Adding alert as new message type

[sluedecke]

In case of an unexpected events, I would love to display a warning to the user, which simply needs to be "confirmed" for the programm to move on.

The workaround I use is a selection with "OK" as single option, but this is a bit hacky.

I kindly request to add alert as a new interaction option to dialoguer. One can use the pull request, but I probably messed the return types up ...

obsoletes #287

[pksunkara]

Why can't confirm be used?

[sluedecke]

I tried, but it appeared to me that all ways to use Confirm present the user with some kind of choice. There is always the y/n rendered and I am looking for an alert which can only be acknowleged.

This can be done with Confirm and setting a default, but having the 'y/n' suggests that there is a choice if there actually is none.

[pksunkara]

Instead of adding a new prompt, can you please modify the confirm prompt with an extra option?

[sluedecke]

Sure. But I wonder if that would introduce a lot of "if-clauses" into the code making it more complex than needed. Right now I think a new prompt has these advantages:

• Clearer API - it is focussed on the use case alert only. How to interpret the options report, default, show_default and wait_for_newline for an alert?
• Clearer code - adding it to confirm would make the routines interact_on, theme/mod.rs::format_confirm_prompt and theme/colorful.rs::format_confirm_prompt more complex.

Probably it is just a mattter of coding style, what do you think?