lib/utils/pyhelp: Extract implementation of help(obj) to a library function.

Several ports use identical code for the 1-argument form of the builtin
help function.  Move this code to a library function to allow easier
re-use by ports.

lib/utils/pyhelp.c

+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2013-2016 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <stdio.h>
+
+#include "lib/utils/pyhelp.h"
+
+STATIC void pyhelp_print_info_about_object(mp_obj_t name_o, mp_obj_t value) {
+    printf("  ");
+    mp_obj_print(name_o, PRINT_STR);
+    printf(" -- ");
+    mp_obj_print(value, PRINT_STR);
+    printf("\n");
+}
+
+// Helper for 1-argument form of builtin help
+//
+// Typically a port will define a help function thus:
+//
+// STATIC const char *const myport_help_text =
+// "Welcome to MicroPython!\n"
+// "\n"
+// "...information specific to this port e.g. modules available...";
+//
+// STATIC mp_obj_t myport_help(mp_uint_t n_args, const mp_obj_t *args) {
+//     if (n_args == 0) {
+//         printf("%s", myport_help_text);
+//     } else {
+//         pyhelp_print_obj(args[0]);
+//     }
+//     return mp_const_none;
+// }
+// MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_builtin_help_obj, 0, 1, myport_help);
+//
+void pyhelp_print_obj(const mp_obj_t obj) {
+    // try to print something sensible about the given object
+    printf("object ");
+    mp_obj_print(obj, PRINT_STR);
+    printf(" is of type %s\n", mp_obj_get_type_str(obj));
+
+    mp_map_t *map = NULL;
+    if (MP_OBJ_IS_TYPE(obj, &mp_type_module)) {
+        map = mp_obj_dict_get_map(mp_obj_module_get_globals(obj));
+    } else {
+        mp_obj_type_t *type;
+        if (MP_OBJ_IS_TYPE(obj, &mp_type_type)) {
+            type = obj;
+        } else {
+            type = mp_obj_get_type(obj);
+        }
+        if (type->locals_dict != MP_OBJ_NULL && MP_OBJ_IS_TYPE(type->locals_dict, &mp_type_dict)) {
+            map = mp_obj_dict_get_map(type->locals_dict);
+        }
+    }
+    if (map != NULL) {
+        for (uint i = 0; i < map->alloc; i++) {
+            if (map->table[i].key != MP_OBJ_NULL) {
+                pyhelp_print_info_about_object(map->table[i].key, map->table[i].value);
+            }
+        }
+    }
+}

lib/utils/pyhelp.h

+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2013-2016 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#ifndef __MICROPY_INCLUDED_LIB_UTILS_PYHELP_H__
+#define __MICROPY_INCLUDED_LIB_UTILS_PYHELP_H__
+
+#include "py/obj.h"
+
+void pyhelp_print_obj(const mp_obj_t obj);
+
+#endif // __MICROPY_INCLUDED_LIB_UTILS_PYHELP_H__