On Fri, 26 Sep 2014, Michael Schnell wrote:
Yesterday, I had a discussion with a colleague about programming languages.
He said that he did not like Object-Pascal / fpc because it lacks the concept
of "signals" he finds in other languages / libraries. (He is not an expert
but discusses on base of rumors he collected.)
With "signals" he meant a kind of multi-target events.
He described that multiple parts (units) of a program (or even units within a
set of sunning programs) can "subscribe" to a signal (or several of them),
and whenever anyone "rises" a signal all subscribers get notified and can
react.
Seemingly the execution line in such a "unit" might be as well the main
thread or a worker-thread (or even another task/program) and the event
handler can be defined to work on this thread (he did not elaborate if always
or optionally a newly created thread can be used).
Unfortunately I was not able to come up with a similarly powerful concept
available in fpc.
You can use the Observer pattern; it is in the classes unit.
And to be honest, this is not a language concept, but a library concept.
It can be easily implemented.
Michael.
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