The "advice" feature lets you add to the existing definition of a function, by wrapping around the original function a "piece of advice".
Each piece of advice receives the original function and arguments; its result is returned to the caller as if from the original function.
A function may have multiple pieces of advice, which are composed by nesting earlier advice within later advice.
(Info-goto-node "(elisp)Advising Functions")
val add :
?docstring:string ->
?interactive:string ->
Core_kernel.Source_code_position.t ->
'a Value.Type.t ->
Symbol.t ->
(inner:(Value.t list -> Value.t) -> inner_args:Value.t list -> 'a) ->
for_function:Symbol.t ->
unitadd ?docstring ?interactive here return_type advice_name f ~for_function defines function advice_name with body f and adds it as advice on for_function.
(describe-function 'advice-add)