From 1490d22438759c33133bc6182e4b69ec67212958 Mon Sep 17 00:00:00 2001
From: Kodi Arfer <git@arfer.net>
Date: Tue, 23 Apr 2024 10:12:44 -0400
Subject: [PATCH] Add `import-path`

---
 NEWS.rst           |  1 +
 docs/index.rst     |  1 +
 hyrule/misc.hy     | 28 ++++++++++++++++++++++++++++
 tests/test_misc.hy | 21 ++++++++++++++++++++-
 4 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/NEWS.rst b/NEWS.rst
index 550aad5c..8564bbc2 100644
--- a/NEWS.rst
+++ b/NEWS.rst
@@ -16,6 +16,7 @@ New Features
 * New macro `some->`.
 * New function `sign`.
 * New function `thru`.
+* New function `import-path`.
 
 Removals
 ------------------------------
diff --git a/docs/index.rst b/docs/index.rst
index e32e3785..6dfe0365 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -137,6 +137,7 @@ API
 .. hy:autofunction:: constantly
 .. hy:autofunction:: dec
 .. hy:autofunction:: inc
+.. hy:autofunction:: import-path
 .. hy:automacro:: of
 .. hy:autofunction:: parse-args
 .. hy:automacro:: profile/calls
diff --git a/hyrule/misc.hy b/hyrule/misc.hy
index a328f9a3..3aa7e338 100644
--- a/hyrule/misc.hy
+++ b/hyrule/misc.hy
@@ -2,6 +2,8 @@
   hyrule.macrotools [defmacro!])
 
 (import
+  sys
+  importlib.util
   hy.scoping [ScopeLet]
   hyrule.collections [by2s])
 
@@ -52,6 +54,32 @@
   (+ n 1))
 
 
+(defn import-path [path [name None]]
+
+  #[[Import the Python or Hy source code at ``path`` as a module with
+  :func:`importlib.util.spec_from_file_location`, per Python's documentation.
+  Return the new module object. ``name`` defaults to ``(str (hy.gensym
+  "import-file"))``. ::
+
+    (setv p (hy.I.pathlib.Path "mymodule.hy"))
+    (.write-text p "(setv foo 3)")
+    (setv m (import-path p))
+    (print m.foo)  ; => 3]]
+
+  (when (is name None)
+    (setv name (str (hy.gensym "import-file"))))
+  (when (in name sys.modules)
+    (raise (ValueError f"The name {(hy.repr name)} is already in use in `sys.modules`.")))
+
+  ; Translated from https://github.com/python/cpython/blob/408e127159e54d87bb3464fd8bd60219dc527fac/Doc/library/importlib.rst?plain=1#L1584
+  (setv spec (importlib.util.spec-from-file-location name path))
+  (setv m (importlib.util.module-from-spec spec))
+  (setv (get sys.modules name) m)
+  (.loader.exec-module spec m)
+
+  m)
+
+
 (defmacro of [base #* args]
 
   "Shorthand for type annotations with indexing. If only one argument
diff --git a/tests/test_misc.hy b/tests/test_misc.hy
index 7ffee5d4..b3f4d228 100644
--- a/tests/test_misc.hy
+++ b/tests/test_misc.hy
@@ -1,9 +1,10 @@
 (require
   hyrule [comment of smacrolet])
 (import
+  sys
   pytest
   typing [List Dict]
-  hyrule [constantly dec inc parse-args sign xor])
+  hyrule [constantly dec inc import-path parse-args sign xor])
 
 
 (defn test-constantly []
@@ -34,6 +35,24 @@
   (assert (= (inc (X)) "__add__ got 1")))
 
 
+(defn test-import-path [tmp-path]
+  (setv mp (/ tmp-path "a.hy"))
+  (.write-text mp "(setv foo 7)")
+
+  (setv m (import-path mp "mymod"))
+  (assert (= m.foo 7))
+  (assert (= m.__name__ "mymod"))
+  (assert (is (get sys.modules "mymod") m))
+
+  (setv m2 (import-path mp))
+  (assert (= m2.foo 7))
+  (assert (is-not m2 m))
+  (assert (in m2 (.values sys.modules)))
+
+  (.write-text (/ tmp-path "b.py") "bar = 3")
+  (assert (= (. (import-path (/ tmp-path "b.py")) bar) 3)))
+
+
 (defn test-of []
   (assert (= (of str) str))
   (assert (= (of List int) (get List int)))