Hans Georg Schaathun wrote:
Is transmission by name the same as call by object?
No, it's not. With call-by-name, the caller passes a small function (known as a "thunk") that calculates the address of the parameter. Every time the callee needs to refer to the parameter, it evaluates this function. This allows some neat tricks, but it's massive overkill for most uses. In later languages, the functionality of call-by-name has been replaced by the ability to explicitly pass functions as parameters.
Anyway, I have never seen anyone counting more than three ways of doing this ...
There are other possibilities, such as value-result, where a local copy is made and its final value is copied back before returning. I think Fortran is defined in such a way that this is an acceptable way of implementing parameter passing. It's also the only way of getting anything akin to by-reference over an RPC connection. But for most situations, by-value and by-reference cover anything you might want to do. And if you have a dynamic data model like Python, you don't even need by-reference. -- Greg -- http://mail.python.org/mailman/listinfo/python-list
