On Tue, Jan 20, 2015 at 7:39 PM, Nicolas Cellier nicolas.cellier.aka.nice@gmail.com wrote:
2015-01-19 15:41 GMT+01:00 Craig Latta craig@netjam.org:
Okay, I'll add both of the execution-driven imprinters to therepository. They're called "active" and "passive" imprinting.
Active imprinting is directed by the system that initially has thedesired code. An ActiveImprintingServer has clients in the systems which will receive the code. Every time the server system runs a method in a certain process, it imprints that method onto each of the clients. One use case for this is giving the code of a demo to an audience as you run it.
Passive imprinting is directed by the system that wants the code.The target system makes a remote-messaging connection to a system which has the code, and runs an expression which will use the code. Every time a method is missing from the target system (in any process), the target system requests the missing method from the provider system, installs it, and retries running that method.
I have imprinted the exception-handling system, the compiler, andthe class builder with both approaches.
In this scheme, something is striking me. Some images share some code (classes, compiledMethods) But what about code mutations/updates?
Without such mutations, is it still Smalltalk?
Without active imprinting, such mutations might not be obvious to propagate (for example a subclass now overrides a message of super)
And since you import class builder and compiler in the target, on what purpose? Is the target going to change a class locally? What if it then imports incompatible methods from provider? Or is the goal to just replicate some mutations from the provider?
Maybe the scheme is more interesting for deployment of static code, but I'm curious to know if ever live updates would still be possible...
The particular scenario I was dreaming of would never have changes made to the imprinted images. At worst, the source Caddilac image might be have a patch applied in production, in which case it would need some way to invalidate the updated methods in all clients...