On 7/1/2021 2:36 PM, David Storrs wrote:
What is the best way to pass a function into a child `place`?
1. just define the functions in a context the place can see
2. send the name of a local file for the recipient to dynamic-require
3. send the definition file for the recipient to save locally and
dynamic-require
4. define the function(s) with serial-lambda and serialize / deserialize
I've got a server function that accepts a dispatch function as one of
its arguments and I need to be able to run the server in a separate
`place` (in the dynamic-place sense) because it's part of a GUI
application. [details]
Not a problem if using /dynamic/ (thread in same process) places.
See
https://docs.racket-lang.org/reference/places.html
https://docs.racket-lang.org/reference/places.html?q=place#%28part._places-syntax%29
I considered passing a string or symbol list and then eval'ing it in
the child place. I immediately rejected this idea and told my brain
that it was being bad and it got no cookies.
You /can/ do that ... but you don't ever have to stoop to eval.
At this point my only remaining idea is to place-channel-(put/get) a
module name that can be dynamic-required in the child place in order
to get the dispatch function. Is there a better way?
Depends on whether you're using /dynamic/ (same process) or
/distributed/ (separate process) places.
With dynamic places you can (often) just provide the code for the place
to execute. For complicated things you may have to use
serial-lambda/serialize/deserialize, but often you can simply provide
the necessary functions in context.
[details]
The Racket GUI library has an issue where e.g. launching an 'Open
File' dialog will freeze all of Racket until the user closes the
dialog. This can cause the server to time out. Since it's all of
Racket that's being frozen and not just the current thread it's
necessary to put the server code into an entirely different `place`.
And invalidating any part of the visible window does the same thing
until the window is redrawn.
George
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