I think you meant z = x y, Owen. In the TUTOR language of the PLATO computer-based education system (see links on my home page, http://www4.ncsu.edu/~basherwo), I implemented a function called "compute" for evaluating algebraic student input in which xy (or x y) was treated as x*y. The method relied on the fact that in typical algebraic usage in educational settings variables have short names. The symbol-table lookup searched for the longest name, so that if x, y, and xy were all defined "xy" was taken to mean a reference to the variable xy. But if only x and y were defined, "xy" was taken to mean x*y.
However, for clarity and lack of ambiguity ordinary calculations in the TUTOR language did not permit implied multiplication. If you meant x*y you had to express it as x*y. Another interesting aspect of the compute function was that it compiled the expression to machine code and stored this code in a buffer where it could be reused, thereby permitting fast looping execution of user-input statements. Bruce On Sun, Apr 1, 2012 at 12:02 AM, Owen Densmore <[email protected]> wrote: > Bjarne Stroustrup, creator of C++, posed this interesting use of > overloading: > > http://www2.research.att.com/~bs/whitespace98.pdf > > > The idea was somewhat forced upon him by ATT Labs mathematicians and > physicists who wanted: > > int x,y,z; > z=xy > > to function as in standard math notation as set z to x times y. > > I believe the notion failed to achieve popularity due to lexical scoping of > the language, where variables might lie in entirely different bodies of > source code. Closures were, of course considered as a way to define the > allowed scope for variables, but C++ had not implemented them. > > -- Owen > > > > > ============================================================ > FRIAM Applied Complexity Group listserv > Meets Fridays 9a-11:30 at cafe at St. John's College > lectures, archives, unsubscribe, maps at http://www.friam.org ============================================================ FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College lectures, archives, unsubscribe, maps at http://www.friam.org
