Translations for plugin in plugin

[sebastian.pisula]

why translations for plugins in plugin (load_plugin_textdomain) must have domain before locale ?

$mofile = $domain . '-' . $locale . '.mo';

I have plugin with domain "my-plugin" and dir languages so WP search languages/my-plugin-pl_PL.mo

In plugin lang dir should looking for languages/pl_PL.mo

[swissspidy]

That's mostly for historical reasons I think and not something that you should worry about because

a) inside wp-content/languages domain-locale.mo totally makes sense.
b) every plugin on dotorg should use language packs
c) load_plugin_textdomain() is therefore needed anymore with 4.6+
d) changing this for no reason would negatively impact performance because of additional file existence checks.

[dd32]

I agree that this isn't something we should change, although for plugins which bundle their own translations it means that they've got longer filenames, it doesn't cause any issue and supporting locale-only.mo would require extra filesystem checks for no tangible benefit.