2
Issues:
•Intrusive in API: Burying the async work partly inside
the APIs changes/bloats
the APIs and can duplicate code.
•Complex for callers: Instead of calling one function, the
user must
call two functions, manage intermediate state, and write an additional function of his own
for the callback.
•Hand-coded pattern, no
language support/checking:
The pattern
may vary; consistency depends on manual discipline. This approach has more potential points
of failure where the programmer can go wrong.
–DG example: “Do ensure that the EndMethodName method is always called even if the operation is known to
have already
completed. This allows exceptions to be received and any resources used in the async operation to
be freed.”
Comparison:
FX Async Pattern (2)