 Nov 2022 00:43:09 -0300
Subject: [PATCH 1/4] ENH: created a cached_property decorator

---
 rocketpy/tools.py | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)
 create mode 100644 rocketpy/tools.py

diff --git a/rocketpy/tools.py b/rocketpy/tools.py
new file mode 100644
index 000000000..f79a8e733
--- /dev/null
+++ b/rocketpy/tools.py
@@ -0,0 +1,21 @@
+_NOT_FOUND = object()
+
+
+class cached_property:
+    def __init__(self, func):
+        self.func = func
+        self.attrname = None
+        self.__doc__ = func.__doc__
+
+    def __set_name__(self, owner, name):
+        self.attrname = name
+
+    def __get__(self, instance, owner=None):
+        if instance is None:
+            return self
+        cache = instance.__dict__
+        val = cache.get(self.attrname, _NOT_FOUND)
+        if val is _NOT_FOUND:
+            val = self.func(instance)
+            cache[self.attrname] = val
+        return val

From d7a8e604530285d3f6d1c7c87ed949785829be22 Mon Sep 17 00:00:00 2001
From: Giovani Hidalgo Ceotto <ghceotto@gmail.com>
Date: Sat, 12 Nov 2022 00:43:48 -0300
Subject: [PATCH 2/4] FIX: import local cached_property if standard does not
 exist

---
 rocketpy/Flight.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/rocketpy/Flight.py b/rocketpy/Flight.py
index 8be8a2342..cb908dcab 100644
--- a/rocketpy/Flight.py
+++ b/rocketpy/Flight.py
@@ -9,7 +9,6 @@
 import math
 import time
 import warnings
-from functools import cached_property
 
 import matplotlib.pyplot as plt
 import numpy as np
@@ -18,6 +17,11 @@
 
 from .Function import Function
 
+try:
+    from functools import cached_property
+except ImportError:
+    from .tools import cached_property
+
 
 class Flight:
     """Keeps all flight information and has a method to simulate flight.

From b81e30f8d9c22b7f66ea5c544b6f27364525ffbe Mon Sep 17 00:00:00 2001
From: Giovani Hidalgo Ceotto <ghceotto@gmail.com>
Date: Sat, 12 Nov 2022 23:09:03 -0300
Subject: [PATCH 3/4] ENH: Prevents cached_property decorator from being used
 before `__set_name__`

---
 rocketpy/tools.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/rocketpy/tools.py b/rocketpy/tools.py
index f79a8e733..a283a498b 100644
--- a/rocketpy/tools.py
+++ b/rocketpy/tools.py
@@ -13,6 +13,9 @@ def __set_name__(self, owner, name):
     def __get__(self, instance, owner=None):
         if instance is None:
             return self
+        if self.attrname is None:
+            raise TypeError(
+                "Cannot use cached_property instance without calling __set_name__ on it.")
         cache = instance.__dict__
         val = cache.get(self.attrname, _NOT_FOUND)
         if val is _NOT_FOUND:

From a46aa2efca8294357ec16e7274e466062c08eab2 Mon Sep 17 00:00:00 2001
From: Lint Action <lint-action@samuelmeuli.com>
Date: Sun, 13 Nov 2022 02:09:36 +0000
Subject: [PATCH 4/4] Fix code style issues with Black

---
 rocketpy/tools.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/rocketpy/tools.py b/rocketpy/tools.py
index a283a498b..9b5d1b59c 100644
--- a/rocketpy/tools.py
+++ b/rocketpy/tools.py
@@ -15,7 +15,8 @@ def __get__(self, instance, owner=None):
             return self
         if self.attrname is None:
             raise TypeError(
-                "Cannot use cached_property instance without calling __set_name__ on it.")
+                "Cannot use cached_property instance without calling __set_name__ on it."
+            )
         cache = instance.__dict__
         val = cache.get(self.attrname, _NOT_FOUND)
         if val is _NOT_FOUND: