Translations of this page:

008 stats

step008

more detailed stat values

attack, defense and damage

At the current version of Goblin Dice Duel, only the random.randint() functions explain if a goblin get hit on the head and how much it hurts. Morst Role-Playing-Games use not only the concept of hitpoints but also various combat stats, like values for attack, defense and damage.

The easy part is to introduce the new variables in python:

hitpointsStinky = 22
attackStinky = 6
defenseStinky = 9
hitpointsGrunty = 43
attackGrunty = 5
defenseGrunty = 3

comparing stats

Before going wild with some combat mechanics, let me first introduce a function to make a pretty compare table of those combat stats. Actually, a function that calls another function. And a reminder of the if elif else structure as well. And something about local scope of variables. And return values. In short, let's practice a bit the things you learned so far. You best type this whole example in your python editor:

source code

click reload on your browser if you see no source code here or visit Github.com

online

Or you can try it out online (click on the graphic below):
click me

output

The output of this program is pretty….pretty:

          Stiny | vs. | Grunty 
 ---------------+-----+-----------
 hitpoints:  22 |  <  |  43
 attack:      6 |  >  |   5
 defense:     9 |  >  |   3

code discussion

sign function

Now make sure you understand all what is happening so far (use the online debugger above). Take a look at the first defined function with the name sign(). All what the sign() function needs as parameters are two things that python can compare. In our case those things will be integer stat values of Stinky and Grunty, but the sign() function could also compare Strings or other objects. The sign() function compare the two things passed as arguments and returns either a > sign, a > sign or an = sign. Note that each return value is of type string because of the quotes. Also note that a function always terminates after running into an return statement and python goes back to the point from where the function was called.

This leads to the question: Who calls the sign() function ?

Scan the whole code for sign( outside the function definition.

Most Editors support the Hot-Key CTRL + F to start a find function. Even your browser does.

Found it ? The sign() function is called three times, from inside the .format() command in the compareValues() function. The whole point of the compareValues() function is to make a pretty table to show the player whose stats are better. And instead coding the whole if-elif-else block three times into the compareValues() function i prefer to code (the sign() function) only once and call it three times.

Note that the caller of the sign() function makes good use of the sign() functions return value: it is directly used to create the compare table string. Remember: The caller of a function has to make use of return value of a function, or the return value …is of no use.

compareValues function

Take a look at the second function, the compareValue() funciton. As you can see this function need 6 (!) parameters and all it returns is a single text String. But a pretty one !

If you wonder how to create this vertival line, the “pipe” |: Depending on your keyboard layout, you must press another key to get it (german keyboard layouts need to press ALT GR and <. You may have a tool on your Computer named Charmap that helps you identify signs of your keyboard and remap them. In the worst case, use a ! instead of the pipe.

As you may have noticed i use no longer the print() function but instead i create and return a giant text string. A side effect is that i loose all those line endings that the print() function was taking care for me. So i have to code a new line sign, the \n everywhere in the code where i want a new line. (I love to do that at the start of each code line so that i can not forget it at the end of the code line). Inside a text string, something beginning with an backslash is often a Control_character or an Escape_sequence. See the python documentation for a list of useful Escape sequences.

The reason not to use print() instead of the text string lays in the future: I want to make this example work on webpages or in a Graphical_user_interface where print() does not work. Textstrings, on the other hand, will work and will be passed as arguments to some ultra-modern “make this visible with many colors” function.

calling the funciton(s)

Now to the last part of the previous code example, where the stat variables are defined and where the functions are called. It is here that the code actually begins. A def block of a function will not be computed by python until it is actually called. You must, however, define a function before you can call it, so that python knows where the called function is located.

Please take a look at the parameters of the functions. The compareValues() function is called with the parameters hitpointsStinky, attackStinky, defenseStinky etc but in the definition block of the function it takes hpA, attA, defA etc. as parameters. What happens here ?

Remember the local scope of functions. Each function has it's own scope, meaning it can create variables locally that already exist outside the function and use it for complete other purposes and values. The variables outside the function will not be affected or polluted (unless global variables. But i don't use them anyway). The only way of the world outside of a function to “communicate” with the function is to pass parameters while calling the function and (maybe) getting return values form the function. In-between, there is no interaction of the outside world with the function.

That means that the function does not need to care how it's parameters are named outside the function… the function can name the parameters anyhow, preferable so that it is short to type but good to undertand. Therefore, attA instead of attackStinky etc.

Also take some time to make sure that you understand the Program_flow correctly:

program flow

  1. the print() function calls the compareValues() function iwth 6 arguments
  2. the function compareValues() calls the function sign() with the values for both hitpoint stats as arguments and uses the return value
  3. the function compareValues() calls the function sign() with the values for both attack stats as arguments and uses the return value
  4. the function compareValues() calls the function sign() with the values for both defense stats as arguments and uses the return value
  5. the return value of the compareValues() function (a text string) is directly printed on the screen by the calling print() function

A last thing: the last line in the code example (the print() function) is so long that it makes scrolling necessary when looking at the source code. Because that is not comfortable, i split the (python) line into 2 (physical) lines. As long as such a split happens inside brackets, python is clever enough to figure out that both (physical) lines are in reality one giant (python) line.

step008

en/python/goblins/step008.txt · Last modified: 2014/01/09 11:07 (external edit)