here - Stefan-Marr.de

5.2. Design of the OMOP
set of mechanisms satisfies the ownership requirement and provides
a way to adapt language behavior on an object level.
By requiring that all objects have an owner it becomes possible to adapt
language behavior in a uniform way for all objects in the system. For
instance, domain objects themselves are owned by a domain. In the normal
case it is a standard domain that represents the language behavior
of the language implemented by the VM.
Thread is the unit of execution. The enforced bit indicates whether it executes
enforcing the semantics of domains, i. e., whether the intercession
handlers are triggered or not. Each thread is said to run in the context
of one specific domain. If a thread attempts to resume execution in a domain,
the corresponding #requestThreadResume: intercession handler
can be used to implement custom policies, for instance to prevent execution
of more than one thread at a time. #evaluateEnforced: enables
an existing thread to change the execution domain for the duration of
the execution of the block. During the evaluation, guarantees are enforced,
i. e., the corresponding flag in the thread is set. #spawnHere:
creates a new thread in the given domain and starts its execution, iff
#requestThreadResume has not specified a contradicting policy. These
mechanisms are necessary to satisfy the managed execution requirement.
Method representations can contain an additional bit to indicate that a particular
method is always to be executed in the unenforced mode. This
gives more flexibility to control enforcement. If the bit is set, the
thread executing the method will switch to execute in unenforced mode,
i. e., at the meta level. If the bit is not set, the thread will maintain the
current execution mode.
Read/Write operations of object fields are delegated to the #readField:of:
and #write:toField:of: intercession handlers of the owning domain.
The domain can then decide based on the given object and the field
index, as well as other execution state, what action needs to be taken.
This satisfies the managed state requirement. Note, the intercession
handlers are only triggered while the thread executes in the enforced
execution mode.
Method Execution is represented by the #requestExecOf:on:with:lkup: intercession
handler. It enables the domain to specify language behavior
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