Passing arguments
Most function calls in Julia can involve a set of one or more arguments and, in addition, it is possible to designate an argument as being optional and provide a default value.
It is useful if the number of arguments are of varying length and we may also wish to specify an argument by name rather than by its position in the list.
How this is done will be discussed now.
Default and optional arguments
In the examples so far, all arguments to the function were required, and the function call will produce unless all are provided. If the argument type is not given, a type of Any
is passed. It is up to the body or the function to treat an Any
argument for all the cases that might occur, or trap the error and raise an exception.
For example, multiplying two integers results in an integer and two reals results in a real. If we multiply an integer by a real, we get a real number. The integer is said to be promoted to a real. Similarly, when a real is multiplied...