====== compsys: General setup ======

==== How to turn on the "new" completion system ====

Enter the following two commands:

<code>
autoload -U compinit
compinit
</code>

==== Enabling Caching ====

Some functions, like _apt and _dpkg, are very slow. You can use a cache in order to proxy the list of results (like the list of available debian packages).

<code>
zstyle ':completion:*' use-cache on
zstyle ':completion:*' cache-path ~/.zsh/cache
</code>

==== Helper functions ====

With helper functions, you can avoid having to complete at all in many cases, but if you do, you might want to fall into menu selection immediately and to have the words sorted by time:

<code>
xdvi() { command xdvi ${*:-*.dvi(om[1])} }
zstyle ':completion:*:*:xdvi:*' menu yes select
zstyle ':completion:*:*:xdvi:*' file-sort time
</code>

==== Subscript completion ====

when completing inside array or association subscripts, the array elements are more useful than parameters so complete them first:

<code>
zstyle ':completion:*:*:-subscript-:*' tag-order indexes parameters
</code>

==== Picking parameters by the existence of a special completer ====

in recent zsh 4.1.x only: complete the names of parameters we have special completions for in parameter assignments:

<code>
zstyle ':completion::*:(-command-|export):*' fake-parameters ${${${_comps[(I)-value-*]#*,}%%,*}:#-*-}
</code>

==== Remove trailing slashes ====

If you end up using a directory as argument, this will remove the trailing slash (useful in ln):

<code>
zstyle ':completion:*' squeeze-slashes true
</code>

==== completing on the prefix ====

How to complete in the middle of some text ignoring the suffix. (people coming from tcsh might miss this big time).

Just bind ''TAB'' to ''expand-or-complete-prefix'':

<code>
bindkey '^i' expand-or-complete-prefix
</code>

Then ''/usr/loc<TAB>ljkabcb'' completes just like if you had ''/usr/loc<TAB>''.

==== The "Why doesn't zsh's completion realize new commands?" FAQ ====

Quoting Bart Schaefer from zsh-users #8059:
> If you're using compsys, the right way to do this is by adding to your completer zstyle:

<code>
_force_rehash() {
  (( CURRENT == 1 )) && rehash
  return 1	# Because we didn't really complete anything
}

zstyle ':completion:*' completer \
  _oldlist _expand _force_rehash _complete ...
</code>

> (where "..." is the rest of whatever you already have in that style).