Special treatment for namepsace prefixes in Emacs hippie-expand
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Special treatment for namespace prefixes in Emacs hippie-expand.


(require 'hippie-namespace)
(global-hippie-namespace-mode 1)
(define-key global-map (kbd "M-/") 'hippie-expand)
;; type hi [M-/]     ; The first one or two letters of a namespace
                     ; found in the current buffer, followed by the
                     ; key bound to `hippie-expand'.


The purpose of hippie-namespace is to save typing.

Enabling this minor mode adds a limited number of very common prefixes to the hippie-expand expansion list. These prefixes (deduced from buffer content) will be the first completions considered.

Furthermore, hippie-namespace completions are treated specially: when hippie-expand proposes a namespace completion, it will not cycle. Instead, the namespace completion is implicitly accepted, and further invocations of hippie-expand will build on the expansion.

For example, the common prefix of all symbols in this library is "hippie-namespace-". If, while editing this library, the user types "hi [hippie-expand]" or even just "h [hippie-expand]", the full prefix is expanded.

"hi [hippie-expand] [hippie-expand] ..." will then cycle through all completions which match the prefix.

This mode makes more sense for some languages and less sense for others. In most languages, the declared "namespace" is infrequently used in its own context. (For Emacs Lisp that is not the case.)

Note that you should also have hippie-expand bound to a key. Many people override dabbrev expansion:

(define-key global-map (kbd "M-/") 'hippie-expand)

Determining Namespaces

The minor mode will examine each buffer to guess namespace prefixes dynamically. If the guess is not good enough, you may add to the list by executing

M-x hippie-namespace-add

or by adding a file-local variable at the end of your file:

;; Local Variables:
;; hippie-namespace-local-list: (namespace-1 namespace-2)
;; End:

Mode-specific namespace finders are easy to write. Search for "Howto" in the source.


Integrates with expand-region, adding an expansion which is aware of the namespace and non-namespace portions of a symbol.

See Also

  • M-x customize-group RET hippie-namespace RET
  • M-x customize-group RET hippie-expand RET


Breaks using C-u [hippie-expand] to undo. Workaround: use regular undo commands.

Compatibility and Requirements

GNU Emacs version 24.4-devel     : yes, at the time of writing
GNU Emacs version 24.3           : yes
GNU Emacs version 23.3           : yes
GNU Emacs version 22.2           : yes, with some limitations
GNU Emacs version 21.x and lower : unknown

Uses if present: expand-region