spec.md
In lifecycle: Manage the Life Cycle of your Package Functions

spec() gives useful errors

Code
  spec(1)
Condition
  Error:
  ! `what` must be a single string, not a number.

Code
  spec("foo")
Condition
  Error:
  ! `what` must have function call syntax.

    # Good:
    signal_lifecycle("foo()")

    # Bad:
    signal_lifecycle("foo")

Code
  spec("foo()()")
Condition
  Error:
  ! `what` must be a function or method call.

Code
  spec("foo(arg = , arg = )")
Condition
  Error:
  ! Function in `what` (foo) must have 1 argument, not 2.

Code
  spec("foo(arg = arg)")
Condition
  Error:
  ! `what` must contain reason as a string on the RHS of `=`.

    # Good:
    signal_lifecycle("foo(arg = 'must be a string')")

    # Bad:
    signal_lifecycle("foo(arg = 42)")

Code
  spec("foo()", env = e)
Condition
  Error:
  ! Can't detect the package of the deprecated function.
  Please mention the namespace:

    # Good:
    signal_lifecycle(what = "namespace::myfunction()")

    # Bad:
    signal_lifecycle(what = "myfunction()")

spec() works with methods

Code
  spec("A$foo(bar = 1)")
Condition
  Error:
  ! `what` must contain reason as a string on the RHS of `=`.

    # Good:
    signal_lifecycle("A$foo(arg = 'must be a string')")

    # Bad:
    signal_lifecycle("A$foo(arg = 42)")