Shortcuts for accents in \metrics

A line like

\metrics{_ _ _ u u _ _ _ _ _ u u _ _}
   {Qu\acct{i}n \acct{e}t mer-c\acct{u}-ri-um mu-t\acct{a}-to n\acct{o}-mi-ne d\acct{i}-cunt}

is quite confusing so a shorter way for accents would be nice to have. E.g. by using active characters:

\acct{a}   ——>  °a
\acct{ae}  ——>  °{ae}
\lng{a}    ——>  _a
\lng{ae}   ——>  _{ae}
\brv{a}    ——>  ^a
\brv{ae}   ——>  ^{ae}

The above line would become

\metrics{_ _ _ u u _ _ _ _ _ u u _ _}
   {Qu°in °et mer-c°u-ri-um mu-t°a-to n°o-mi-ne d°i-cunt}

Additionally active characters for bows would be also great:

coel\bow{um e}st  ——> coel(um e)st

In that case only ( has to be active and ) part of the parameter definition.

What about fine tuning in this cases? It should be no problem if \let is used, except for \bow …

Commands to (de)activate this for regular text would be also good to have

In general the should be two package options to explicitly active the active characters to prevent bad interactions with other packages:

Check interaction with babel’s active characters!

tweh / metrix