implement default titlestring using statusline

[josephholsten]

At the moment, when titlestring is not set, the default value is generated by accessing curbuf->b_fname, bufIsChanged(curbuf), curbuf->b_ffname & append_arg_number() (an extracted version of this is in src/nvim/title.c:113).

Unfortunately, it is not possible to reproduce this behaviour using a statusline format string. The closest might be:

:set titlestring=%t%(\ %M%)%(\ \(%F\)%)%a\ -\ VIM

where those represent the flags found in option_defs.h:

#define STL_FILENAME    't'             /* last part (tail) of file path */
#define STL_MODIFIED_ALT 'M'            /* modified flag - other display */
#define STL_FULLPATH    'F'             /* full path of file in buffer */
#define STL_ARGLISTSTAT 'a'             /* argument list status as (x of y) */

The only part which differs from the default titlestring is %F, which shows the full path of the file, including the last part (tail). The default uses the full path of the file with the part in %t and the final seperator removed.

The best way to allow for this would be to add a new statusline flag, say %d which shows the full path of the directory containing the current file.

Then, since statusline support is on all the time (according to src/nvim/version.c:140), we can simplify the implementation of maketitle() to always use the standard statusline processing.

Thoughts? Objections?

[bfredl]

Completely argree. It would be much more convenient to start customizing the titlestring if one actually could start with the default string and gradually modifying it (rather than first having to google for a workaround, that almost, but not completely, replicates the builtin behavior)
Unrelated to your point, but wouldn't it be better if the default had 'NVIM' instead of 'VIM' ?

[Billy4195]

After I traced the current titlestring document (in :help titlestring), I think this issue is done by someone else. Maybe this could be close?

[justinmk]

The only part which differs from the default titlestring is %F, which shows the full path of the file, including the last part (tail). The default uses the full path of the file with the part in %t and the final seperator removed.

This seems to mimic the default, what's missing?

set titlestring=%t%(\ %M%)%(\ \(%{expand(\"%:~:h\")}\)%)%a\ -\ NVIM