Raise exception for reserved words (namely flash)

[cllns]

This issue started as a request for documentation that flash is a reserved word when using Hanami::Action::Session: hanami/hanami#595

Instead of just documenting it, we should help the developer by raising an exception when they try to use any reserved word.

One reserved word is flash but we should make sure all reserved words are covered.

(Thanks for the original issue @rafaels88)

[nickskalkin]

If nobody minds, I'll get this issue. But I have no idea how to implement it yet, hah

[jodosha]

@Vladimirich Please do.

[akhramov]

@Vladimirich are you still up for it?

[akhramov]

Hi everyone. I think we can go with guard module. The idea behind is dead simple:

• Create a module implementing #expose method, which raises an exception if given list of words contains one or more reserved word. Otherwise it calls super.
• Prepend this module to an action.
• Introduce an alias method for #expose (#expose! or #_expose) for internal usage. This alias won't be watched by the guard so no exceptions are raised.

I have created a proof of concept can be found here.

Any thoughts?

Thank you.

[nickskalkin]

@akhramov , yep, sorry, was on vacation and forget to inform about it in this issue

[nickskalkin]

@akhramov , but if you already did something you can take this issue. What do you think?

[akhramov]

@Vladimirich let us try, thanks.