compile/decorate-subject

Syntax: (decorate-subject DECORATOR SUBJECT), where the decorator’s shape selects the arm:

Decorator	Expands to
(let BINDINGS)	(let BINDINGS SUBJECT)
(with BINDING)	(with BINDING SUBJECT)
(parameterize PARAMS)	(parameterize PARAMS SUBJECT)
(call-with BINDING)	a function that enters (with BINDING ...) around each call of SUBJECT
(call-parameterize PARAMS)	a function that enters (parameterize PARAMS ...) around each call
entry-point	SUBJECT, after binding it as the module’s __entry__
anything else	(DECORATOR SUBJECT)

Behaviour: Applies one decorator to a subject form. A body-less extent form, let, with, or parameterize, is completed by grafting the subject in as its body, so the extent spans the subject’s evaluation. The call- forms instead wrap the subject in a forwarding function that establishes the extent per invocation and copies the callable’s metadata through decorate-wraps, which is functools.update_wrapper. When the subject is a coroutine function, the call- wrapper is one too, so inspect.iscoroutinefunction reports True for it. entry-point binds the subject as the module’s __entry__, the function the launcher calls when the module runs as a program, and delivers it unchanged. Any other decorator expression is evaluated and called on the subject.

New shape arms are added with extend-syntax and are tried before the invocation arm.

Examples:

>>> (macroexpand-1 '(decorate-subject (let [[c 0]]) subject))
(let [[c 0]] subject)
>>> (macroexpand-1 '(decorate-subject d fn))
(d fn)

@let [[count 0]]
def tick []:
  incr! count
  count

tick closes over a private count. See Decorators for the families and the timing of each.