Block activation
- When literal block is compiled, a block object b1 is created with value method slot and parent* slot, set to traits block.
- When expression containing the reference to the block is evaluated, the block is cloned to give an object b2, with an extra hidden slot containing a reference to the current activation, m .
- When b2 is activated (using value ), its method is cloned, and a hidden parent installed by copying the reference to m .
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Block activation
Block activation is similar to method activation, except that there is an extra stage.
First, a block object is created at compile time. This has a parent* slot that refers to
traits block, and a value method (appropriate to the number of arguments), with the
block's code as the method body.
When the expression containing a reference to this block is evaluated, the block is
cloned, and the clone is given a hidden slot that refer's to the current activation
object.
When the block's method is activated (via a value message), the method is cloned
and a hidden parent slot is added, containing a reference to the activation object
saved in the previous step (not a self slot, as per methods). This allows the block to
access the slots of enclosing block's and the outermost method (lexical scoping).
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