Dan, Below are some questions about this ...
> -----Original Message----- > From: Dan Sugalski [mailto:[EMAIL PROTECTED]] [snip] > Objects, as far as I see it, have the following properties: > > 1) They have runtime-assignable properties Terminology question: what is the difference between a property and an attribute? Perhaps the answer could go in the glossary. [snip] > #3 Since each class has a PMC type, we just need to associate the PMC > type with the data a class needs. Also pretty much no big deal, and > something we already have facilities for. So, while there may be exceptions, generally all classes will be instances of the Class PMC, true? [snip] > The call/jmpmeth opcodes either make a returnable or non-returnable > method call. They fetch the function pointer from the object PMC and > either dispatch to it or save the current state and jsr to it. Note > that you can't jmpmeth into a C-implemented method, so no tail > calling into those without some wrapper opcodes. The registers still > need to be set up appropriately, just like with a regular sub call. So the call opcode takes a method name or offset and calls a vtable method to find the method and then invokes it? > The find_method vtable entry should die, and be replaced with a plain > method entry. This should return either the address of the start of > the method's bytecode, or NULL. The NULL return is for those cases > where the method actually executed via native code, and thus doesn't > have to go anywhere. If an address is returned it's expected that the > engine will immediately dispatch to that spot, obeying parrot's > calling conventions. Not sure what this means, does it mean that there is a method named "find_method" accessed something like call Px, Py, "find_method" which I can then call to find the method or am I off? [snip] > The structures: > > *) Attr PMCs have an array off their data pointer. > > *) Classes are variants of Attr PMCs. They have the following > guaranteed attributes in slots: > > 0) Hash with class name to attribute offset I am not sure what this means, Don't we already have the class and it's attributes if we are accessing these slots? > 1) Hash with attribute name to attribute offset (relative to the > offset found from the hash in slot 0, generally known at > compile time, but introspection is nice) > 2) Integer number of attributes this class has > 3) Notification array Do we store ptrs to parent classes in one of these slots? Also Can I access slots like: set Px, Py[1] # store the name to offset hash in Px [snip] So to sum up we need the following pmc's: pmclass Ref { data is a pointer to an object } pmclass Attr { data is an array of attributes } pmclass Class extends Attr { } pmclass Object { this was not explained, but I guess it at least has a reference to a Class and field data ??? } Does that cover it? -- Jonathan Sillito
