is-installed for themes and plugins should only support one language code

[Dominik Schilling]

2660f96 added support for is-installed to language core and follows the core/plugin/theme commands. All the commands only support one object to check for. This makes sense because the return value is only 0 or 1.

In 51a5ff0 this was also added to language plugin/theme but in this case it also supports passing multiple language codes. This made the genreal behaviour of is-installed inconsistent and I'm wondering why someone would use this since you'd never know which language code isn't installed.

[Alain Schlesser]

If your use case is to verify whether all requirements are set and bail if not, then this can do it in one command.

For quick & dirty setup, for example, you could do something like this:

if ! wp plugin is-installed gutenberg en_US de_DE fr_FR nl_NL; then
    wp plugin install gutenberg en_US de_DE fr_FR nl_NL
fi

Otherwise, you are still able to only pass in a single plugin/theme at a time.

So yes, while it is debatable whether one can make proper use of this, it is not an error per se, and the more useful behavior is not blocked because of it.

[Alain Schlesser]

Of course this makes it inconsistent with the existing core language is-installed command then. So we should discuss whether we change one or the other to make them more consistent.

[Pascal Birchler]

Hmm yeah I probably should only have added support for one locale to be passed.