Refactoring in Vim

I agree with the 'Vim is not an IDE' paradigm. But there are times when there isn't an IDE. Here's what I use in those situations:

Disclaimer: The ubiquity of Language Server Protocol servers, linters and fixers since I wrote this have also brought some great refactoring capabilities to Vim (and other editors). IMO they are a long way from equaling the capabilities of a purpose-built IDE (I prefer ALE and nvim-lspconfig for these kinds of features). See other answers on this question for more info!

:grep, :vimgrep, :GrepperAg, :Ggrep

Refactoring that has more to do with regular replacements I usually use :grep on my project tree and then record a macro to do the refactor - :g and :s are no brainers. Usually it'll let me quickly modify a large number of files with very little effort. Honestly, I use this method more than any other.

Depending on your workflow the built-in commands might be slow/inconvenient. If you use git, then you'll wanna use the excellent Fugitive plugin and its :Ggrep command to only search files checked into git. I also like the vim-grepper because it is search-tool-agnostic (supports ag, sift, ripgrep, etc) and speedy.

:argdo, :cdo, and :bufdo

:cdo and :argdo are handy to execute vim commands over a set of files.

command line

When it's harder to determine the list of files that need changes via :vimgrep I resort to the command line grep/find commands to more closely curate the list of files that I need to refactor. Save the list to a text file and use :e and a mashup of macro recordings to make the changes I need to make.

I find that the less rusty I keep my macro recording skills the more useful I find Vim for refactoring: feeling comfortable saving/restoring from registers, incrementing/decrementing register counter variables, cleaning/saving macro recordings to file for later use, etc.

Update

Since writing this more videocasts for the methods I describe have been published on vimcasts.org (I encourage you to watch ALL the Vimcasts!). For refactoring watch these ones:

Substitution with :Subvert
Project wide search/replace
Search multiple files with :vimgrep
Use :argdo to change multiple files

Vimgolf is also a great way to practice.

Language Server Protocol (LSP)

The Language server protocol contains the feature for smart renaming of symbols across a project:

https://microsoft.github.io//language-server-protocol/specifications/specification-3-14/#textDocument_rename

For example following language server support this:

Clangd for C++
ccls for C/C++/Objective-C
Eclipse.jdt.ls for Java
pyls (with rope) for Python
tsserver for TypeScript
Solargraph for Ruby
gopls official lsp for Go (alpha stage in Nov 2019)
texlab for LaTeX

You can find more language servers under https://langserver.org/.

Vim

A vim editor client is necessary to use them within vim. Following options exist:

LanguageClient-neovim (requires rust) suggests the mapping:

 nnoremap <silent> <F2> :call LanguageClient_textDocument_rename()<CR>

coc.nvim (requires node.js) suggests the mapping:

 " Remap for rename current word
 nmap <leader>rn <Plug>(coc-rename)

Ale has
```
 nnoremap <silent> <Plug>(ale_rename) :ALERename<Return>
```
Ale does not define any keybindings. This has to be done by the user.
vim-lsp provides following command
```
 :LspRename
```
Similar to Ale no mapping is suggested. However, of course you can define one as following
```
 nmap <leader>r <plug>(lsp-rename)
```
(<leader>r is to be replaced by your choice; I do not know one which most plugins agree on)
vim-lsc has a default mapping:
```
 'Rename': 'gR'
```

See also YouCompleteMe which facilitates LSPs as well.

Neovim

Neovim has initial builtin support for lsp since 13.11.2019

See for common configurations of LSPs the project nvim-lspconfig which suggests <space>rn as a mapping for vim.lsp.buf.rename().

Other Refactorings

I do not know if there are plans for the LSP protocol to support more complex refactorings, such as changing class structure, adding parameters to methods/functions or moving a method to a different class. For a list of refactorings see https://refactoring.com/catalog/.

Python

For the python language following plugins provide 'smart' renaming capabilities for vim:

jedi-vim (github) <leader>r
ropevim (github) CTRL-c r r
python-mode (github) :h pymode-rope-refactoring

C-Family

Try the plugin Clighter for rename-refactoring for the c-family. It is based on clang, but there are limitations and the plugin is marked as deprecated.

Suggested mapping by Clighter is
```
 nmap <silent> <Leader>r :call clighter#Rename()<CR>
```
Note, the successor plugin clighter8 has removed the renaming functionality in the commit 24927db42.
If you use neovim, you can take a look at the plugin clamp. It suggests
```
 nmap <silent> <Leader>r :call ClampRename()<CR>
```