diff options
| -rw-r--r-- | io.c | 8 |
1 files changed, 6 insertions, 2 deletions
@@ -6318,8 +6318,12 @@ rb_io_stdio_file(rb_io_t *fptr) * <code>intern</code> is the internal encoding. * <code>fmode</code> must be combination of the directives. See * the description of class +IO+ for a description of the directives. - * Changing reading/writing mode from the original io object is not - * supported on some platforms, e.g. Windows. + * + * When the mode of original IO is read only, the mode cannot be changed to + * be writable. Similarly, the mode cannot be changed from write only to + * readable. + * If such a wrong change is directed, timing where the error actually occurs + * is different according to the platform. * * ==== Options * <code>opt</code> can have the following keys |