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NICHOLAS85 / z-a-eval

A Zsh-Zinit annex (i.e. an extension), which caches arbitrarily slow command output to speed up shell startup.
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shell-plugin shell-script terminal zinit zinit-annex zsh zsh-plugin

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z-a-eval

Introduction

A Zsh-Zinit annex (i.e. an extension) that provides functionality, which allows to:

  1. Cache the output of arbitrarily slow initialization command to speed up shell startup time.

Installation

Simply load like a regular plugin, i.e.:

zinit light NICHOLAS85/z-a-eval

After executing this command you can then use the new ice-mods provided by the annex.

How it works

The output of a slow initialization command is redirected to a file located within the plugin/snippets directory and sourced while loading. The next time the plugin/snippet is loaded, this file will be sourced skipping the need to run the initialization command.

Ice Modifiers Provided By The Annex

There is 1 ice-modifier provided and handled by this annex. They are:

  1. eval'' – creates a cache containing the output of a command.

The ice-modifier in detail:

1. eval'[!]{command}…'

It creates a cache in the plugin/snippets root directory which stores the commands output. This cache is regenerated when:

The optional preceding ! flag means to store command output regardless of exit code. Otherwise eval'' will avoid caching ouput of code which returns a non-zero exit code.

Example Invocations

## Without z-a-eval
zinit ice as"command" from"gh-r" mv"zoxide* -> zoxide"  \
      atclone"./zoxide init zsh > init.zsh"  atpull"%atclone" src"init.zsh" nocompile'!'
zinit light ajeetdsouza/zoxide

## With z-a-eval
zinit ice as"command" from"gh-r" mv"zoxide* -> zoxide" \
      eval"./zoxide init zsh"
zinit light ajeetdsouza/zoxide
## Without z-a-eval
zinit ice atclone"dircolors -b LS_COLORS > init.zsh" \
    atpull"%atclone" pick"init.zsh" nocompile'!' \
    atload'zstyle ":completion:*" list-colors “${(s.:.)LS_COLORS}”'
zinit light trapd00r/LS_COLORS

## With z-a-eval
zinit ice eval"dircolors -b LS_COLORS" \
    atload'zstyle ":completion:*" list-colors “${(s.:.)LS_COLORS}”'
zinit light trapd00r/LS_COLORS
## Without Zinit
if [[ "${+commands[kubectl]}" == 1 ]]; then
    eval $(kubectl completion zsh)
fi

## With Zinit and z-a-eval
## Updated during `zinit update`
zinit ice id-as"kubectl_completion" has"kubectl" \
      eval"kubectl completion zsh" run-atpull
zinit light zdharma/null

See https://github.com/NICHOLAS85/z-a-eval/issues/2#issuecomment-793374468 for more examples.

Additional Zinit commands

There's an additional Zinit command that's provided by this annex –recache. It recaches all your plugins/snippets eval outputs on demand. Useful for when you change the value of the eval'' ice but do not want to redownload the plugin/snippet to update its ices, or rm the cache manually:

recache-invocation

Available options are:

zinit recache [plugin/snippet]

When run without an argument, it will iterate through all plugin/snippets who have caches and regenerate them based on the current value of eval''. If eval'' is missing, it will simply delete the cache file.

When run with a plugin/snippet argument, it will only regenerate that single plugin/snippets cache based on the current value of eval''.

Zinit tab completion support

Zinit currently does not support extending the subcommands available via tab completion. I however, have implemented experimental support for this which should be duplicable across any annex.

In order to enable tab completion for the new subcommand set the value Z_A_USECOMP=1 somewhere before loading this plugin. For example:

zinit atinit'Z_A_USECOMP=1' light-mode for NICHOLAS85/z-a-eval

If you're interested in seeing how it works some more detail can be seen at the bottom of z-a-eval.plugin.zsh. I'd love to hear feedback on its implementation.