Norbert Hartl wrote: > the biggest problem with a copy approach is that all identity checks fail with the copied objects
The scheme I proposed *hides* the (shallow) copies. The only thing ever done with them is to copy their contents back into the original objects. There are therefore no "identity checks ... with the copied objects" for anyone to care about. On 31 July 2018 at 18:47, Norbert Hartl <norb...@hartl.name> wrote: > > > Am 31.07.2018 um 06:57 schrieb Richard O'Keefe <rao...@gmail.com>: > > Basically, what you are talking about is Software Transactional Memory. > According to https://en.wikipedia.org/wiki/Software_transactional_ > memory#Smalltalk > there *is* STM support for Pharo at > http://source.lukas-renggli.ch/transactional/ > although the last version there is from 2012, and there have been major > changes to Pharo > since then, so it probably doesn't work any longer. > > You could probably make a TransactionalObject class with a > 'lastTransaction' > instance variable, and a noteChange method that checks if lastTransaction > == > Transaction current, and if not, pushes self -> self shallowCopy onto a > stack > inside Transaction and sets lastTransaction to Transaction current. Then > to > roll back a transaction, peel back original -> backup records from the > stack > and do original copyFrom: backup for each of them. > > Please don't ask me to think about combining this with concurrency. > > You could delegate the transaction list and other objects to a process > specific variable. But the biggest problem with a copy approach is that all > identity checks fail with the copied objects > > Norbert > > On 31 July 2018 at 01:16, Peter Uhnák <i.uh...@gmail.com> wrote: > >> Hi, >> >> is there some library or approach how to do transactions in pharo? >> And I don't mean database transactions, but directly in memory on Pharo >> objects... e.g. >> >> p := Person new. >> >> transaction do: [ >> p name: 'Nobody'. >> p age: 70. >> ] on: Error do: [ >> transaction rollback. >> ]. >> >> self assert: p name equals: 'Nobody'. >> self assert: p age equals: 70. >> >> transaction do: [ >> p name: 'Somebody'. >> p age: 1 / 0. >> ] on: Error do: [ >> transaction rollback. >> ]. >> >> self assert: p name equals: 'Nobody'. >> self assert: p age equals: 70. >> >> Any pointers appreciated. >> >> Thanks, >> Peter >> > >
