- Method `+=
this_program `+=(zero arg, zero ... rest)
Destructive addition/concatenation callback.
This is used by `+. It's called with any arguments that follow this object in the argument list of the call to `+. It should update this object to represent the addition/concatenation between it and the arguments in the order they are given. It should always return this object.
This function should only be implemented if lfun::`+() also is. It should only work as a more optimized alternative to that one, for the case when it's safe to change the object destructively and use it directly as the result.
This function is not an lfun for the
+=operator. It's only whether or not it's safe to do a destructive change that decides if this function or lfun::`+() is called; both the
+operator and the
+=operator can call either one.
- See also