Rainer Blome wrote:

[ | :element. | element ifTrue: 'OK' False: 'Huh?' ] value: true
=> 'OK'.

Remember that there are really four objects involved in every block use: the block object itself which is a literal of the current method, a block activation which is what is actually pushed on the stack when the bytecode to push the block is executed (an implicit cloning much like what happens when methods are fetched from slots), a method (called value, value: or etc...) which holds the code that is listed above and a method activation that actually executes the code when the value message is sent to the block activation.

This means that the code above is roughly like

( | lexicalParent. parent* = blockParent. value: = ( | :element | element ifTrue: 'OK' False: 'Huh?' ). | ^ clone lexicalParent: _CurrentActivation ) value: true

The details aren't important, just the fact that when you write [...] in your code you are actually writing the body of a value method.

[ | :element*. | ifTrue: 'OK' False: 'Huh?' ] value: true
=> Syntax error.

Every method activation has an implicit :self* slot, except for the method activation of the value method of a block that has a :<lexicalParent>* slot instead. These slots can't be produced from the normal Self syntax, but only created by the virtual machine.

[ | :element. environment*. |  environment: element.
  ifTrue: 'OK' False: 'Huh?' ] value: true
=> Lookup error: ifTrue not found.

The environment* slot is actually a slot in the value method, and its clone the value method activation. I can't test this, but I would bet that no method/method activations can have working dynamic parent slots. From the language definition they should, so it looks like an implementation error. I don't think the effort to "fix" this error is worth it, however, so I would suggest that you stick with other solutions to your problem.

-- Jecel