quand j'en aurai fini avec tout cela

Question

In the writing challenge "At Uncle Robert's 70th birthday" we are asked to translate "when I'm done with all that".

The suggested answers both use "en". E.g. "quand j'en aurai fini avec tout cela".

I wonder why "en" is required? I expect it to replace "de qqch" but in this sentence isn't that role - specifying what is being finished - supplied by "avec tout cela"?

Is there a lesson on Kwiziq that gives an example of this usage? It is not really included in En can replace de + [phrase] (French Adverbial Pronouns)

Accepted Answer

Hi David,
The 'en' of the verbal expression -
En avoir fini avec = to be done with 
is idiomatic like in 's'en aller'.
Hope this helps!

Answer

Ok, thank you

Answer

I just encountered another example of this idiomatic expression while reading "Harry Potter et la Chambre des Secrets".

"Mais ne vous inquiétez pas, votre maître des potions sera toujours en état de vous faire cours quand j’en aurai fini avec lui."

Answer

Super!