Man, this is exciting! A strong reason to already switch to Pharo 4 :)
Doru On Mon, Jul 21, 2014 at 11:28 AM, Marcus Denker <[email protected]> wrote: > Hello, > > One of the questions with having meta objects for variables (Slots and > Globals) is: For what is is good? > > Here is one example… in early stage but working. > > Imagine you want to “hook into” instance variable access. It can be done > with e.g. bytecode manipulation, or > on the AST level. But that is far from nice. > > With the new first class variables, there is now a fun way to do it: > MetaLinks. > > Make a class TT with an instance var “t” and add an accessor. > > Now we can define a MetaLink: it describes a call to a meta object that we > wan to do before, after or instead > of what our variable normally does. (default is #before): > > | link | > link := MetaLink new > metaObject: Halt; > selector: #now. > > This link says: “do a Halt now before where I will get installed”. > > To install the link, just get the Slot meta object and set it using #link: > > (TT slotNamed: #t) link: link. > > This sets the link by replacing the Slot with a LinkWrapper Slot, and then > recompiles all using methods. > > Thus evaluating: > > TT new t > > will get you a #halt. > > Lots of things are not yet implemented (multiple links, uninstall, > arguments,…) > but it starts to show how simple one can do quite powerful things. > > Marcus > > > > -- www.tudorgirba.com "Every thing has its own flow"
