add if to borrowed ptr tutorial

This commit is contained in:
David Forsythe 2013-01-31 09:10:15 -08:00
parent 42b462e076
commit 72454f401e

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@ -50,7 +50,7 @@ Suppose we wanted to write a procedure that computed the distance between any
two points, no matter where they were stored. For example, we might like to
compute the distance between `on_the_stack` and `shared_box`, or between
`shared_box` and `unique_box`. One option is to define a function that takes
two arguments of type `Point`—that is, it takes the points by value. But we
two arguments of type `Point`—that is, it takes the points by value. But if we
define it this way, calling the function will cause the points to be
copied. For points, this is probably not so bad, but often copies are
expensive. Worse, if the data type contains mutable fields, copying can change