Function Call and Return

It’s often helpful to know what a function’s parameters and corresponding return values were, and it can be annoying to manually print them out. No matter. Show has two decorators to make this easy:

def g(a):
    b = 3
    a += b
    return a



g(a=4) -> 7

The first line indicates the function being called. Additional debugging or program output may follow it. The second line here is displayed when the function returns. It reminds us what the parameters were, and then shows what return value resulted. If you like, you can specify the styling of these calls, e.g. with @show.inout(style='red').

While printing both the call entry and exit is often helpful, especially if many lines of output (or potential program crashes) may intervene. But in cases where a more compact, “only the results, please” print is desired, show takes a parameter that will show only function returns: @show.inout(only="out"). Function calls sans returns will be show if only='in'.

You may find it useful that inout is an individually-styleable method. To highlight function entry and exit points, try:



The @show.retval decorator has been deprecated, and will soon be removed. Please shift to @show.inout variants instead.