Re: ui_out format strings for fields and styles (Re: [PATCH] Style "pwd" output)

[Pedro Alves <palves at redhat dot com>]

On 6/5/19 9:47 PM, Tom Tromey wrote:
>>>>>> "Pedro" == Pedro Alves <palves@redhat.com> writes:
> 
> Pedro> Also, since gcc expects a pointer for %p, and we want to pass an
> Pedro> enum for the style, I added a small pointer-wrapper hack -- see the
> Pedro> ptr function.  Yay C++.
> 
> We could just remove the enum, move to passing pointers everywhere, and
> convert the *_style objects to be pointers.  This would streamline
> things a bit; 

...

> and we could use nullptr to mean "keep the default".

Yeah, that would %pN / %p] redundant/unnecessary...

> 
> Another option would be to just add a ptr method to the _style objects,
> so instead of ui_out_style_kind::VARIABLE you'd write variable_style.ptr ().

... and could thus end up with something like:

  current_uiout->message (_("%pS%s%pS  %pS%s%pS\n"),
			  address_style.style ().ptr (),
			  tmp,
			  nullptr,
			  (msymbol.minsym->text_p ()
			   ? function_name_style.style ().ptr ()
			   : nullptr),
			   MSYMBOL_PRINT_NAME (msymbol.minsym),
			  nullptr);

If you'd like to give this a try, please do feel free to push to
the branch.

> 
> Pedro> I've not been paying much attention to the styling patches, so I can't
> Pedro> off hand tell which places would benefit the most from this.  So I just
> Pedro> grepped for _styled and replaced a couple spots.  Likely there are better
> Pedro> examples.
> 
> There's my new patch and I have one more along those lines as well, but
> a good existing one that was already deconstructed is in symfile.c:
> 
> 	  puts_filtered (_("Reading symbols from "));
> 	  fputs_styled (name, file_name_style.style (), gdb_stdout);
> 	  puts_filtered ("...\n");

So that could be either:

current_uiout->message (_("Reading symbols from %pS%s%pS...\n"),
                        file_name_style.style ().ptr (),
                        name,
                        nullptr);

or:

current_uiout->message (_("Reading symbols from %ps...\n"),
                        styled_string (ui_out_style_kind::FILENAME, name).ptr ());

or even:

current_uiout->message (_("Reading symbols from %ps...\n"),
                        styled_string (file_name_style.style (), name).ptr ());

> 
> Pedro> For the seemingly common case of printing a string variable
> Pedro> with a style, I'm thinking that a specific formatter would
> Pedro> be better.  I'll post a follow up patch for that.
> 
> I'm interested to see it.
> 
Thanks,
Pedro Alves