The Inbox: Kernel-ct.1357.mcz

A new version of Kernel was added to project The Inbox:
http://source.squeak.org/inbox/Kernel-ct.1357.mcz

==================== Summary ====================

Name: Kernel-ct.1357
Author: ct
Time: 28 October 2020, 9:30:35.577652 pm
UUID: efd94ae0-26ab-0c4f-b854-52f414ff2d3e
Ancestors: Kernel-eem.1354

Implement missing simulation of objects as methods.

In the past, it was not possible to debug/simulate code that used objects as methods properly. (Thanks to Marcel for the hint!) This very simple commit adds support of the OaM protocol [1] to the simulation machinery. Now you can debug all tests in TestObjectsAsMethods as you would expect, instead of crashing your image!

Update: Uploaded a third time, this time with Kent Beck block formatting preserved.

[1] "The [Objects as Methods] contract is that, when the VM encounters an ordinary object (rather than a compiled method) in the method dictionary during lookup, it sends it the special selector #run:with:in: providing the original selector, arguments, and receiver.". DOI: 10.1145/2991041.2991062.

=============== Diff against Kernel-eem.1354 ===============

Item was changed:
  ----- Method: Context>>send:to:with:lookupIn: (in category 'controlling') -----
  send: selector to: rcvr with: arguments lookupIn: lookupClass
+ "Simulate the action of sending a message with selector and arguments to rcvr. The argument, lookupClass, is the class in which to lookup the message. This is the receiver's class for normal messages, but for super messages it will be some specific class related to the source method."
- "Simulate the action of sending a message with selector and arguments
- to rcvr. The argument, lookupClass, is the class in which to lookup the
- message.  This is the receiver's class for normal messages, but for super
- messages it will be some specific class related to the source method."
 
  | meth primIndex val ctxt |
  (meth := lookupClass lookupSelector: selector) ifNil:
  [^self send: #doesNotUnderstand:
  to: rcvr
  with: {(Message selector: selector arguments: arguments) lookupClass: lookupClass}
  lookupIn: lookupClass].
+
+ meth isCompiledMethod ifFalse:
+ ["Object as Methods (OaM) protocol: 'The contract is that, when the VM encounters an ordinary object (rather than a compiled method) in the method dictionary during lookup, it sends it the special selector #run:with:in: providing the original selector, arguments, and receiver.'. DOI: 10.1145/2991041.2991062."
+ ^ self send: #run:with:in:
+ to: meth
+ with: {selector. arguments. rcvr}].
+
+ meth numArgs = arguments size ifFalse:
+ [^ self error: ('Wrong number of arguments in simulated message {1}' translated format: {selector})].
- meth numArgs ~= arguments size ifTrue:
- [^self error: 'Wrong number of arguments in simulated message ', selector printString].
  (primIndex := meth primitive) > 0 ifTrue:
  [val := self doPrimitive: primIndex method: meth receiver: rcvr args: arguments.
+ (self isPrimFailToken: val) ifFalse:
- (self isPrimFailToken: val) ifFalse:
  [^val]].
+
  (selector == #doesNotUnderstand: and: [lookupClass == ProtoObject]) ifTrue:
+ [^ self error: ('Simulated message {1} not understood' translated format: {arguments first selector})].
+
- [^self error: 'Simulated message ', arguments first selector, ' not understood'].
  ctxt := Context sender: self receiver: rcvr method: meth arguments: arguments.
+ (primIndex notNil and: [primIndex > 0]) ifTrue:
- primIndex > 0 ifTrue:
  [ctxt failPrimitiveWith: val].
+
  ^ctxt!