Introduction to Macro Branching

Introduction

When you write a macro, you'll frequently find yourelf wanting to either repeat an operation several times, or to choose from several options based on the outcome of a macro command. In game terms, you might want to make an damage roll several times in a row (say, one time for each enemy caught by a grenade blast), or you might want your macro to give you a damage roll if you hit, and say You missed! if you miss.

In programming jargon, those concepts are called looping (where you go through a process repeatedly, or "loop through it"), and branching (where your program - in this case, the macro - "branches" down different paths). The MapTool macro language has several roll options (and one function) to let you branch and/or loop your commands.

Finally, because there are a lot of times when you'll want to do several things at the same time when you branch or loop, there's a special roll option called code that tells MapTool to treat several macro commands as a single "unit" when you loop or branch. That may sound confusing, but you'll see what it all means shortly!

Assumptions

We're going to get to using these options pretty fast, so I assume you've read the Introduction to Macro Writing and have knowledge of how to create a new macro and use some very basic commands in it (like creating a variable or a dice roll).

There are a couple concepts that should be introduced first, since they're going to be a great way to illustrate some of the looping and branching concepts. Those are covered in the next section.

New Concept: String Lists and String Properties

RPGs have a lot of information that goes into playing them - there are stats, and skills, and dice rolls, and weapons, and equipment, and powers and magic and...well, you name it, and there's an RPG out there that covers it.

For basic things, it might make sense to create a token property for each piece of information. In fact, you can do this for every possible bit of information you want to record about a character - but already, I bet you're thinking "that's a lot of properties"). And it is!

Fortunately, there are other ways to store information in MapTool properties (and macro variables) that let you group information together. The two new information storing methods we'll use - which are properly referred to as data types - are string lists and string properties.

String Lists

A string list is, first, a string - that is, a collection of alphanumeric text that is treated as just text (that is, it's not a number, so you can't add it to another number; it's not a dice roll, so MapTool won't automatically roll it; it's just a string of characters).

Second, it is a list - a collection of single items, separated by some sort of separating character - the (you guessed it) separator (also called a delimiter). The separator marks the beginning and end of an individual item in a list. This is a long way of saying "a string list is a single value that is a list of things, like colors: blue, green, red, orange, mauve."

Formally - in macro code - a string list looks like:

[h:listOfColors = "blue, green, red, orange, mauve"]

In the example, you'll see that we've made a variable assignment, and given the variable listOfColors the values blue, green, red, orange, mauve. The whole thing is enclosed in double quotes, which tells MapTool that it's a string, and from its very format, MapTool knows that it's a string list.

A string list can contain anything - it could be a list of names, of numbers, of dice rolls - anything you might want to keep a list of.

However! It is important to remember that no matter what each item in a string list is, it is always treated as a string. So if MapTool reads a string list that looks like "1d6, 2d8, 1d20", it will not see the first item and see a command to roll 1 six-sided die; instead it will see the character "1", the character "d", and the character "6", all put together. They may look the same to us, but they don't look the same to MapTool - to turn that "1d6" into 1d6 so that MapTool will roll it, we need to use the eval() function to tell MapTool "evaluate that string as if it were a dice roll." You'll see some examples of eval() later on.

String Properties

String properties are very similar to string lists - they are strings with special formatting, and they contain a collection of items. However, string properties have additional features that make them very useful for storing information in a different way.

The essence of a string property is the the key - value pairing. Basically, for each item in the string property, there is a key that is paired with a value. For instance, if you have a weapon with the following details:

Weapon Name: Broadsword
Weapon Damage Dice: 1d8
Weapon Damage Type: Slashing
Weapon Category: Versatile

You have a series of key - value pairs: the key "Weapon Name" is paired with the value "Broadsword," the key "Weapon Damage Dice" is paired with the value "1d8," and so on. A string property is simply a "formal" way to set up this kind of pairing in a single variable. The string property for the above weapon might read:

[h:weapon1 = "name=Broadsword; damageDice=1d8; damageType=Slashing; category=Versatile;"]

In that string property, the word to the left of the equal sign is the key, and the word to the right is the value. The semicolon is the separator or delimiter. MapTool has special functions to retrieve and change the values within a string property, which you'll see in use later.

New Concept: The CODE Option

Normally, in any branching or looping technique, MapTool lets you do one thing - that is, one command. So if you had a statement that said "if a condition is true, do something cool," then "something cool" can only be one single thing - you might roll some dice, or assign a variable, or print out some text to the chat window. However, you couldn't roll some dice, assign a variable, assign another variable, do some math, and then print out something all in that statement. That's too many operations.

If you could only do one thing when you branch or loop, macros would be very limited - so the macro language supports a special roll option called CODE, which indicates to MapTool that you want to do several things at once, but have them all happen as a single "branch" or "loop." You would group these several commands inside a pair of curly braces ( { } ).

The examples below will use the CODE option, so you can see how it works.

New Concept: Comparison and Logical Operators

In macro writing, you're going to want to compare values together a lot - is my dice roll greater than 20? Are my hit points less than 0? Does that weapon name equal "Warhammer?" All of these are handled via comparison operators and logical operators.

Comparison Operator is programming jargon for the symbols we use to have MapTool compare two values to each other in certain ways (an operator is a symbol that performs an operation - for instance, the + symbol is an operator that adds things together).

A Logical Operator is a symbol you use to instruct MapTool in what order to consider comparisons, and how to group comparisons together. The comparison and logical operators are described below:

In the examples below, the if() function is used to illustrate the examples. It's described in more detail later, but the basic "format" of the if() function is this:

if(comparison, value_if_true, value_if_false)

Comparison is where you do your actual comparison (greater than, less than, etc.)
Value_if_true is where you put the output or value if the comparison is true
Value_if_false is, obviously, where you put the output or value if the comparison is false

Comparisons

The symbols below are the comparison operators. Remember that you must always think of these comparisons from the reference point of the value on the left side. So, in the comparison value1 > value2, you read it based on the left side: "is value1 greater than value2. This is the rule for comparisons in MapTool - the left side of the operator is the "point of view."

==: "is equal to;" this is the operator you use to see if one value is equal to another. Be careful - it has two equals signs in a row (remember, one equal sign is already reserved for assigning values to variable). An example of this comparison would look like {{{1}}}
>: "is greater than; use this to see if the value on the left side is greater than the value on the right. For example: {{code|[if(roll > 17, "Hit!", "Miss")]. You can put a number on the left side, like [if(17 > roll, "Miss", "Hit!")] (note that it basically reverses the first example, so you need to switch the true and false outputs).
>=: "is greater than or equal to"; use this to see if the value on the left side is greater than or equal to the value on the right. For example: {{{1}}}
<: "is less than"; use this to see if the value on the left side is less than the value on the right. For example, [if(roll < 19, "Miss", "Hit!")]}
<=: "is less than or equal to"; use this to see if the value on the left side is less than or equal to the value on the right. For example: {{{1}}}
!=: "is not equal to"; use this to compare whether the value on the left side is not equal to the value on the right. Note that this operator doesn't care what the values actually are, only that they are not equal. For example, {{{1}}}

Logical

The symbols below are the logical operators. You use this to group comparisons together (you only need these if you need to make multiple comparisons at the same time). These go between individual comparisons (these don't replace the comparison operators above!).

&&: "and"; use this if you want to make sure that two or more comparisons are all true. For example: [if(roll > 1 && roll < 20, "Hit", "Miss")] requires both comparisons to be true, for the whole comparison group to be true. In other words, the roll must be greater than 1 and less than 20 in order for it to be a hit. If both of those aren't true, the output is Miss.
- Remember: if you use &&, every part of the comparison statement must be true for the whole comparison to be true!
||: "or"; use this if you want or need only one out of multiple comparisons to be true, in order for the whole thing to be true. For example, . In the example, if either condition is true (that is, if enemyHealth is "dead" or "dying") the entire comparison group is true. Only if neither comparison is true does the whole thing become false.
- Remember: use || if you only need one out of several comparisons to be true

IF: Comparing Values

One of the most elementary ways to branch any code is the use of the idea of if. That is, if some comparison is true, then do something else. You would use the if concept to say "If my attack hits, then show the damage result!"

MapTool's macro language has two kinds of if - a function (a function is a pre-defined set of instructions that you can "call" by referring to it by name), and a roll option (a roll option is a "switch" or "toggle" that tells MapTool how to handle a command.

if() Function

The Template:function function is called simply by writing if() and putting the thing you want compared, what to do if the comparison is true, and what to do if the comparison is false, all inside the parentheses. The general format is:

if(comparison, value_if_true, value_if_false)

An actual example would look like:

[if(attackHits == "yes", "You hit!", "You missed")]

In that single line, we've said:

Check the variable attackHits to see if it has the value "yes"
If it has the value "yes", then print You hit! to chat, or
If it does not have the value "yes", then prin You missed to chat

The value_if_true and value_if_false parts of the if() statement can be text, dice roll commands (like 1d6 or 1d20), or variables. What they cannot be is variable assignments - that is, you can't write an if() statement like this:

[if(attackHits=="yes", output = "You Hit!", output = "You missed")]

It may seem like a good idea, but it won't work - MapTool will give what's known as a null pointer exception, and the macro will fail. However, there is a trick to get around that: since if() is a function, and all functions - when they run - produce a value, you can assign the result of it to a variable! You would do it like this:

[output = if(attackHits=="yes", "You Hit!", "You missed")]

When you do it that way, MapTool will:

First, decide what the result of the if() is, and
Second, assign that result to the variable output, which you can then use like any variable