include/ruby/internal/core/rfile.h: add doxygen

Must not be a bad idea to improve documents. [ci skip]

1 files changed, 15 insertions, 0 deletions

diff --git a/include/ruby/internal/core/rfile.h b/include/ruby/internal/core/rfile.h
index 71699a0b7e..f8dddde9e5 100644
--- a/include/ruby/internal/core/rfile.h
+++ b/include/ruby/internal/core/rfile.h
@@ -27,10 +27,25 @@
  * into ruby/ruby.h.  We follow that tradition. */
 struct rb_io_t;
 
+/**
+ * Ruby's File  and IO.  Ruby's  IO are not  just file descriptors.   They have
+ * buffers.   They also  have  encodings.  Various  information are  controlled
+ * using this struct.
+ */
 struct RFile {
+
+    /** Basic part, including flags and class. */
     struct RBasic basic;
+
+    /** IO's specific fields. */
     struct rb_io_t *fptr;
 };
 
+/**
+ * Convenient casting macro.
+ *
+ * @param   obj  An object, which is in fact an ::RFile.
+ * @return  The passed object casted to ::RFile.
+ */
 #define RFILE(obj) RBIMPL_CAST((struct RFile *)(obj))
 #endif /* RBIMPL_RFILE_H */