Add update --recreate option

soap/_cli.py

@@ -81,6 +81,10 @@ def update(
         None,
         help="Environment to update. If not specified, all environments will be updated.",
     ),
+    recreate: bool = Option(
+        False,
+        help="Delete and recreate the environment(s), rather than attempting to update in place",
+    ),
 ):
     """
     Update Conda environments.
@@ -96,7 +100,11 @@ def update(
             + f"from '{this_env.yml_path}' "
             + f"in '{this_env.env_path}':\u001b[0m"
         )
-        soap.prepare_env(this_env, ignore_cache=True)
+        soap.prepare_env(
+            this_env,
+            ignore_cache=True,
+            allow_update=not recreate,
+        )
 
 
 @app.command()

soap/_soap.py

@@ -5,7 +5,11 @@
 import filecmp
 
 
-def prepare_env(env: Env, ignore_cache=False):
+def prepare_env(
+    env: Env,
+    ignore_cache: bool = False,
+    allow_update: bool = True,
+):
     """
     Prepare the provided environment
 
@@ -18,6 +22,9 @@ def prepare_env(env: Env, ignore_cache=False):
         If True, rebuild the environment even if the cache suggests it is
         up-to-date. If False, only rebuild the environment when the YAML file
         itself has changed since the last build.
+    allow_update
+        If ``True``, attempt to update an existing environment. If ``False``,
+        delete and recreate an existing environment.
     """
     path_yml = env.yml_path
     path_env = env.env_path
@@ -29,9 +36,12 @@ def prepare_env(env: Env, ignore_cache=False):
         or (not filecmp.cmp(path_cached_yml, path_yml))
     ):
         soap.conda.env_from_file(
-            path_yml, path_env, install_current=env.install_current
+            path_yml,
+            path_env,
+            install_current=env.install_current,
+            allow_update=allow_update,
         )
-        shutil.copy2(path_yml, path_env)
+        shutil.copy2(path_yml, path_cached_yml)
 
 
 def run_in_env(args: Sequence[str], env: Env):

soap/conda.py

@@ -56,6 +56,7 @@ def env_from_file(
     file: Union[str, Path],
     env_path: Union[str, Path],
     install_current=False,
+    allow_update: bool = True,
 ):
     """
     Create or update an enviroment from a Conda environment YAML file
@@ -70,8 +71,15 @@ def env_from_file(
     install_current
         If ``True``, the root directory of the current Git repository will be
         installed in dev mode with `pip install -e`
+    allow_update
+        If ``True``, attempt to update an existing environment. If ``False``,
+        delete and recreate an existing environment.
     """
-    if Path(env_path).exists():
+    env_path = Path(env_path)
+    if not allow_update:
+        env_path.unlink(missing_ok=True)
+
+    if env_path.exists() and allow_update:
         conda(
             [
                 "env",