Add fallback support about diehard

[sunng87]

released in 0.3.0

[dhruvbhatia]

Thanks so much for implementing this!

Quick q re: the signature, the readme suggests the :fallback fn returns [exception value] arguments, but I seem to be getting [nil exception] instead (aka the exception is actually the second argument and the first argument always returns nil).

The readme states the return argument other than exception is meant to be the value of the previous attempt - but wouldn't this always return nil given we'd never hit the fallback criteria if the previous attempt returned a value rather than an exception?

[sunng87]

Good catch, @dhruvbhatia . That's a mistake in documentation. The first argument is return value, which is consistent with retry-if.

Because you can configure retry criteria that not only will exception cause retry, but also some return value that matches your criteria.

[dhruvbhatia]

Thanks for the quick response - that makes sense. 👍

[vendethiel]

Hey,
the fallback code uses when-let (:fallback, which means fallback falsy values, such as nil or false, can't be used (they'll be silently ignored).
This is either a bug, or something that could be documented. What do you think?

[sunng87]

@vendethiel it sounds more like a bug. We should fix it by wrapping a (some?)

[sunng87]

Fixed in a3fa30f