37 lines
1.6 KiB
Ruby
37 lines
1.6 KiB
Ruby
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# A Frame is set up by functions that use local variables or temporary variables
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# in fact temporary variables are local variables named by the system
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# It allows for access to those variables basically
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# A Message and a Frame make up the two sides of message passing:
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# A Message (see details there) is created by the sender and control is transferred
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# A Frame is created by the receiver
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# PS: it turns out that both messages and frames are created at compile, not run-time, and
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# just constantly reused. Each message has a frame object ready and ist also linked
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# to the next message.
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# The better way to say above is that a messages is *used* by the caller, and a frame by the callee.
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# In static languages these two objects are one, because the method is known at compile time.
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# In that case the whole frame is usually on the stack, for leaves even omitted and all data is
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# held in registers
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#
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# In a dynamic language the method is dynamically resolved, and so the size of the frame is not
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# know to the caller
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# Also exceptions (with the possibility of retry) and the idea of being able to take and store
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# bindings make it, to say the very least, unsensibly tricky to store them on the stack. So we don't.
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# Also at runtime Messages and Frames remain completely "normal" objects. Ie have layouts and so on.
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# Which resolves the dichotomy of objects on the stack or heap. Sama sama.
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module Parfait
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class Frame < Object
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attribute :next_frame
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def self.offset
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Space.object_space.get_class_by_name(:Frame).object_layout.object_instance_length
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end
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end
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end
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