How do I customize which patterns Vim considers a definition for [d and ]d jump commands?

Explanation

Vim's [d, ]d, [D, and ]D commands search for the "definition" of the keyword under the cursor. What counts as a definition is controlled by the 'define' option — a regex pattern that must match the start of a definition line. By default this is set to ^\s*#\s*define (C preprocessor #define directives), but you can customize it per filetype to jump to function or class definitions in any language.

How it works

• [d — display the first line matching 'define' that contains the keyword
• ]d — display the next such match below the cursor
• [D — list all matching definition lines in a new window
• [<C-d> — jump to the first matching definition
• The 'define' pattern is matched against entire lines; set it to the prefix that marks a definition in your language

Example

For Python, set 'define' to match function and class definitions:

autocmd FileType python setlocal define=^\\s*\\(def\\|class\\)

With the cursor on my_func, pressing [d will show:

found in current file
  42: def my_func(x, y):

For Go, you might use:

autocmd FileType go setlocal define=^func

Tips

• Check the current value with :set define?
• Use setlocal in FileType autocmds to avoid leaking settings across filetypes
• These commands search both the current buffer and files in 'include' paths
• Pairs naturally with 'include' and 'includeexpr' for cross-file definition lookup
• In Neovim with LSP, these commands are often superseded by gd, but [d works without any language server