Lazy import implementation for surfarray, sndarray

Author: aatle

docs/reST/ref/sndarray.rst

@@ -23,6 +23,8 @@ Each sample is an 8-bit or 16-bit integer, depending on the data format. A
 stereo sound file has two values per sample, while a mono sound file only has
 one.
 
+.. versionchanged:: 2.5.3 sndarray module is lazily loaded to avoid loading NumPy needlessly
+
 .. function:: array
 
    | :sl:`copy Sound samples into an array`

docs/reST/ref/surfarray.rst

@@ -35,6 +35,8 @@ pixels from the surface and any changes performed to the array will make changes
 in the surface. As this last functions share memory with the surface, this one
 will be locked during the lifetime of the array.
 
+.. versionchanged:: 2.5.3 surfarray module is lazily loaded to avoid loading NumPy needlessly
+
 .. function:: array2d
 
    | :sl:`Copy pixels into a 2d array`

src_py/__init__.py

@@ -300,16 +300,36 @@ def PixelArray(surface):  # pylint: disable=unused-argument
 except (ImportError, OSError):
     scrap = MissingModule("scrap", urgent=0)
 
-try:
-    import pygame.surfarray
-except (ImportError, OSError):
-    surfarray = MissingModule("surfarray", urgent=0)
+# Two lazily imported modules to avoid loading numpy unnecessarily
 
-try:
-    import pygame.sndarray
-except (ImportError, OSError):
+from importlib.util import LazyLoader, find_spec, module_from_spec
+
+
+def lazy_import(name):
+    """See https://docs.python.org/3/library/importlib.html#implementing-lazy-imports
+
+    Only load modules upon their first attribute access.
+    Lazily imported modules are directly referenced in packager_imports function.
+    """
+    spec = find_spec("pygame." + name)
+    loader = LazyLoader(spec.loader)
+    spec.loader = loader
+    module = module_from_spec(spec)
+    sys.modules[spec.name] = module
+    loader.exec_module(module)
+    return module
+
+
+if find_spec("numpy") is not None:
+    surfarray = lazy_import("surfarray")
+    sndarray = lazy_import("sndarray")
+else:
+    # Preserve MissingModule behavior when numpy is not installed
+    surfarray = MissingModule("surfarray", urgent=0)
     sndarray = MissingModule("sndarray", urgent=0)
 
+del LazyLoader, find_spec, lazy_import, module_from_spec
+
 try:
     import pygame._debug
     from pygame._debug import print_debug_info
@@ -366,6 +386,10 @@ def packager_imports():
     import pygame.macosx
     import pygame.colordict
 
+    # lazy imports
+    import pygame.surfarray
+    import pygame.sndarray
+
 
 # make Rects pickleable