Breakpoints

A breakpoint is an an intentional pausing place in a program for debugging purpose. It is a means of getting information about a program during its execution. During the interruption, you can check whether the program is functioning as expected. In Smojo, we use the word

BP

to place a breakpoint in the code.

	: addition
		bp
		+ bp cr
		"The sum is " . . cr bp
	;

	5 2 addition

	--breakpoint: ADDITION[1] -- 
	<2> 5 2 

	--breakpoint: ADDITION[2] -- 
	<1> 7 

	The sum is  7 

	--breakpoint: ADDITION[3] -- 
	<0> 
	ok

Quiz

Question 1

Run the

ADDITION

program. Can you explain what happens at the three different breakpoints?

When

bp

is run, the state of the stack at that time is shown. At the first brakpoint,

and

are on the stack. At the second breakpoint, i.e., after

, the two numbers are consumed and their sum

is pushed onto the stack. At the third breakpoint, the number

is popped and printed so there is nothing on the stack.

Next: Conditionals I