On Nov 18, 2:21 am, Antoon Pardon <[EMAIL PROTECTED]> wrote: > On 2008-11-12, greg <[EMAIL PROTECTED]> wrote: > > > Here is the definition of call-by-value from the > > "Revised Report on the Algorithmic Language Algol 60" > ><http://www.masswerk.at/algol60/report.htm>: > > > 4.7.3.1. Value assignment (call by value). All formal parameters quoted in > > the > > value part of the procedure declaration heading are assigned the values (cf. > > section 2.8. Values and types) of the corresponding actual parameters, these > > assignments being considers as being performed explicitly before entering > > the > > procedure body. The effect is as though an additional block embracing the > > procedure body were created in which these assignments were made to > > variables > > local to this fictitious block with types as given in the corresponding > > specifications (cf. section 5.4.5). > > > There you have it -- call by value is offially defined in > > terms of assignment. There is no mention in there of copying. > > Call by value is officially defined in terms of assignment in > a context where assignments means copying and in a definition > of a specifix language. > > You can't lift this part out of the definition of algol 60 > and say it applies equally well in languages with different > assignment semantics. > > If call by value is defined in terms of assignment regardless > of what the semantics of the assignment is then IMO call by > value is rather useless term and it would be better to talk > about call by copy in the case of C, to make sure one understands > the difference between what happens in C and what happens in > other languages that also have "call by assignment" but behave > very differently. > > -- > Antoon Pardon
I think Joe's argument was, C and Python can both be call-by-value, so long as Python variables are construed to be pointers. To him, pointers are easy to understand, even for novices, and the copy constructor for pointers is trivial. Otherwise, C and Algol have different definitions of call-by-value, and while Java might be Algol-call-by-value, Python is not C call-by- value. So, between C and Algol has majority and which has seniority claim to the term? -- http://mail.python.org/mailman/listinfo/python-list
