py/builtinimport: Allow overriding of mp_builtin___import__.

This allows ports to override mp_builtin___import__.

This can be useful in MicroPython applications where
MICROPY_ENABLE_EXTERNAL_IMPORT has to be disabled due to its impact on
build size (2% to 2.5% of the minimal port). By overriding the otherwise
very minimal mp_builtin___import__, ports can still allow limited forms
of application-specific imports.

Signed-off-by: Laurens Valk <laurens@pybricks.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/py/builtin.h b/py/builtin.h
index fb1162784..7232142b7 100644
--- a/py/builtin.h
+++ b/py/builtin.h
@@ -64,7 +64,13 @@ MP_DECLARE_CONST_FUN_OBJ_KW(mp_builtin_open_obj);
 
 #endif
 
+// A port can provide its own import handler by defining mp_builtin___import__.
+#ifndef mp_builtin___import__
+#define mp_builtin___import__ mp_builtin___import___default
+#endif
 mp_obj_t mp_builtin___import__(size_t n_args, const mp_obj_t *args);
+mp_obj_t mp_builtin___import___default(size_t n_args, const mp_obj_t *args);
+
 mp_obj_t mp_micropython_mem_info(size_t n_args, const mp_obj_t *args);
 
 MP_DECLARE_CONST_FUN_OBJ_VAR(mp_builtin___build_class___obj);