Finding the instance reference of an object

Steven D'Aprano steve at REMOVE-THIS-cybersource.com.au
Sun Oct 19 11:07:25 CEST 2008


On Fri, 17 Oct 2008 16:36:24 -0400, Steve Holden wrote:

> People here don't describe Python as different just because they *want*
> it to be different. Python acknowledges intellectual debts to many
> languages, none of which is exactly like it.

I understand that Python's object and calling semantics are exactly the 
same as Emerald (and likely other languages as well), and that both 
Emerald and Python are explicitly based on those of CLU, as described by 
by Barbara Liskov in 1979:

    "In particular it is not call by value because mutations 
     of arguments performed by the called routine will be 
     visible to the caller. And it is not call by reference 
     because access is not given to the variables of the 
     caller, but merely to certain objects."

http://www.lcs.mit.edu/publications/pubs/pdf/MIT-LCS-TR-225.pdf

quoted by Fredrik Lundh here:
http://mail.python.org/pipermail/python-list/2003-May/204379.html


"Call by object/sharing" isn't some new-fangled affectation invented by 
comp.lang.python dweebs to make Python seem edgy and different. It's a 
term that has been in use in highly respected Comp Sci circles for over 
thirty years. In case anybody doesn't recognise the name:

http://en.wikipedia.org/wiki/Barbara_Liskov


-- 
Steven



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