Support zsh and other shells

[dimo414]

Original report by Michael Diamond (Bitbucket: dimo414).

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@bedge asked for zsh support in #15. Supporting other shells would be nice, but would require user contributions as it's not a priority for me personally. If anyone's interested in contributing feel free to reach out here.

[KTSCode]

Just switched to zsh from bash because I'm using MacOS and didn't want to keep using an outdated version of bash. I'm really sad to be losing bash-cache functionality it's quite helpful in my tmux status bar scripts which hit external APIs.

What steps would be necessary to make bash-cache work for zsh?

[dimo414]

FWIW it's pretty easy to get a modern bash running on macOS; with homebrew it's just brew install bash.

I really don't know how much work would be involved. As I don't use zsh I'm not sure exactly which bash-isms would need to be redesigned (or the best way to do it). But I wouldn't be surprised if it's non-trivial, since bash-cache does some distinctly power-user things. Some potential issues that stand out:

• bc::copy_function enables the decorator pattern bash-cache uses
• The function-template pattern isn't strictly necessary but I'd be disappointed to have to remove it
• This descriptor juggling is important for safe reads
• bc::locked_cache requires Bash 4.1's anonymous descriptor support

[dimo414]

I'm in the process of publishing bkt, a standalone binary that's spiritually similar to bash-cache but intended for subprocesses instead of shell functions. Although it fits a slightly different niche than caching shell functions it may still be useful for zsh et al. users. If you'd like to try it out I'd welcome any feedback.