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Re: [PATCH 19/22] Class-ify ui_out_impl


On 2016-11-30 08:09, Pedro Alves wrote:
+ui_file *
+cli_out_set_stream (struct ui_out *uiout, ui_file *stream)
+{
+ cli_ui_out_impl *impl = dynamic_cast<cli_ui_out_impl *> (ui_out_impl (uiout));

"dynamic_cast" is a code smell.  In this case, I think it
stems from the fact that we have separate ui_out and ui_out_impl
hierarchies.  If we had a simple hierarchy, then this function would
take a  cli_ui_out pointer as argument, or even be a
method of cli_ui_out.

Indeed it's not great. This patchset is mostly about keeping the structure we have, but express it as C++. So I'd argue that it uncovers something that already existed. I think it makes the situation a tiny bit better though, as we have some type checking with dynamic_cast. With the static cast we have currently, if you happened to pass the wrong kind of object, it would probably fail catastrophically.

I'll consider working on merging ui_out and ui_out_impl_* in a single class hierarchy. My first question is: what is a good pattern for the overlapping methods. For example, table_begin. We'll want to execute the version of the base class, which will then call the specialization. So we can't use the same name for both. So, keep table_begin for the base class, and table_begin_impl for the derived classes?

+class cli_ui_out_impl : public ui_out_impl_base
+{
+public:

-struct cli_ui_out_data
-  {
-    std::vector<ui_file *> streams;
-    int suppress_output;
-  };
+  cli_ui_out_impl (ui_file *stream);

explicit.

Done.

+private:
+  void field_separator (void);

"(void)".  Probably easier to grep the whole patch set to
find such cases and handle all of them.

Yep, that's what I did the first time I saw that comment.

+mi_ui_out_impl::table_begin (int nr_cols, int nr_rows,
+			     const char *tblid)
 {
-  mi_open (uiout, tblid, ui_out_type_tuple);
-  mi_field_int (uiout, -1, -1, ui_left, "nr_rows", nr_rows);
-  mi_field_int (uiout, -1, -1, ui_left, "nr_cols", nr_cols);
-  mi_open (uiout, "hdr", ui_out_type_list);
+  open (tblid, ui_out_type_tuple);

FYI, it's due to names like "open" potentially conflicting
with gnulib replacing global namespace C functions with
#define open rpl_open
that I'm looking at switching to use gnulib's C++ namespace
support.  Luckily, looks like gnulib doesn't replace
"open" currently, so you don't need to wait for that:

 $ grep -rn open | grep rpl_
 stdio.in.h:191:#   define fdopen rpl_fdopen
 stdio.in.h:264:#   define fopen rpl_fopen
 stdio.in.h:388:#   define freopen rpl_freopen
 stdio.in.h:820:#   define popen rpl_popen
 dirent.in.h:79:#   define opendir rpl_opendir
 dirent.in.h:198:#   define fdopendir rpl_fdopendir

 void
-mi_table_end (struct ui_out *uiout)
+mi_ui_out_impl::table_end ()
 {
-  mi_out_data *data = (mi_out_data *) ui_out_data (uiout);
-
-  data->suppress_output = 0;
-  mi_close (uiout, ui_out_type_list); /* body */
-  mi_close (uiout, ui_out_type_tuple);
+  m_suppress_output = 0;
+  close (ui_out_type_list); /* body */
+  close (ui_out_type_tuple);

However:

 $ grep -rn close | grep rpl_
 stdio.in.h:172:#   define fclose rpl_fclose
 dirent.in.h:131:#   define closedir rpl_closedir
 unistd.in.h:303:#   define close rpl_close


:-/

I'd like to post the gnulib namespace patch this week,
but I'm not sure I'll be able to.

And I guess it happens to work anyway for me because both the declaration, definition and usages get replaced?

Should I wait for your patch to get in (I'm not particularly in a hurry), or we can get it in despite "close" getting replaced?

+  virtual void field_string (int fldno, int width, ui_align align,
+			     const char *fldname, const char *string) override;
+  virtual void ATTRIBUTE_PRINTF(6,0)
+ field_fmt (int fldno, int width, ui_align align, const char *fldname,
+	       const char *format, va_list args) override;

It's more usual to put the ATTRIBUTE_PRINTFs at the end of the
declaration.  Also, missing space before parens.  Something like:

  virtual void field_fmt (int fldno, int width, ui_align align,
                          const char *fldname,
                          const char *format, va_list args) override
    ATTRIBUTE_PRINTF (6,0);

?

Ah, I put them there because I though it was the only place where it worked when applied to virtual pure functions. But apparently, this works:

 98   virtual void field_fmt (int fldno, int width, ui_align align,
99 const char *fldname, const char *format, va_list args)
100     ATTRIBUTE_PRINTF(6,0) = 0;

I thought I had tried it and it didn't work, but I was wrong. I'll fix them so they look like that.

+  virtual void spaces (int numspaces) override;
+  virtual void text (const char *string) override;
+ virtual void ATTRIBUTE_PRINTF(2,0) message (const char *format, va_list args)
+    override;

Ditto. There are other instances in the patch. I won't point them all.

I'll go over all the patches and fix that.

+private:
+
+  void field_separator ();
+  void open (const char *name, ui_out_type type);
+  void close (ui_out_type type);
+
+  int m_suppress_field_separator;
+  int m_suppress_output;

bool ?

Right. I changed it, but from what I can see MI's m_suppress_output is never used (as in never set to true). If that's indeed the case, I'll make a separate patch to remove it in the current master code.

CLI has a m_suppress_output that is used though, I changed it as well to bool.

+  int m_mi_version;
+  std::vector<ui_file *> m_streams;
+};



-typedef struct tui_ui_out_data tui_out_data;
+class tui_ui_out_impl : public cli_ui_out_impl
+{
+public:
+
+  tui_ui_out_impl (ui_file *stream);

explicit.

Done.

+
+ void field_int (int fldno, int width, ui_align align, const char *fldname,
+		  int value) override;
+ void field_string (int fldno, int width, ui_align align, const char *fldname,
+		     const char *string) override;
+  void ATTRIBUTE_PRINTF(6,0)
+ field_fmt (int fldno, int width, ui_align align, const char *fldname,
+	       const char *format, va_list args) override;

attribute placement, space before parens.

Done.

+  void text (const char *string) override;



+  virtual int redirect (struct ui_file * outstream) = 0;
+
+ /* Set as not MI-like by default. It is overridden in subclasses if
+     necessary.  */
+
+  virtual int is_mi_like_p ()
+  { return 0; }

bool ?

Done.

Thanks for the review. I'll try to push the small patches that were OK'ed without comments, and re-post a complete v2 series.


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