How to set tabline in Lua?

[otakutyrant]

For convenience of cross-probjects development, I want tabpages show project names directly. So I consulted this QA and add this code in my editor.lua which will be loaded by init.lua. But I am not familiar with Lua syntax, I am not sure whether '%!v:lua.project_name()' works. It seems not work that all tabpages still show like ~/P/N/pyproject.toml rather than the project directory name New_Words_loss.

-- ## Tabline, defines how tabpages title looks like
-- For convenience of cross-probjects development, show project names directly.
function project_name()
    local tab_num = vim.fn.tabpagenr()
    local win_num = vim.fn.tabpagewinnr(tab_num)
    local working_directory = vim.fn.getcwd(win_num, tab_num)
    return vim.fn.fnamemodify(working_directory, ":t")
end
vim.t.tabline = '%!v:lua.project_name()'

[haolian9]

:h 'tabline' shows it is a global option, so try vim.go

[otakutyrant]

Thank you! I fixed the bug.

[otakutyrant]

I read the document again and found out I cannot use the code from the QA immediately. After struggling with Lua codes I finnaly made it:

-- ## Tabline, defines how tabpages title looks like
-- For convenience of cross-probjects development, show project names directly.
function MyTabLine()
    local tabline = ""
    for index = 1, vim.fn.tabpagenr('$') do
        -- select the highlighting
        if index == vim.fn.tabpagenr() then
            tabline = tabline .. '%#TabLineSel#'
        else
            tabline = tabline .. '%#TabLine#'
        end

        -- set the tab page number (for mouse clicks)
        tabline = tabline .. '%' .. index .. 'T'

        local win_num = vim.fn.tabpagewinnr(index)
        local working_directory = vim.fn.getcwd(win_num, index)
        local project_name = vim.fn.fnamemodify(working_directory, ":t")
        tabline = tabline .. " " .. project_name .. " "
    end

    -- after the last tab fill with TabLineFill and reset tab page nr
    tabline = tabline .. '%#TabLineFill#%T'

    -- right-align the label to close the current tab page
    if vim.fn.tabpagenr('$') > 1 then
        tabline = tabline .. '%=%#TabLine#%999Xclose'
    end

    return tabline
end
vim.go.tabline = "%!v:lua.MyTabLine()"