Am 31.07.2018 um 06:57 schrieb Richard O'Keefe <raoknz@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 Uhn��k <i.uhnak@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