More Branching Options

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INTERMEDIATE
THIS IS AN INTERMEDIATE ARTICLE

Introduction

This is a guide to the "advanced" macro branching option, [macro():].

Assumptions

This assumes you have an understanding of what a roll option is, and that you've read the preceding tutorials.

Also, don't forget to enable the Use ToolTips for Inline Rolls option in MapTool Preferences.

MACRO: Running Other Macros

One of the best practices when you write macros - especially when they become complex - is to keep them streamlined and lean, and only have them do what they need to do - for instance, if you have a macro that adds a skill to a token, it doesn't need to be the same macro that checks to see if an attack hits, or records damage taken. It just adds skills.

Writing macros this way - each macro doing something relatively small - is a good way to keep yourself organized and keep your macros clear (it also makes them easier to fix if something goes wrong!). What's more, it helps keep your memory use lower, so you don't get run into stack overflow errors or, more commonly, slow macros.

But if you do this, how can you make one macro run based on another one - surely, you don't want to have to hit each button every time something happens, right? Enter the [macro():] roll option.

What's It Do?

The [macro():] roll option is the way that you can have one macro - the calling macro - trigger another macro, which we call the called macro. The calling macro can send some information to the called macro, where that information will be handled and processed and probably changed, and then, if you like, the called macro can send some information back to the caller.

Why would I Use It?

Where this comes in handy is in three circumstances: first, when you have some operation that you're always doing, but you have several different ways that it might come up. Second, if you have a macro that everyone uses. The third, and more powerful use, is when you want to manipulate another token besides your own - then you frequently need to use called macros, because there are some things only a called macro can do!

Common Tasks from Multiple Pathways

Let's look at the first benefit: take, for example, a macro that applies damage to a token in accordance with the Sample Ruleset (in other words, it looks at a token's properties, and then deducts damage from the token's HitPoints property). How many ways can you think a token might get damaged?

1. It could get damaged by an attack from an enemy
2. It could get damaged by an attack from a friend (accidental or otherwise)
3. It could get damaged by falling
4. It could be damaged by a trap

All kinds of ways. Now, suppose you have three macros to handle damage. These macros are called Enemy Attack, Friendly Fire, and Environmental Damage. Each of these causes a token's HitPoints to be reduced, but each also has some special processing to determine just how much HP reduction takes place (it's not important what the special processing is at the moment).

So you have three macros, but each has a common element: they all in the end reduce the token's HitPoints. Consider a couple of alternatives - you can:

1. Write each macro separately, including the calculations to reduce HitPoints; or
2. Write a fourth macro, containing just the calculations to reduce HitPoints, and have the three damage handler macros call that fourth macro to handle the final calculations.

The advantages of the first option are that you only need to write three macros, and you're done. On the other hand, what if you realize you made a mistake in your damage macro? You then have to edit it in three places. In the second option, you only edit one copy of the damage macro.

Tasks Everyone Does

Building on the example above, if you have a whole bunch of macros that everyone uses (perhaps everyone needs to have a way to attack, to defend, and to take and heal damage), you can create a single set of macros that everyone simply calls, rather than duplicating every macro on every token, every time you need a new token on the map.

So, for example, you may want to build a "library" of macros to handle your game (whatever game it happens to be), and then create a single set of macros on your tokens that do nothing but call macros in the library.

You'll note that it doesn't mean you have fewer macros overall - every token still needs a set of macros to call on the library; however, it does mean that your actual complex macros (the ones that took you a long time to write) are all in one place, and you only need to alter one copy in order to fix an error. If you'd copied the entire macro set to every token, you'd have to fix every single token one at a time to fix any mistakes you made.

Manipulating Other Tokens and Trusted Macros

Generally, when a token runs a macro, or calls a macro, the macro assumes that all properties and variables it needs to use apply to the token running the macro. So if Bork the Brave calls a macro in a macro library, that library macro is going to assume that it needs to do its thing on Bork the Brave.

However, sometimes Bork the Brave does not want this - maybe Bork the Brave just whacked a troll with his sword, and wants the damage to be applied to the troll (and, by extension, most definitely does not want the damage applied to himself!). He's going to want a macro that will affect the troll's token, not his own.

As it turns out, however, there are some things (as mentioned before) that a regular old macro on a player token simply can't do. For instance, a macro on a player token can't go and determine what an NPC token's properties are. It's simply not permitted to access another token. I think you'll agree this is a good way to go - you may not want players being able to see property values on an NPC. Furthermore, a player token macro can't change values on another token. Nobody wants the players to be able to, for instance, reduce an enemy's armor value to zero just before making an attack.

But still, we want to be able to do some things to other tokens, right? In response to that, the concept of trusted macros was developed. Trusted macros are simply macros that can perform certain functions unavailable to other macros, such as the functions that manipulate token properties other than the ones on the token who called the macro.

How Do I Use It?

[macro():] is a roll option so, like other roll options you've seen, it is put at the beginning of a line and ends with a colon. The essential format of the [macro():] roll option is:

<source lang="mtmacro"> [MACRO("macroName@Lib:token"): macro_arguments] </syntaxhighlight>

In the above example, there are several parts:

• The opening and closing square brackets ([ ]), which surround all macro commands in MapTool
• The word "MACRO" (it does not have to be capitalized; that's done to keep it noticeable!), which is just the name of this particular roll option
• macroName: this is the name of the macro you wish to call
• @: this is used in the same sense as in an email address - it means "at"
• Lib:token: this is the Library Token that contains the macro you wish to call. Library tokens are a complex subject, but you can think of them as a single token that holds a "library" of macros that can be called by other tokens or call each other.
• macro_arguments: an argument is a programming term for information that you send to a function (or in this case, a macro) that you want the function to do something to. If you had a function that added two numbers together, the numbers you send to it would be the "arguments" to that function.

So in the command above, you've said "run the macro called macroName at the library token Lib:token, and send it macro_arguments to work on." The programming jargon for what you've just done is "calling a macro," or "creating a macro call."

The next section will have some actual examples to help you get a grasp of using [MACRO():].

Working with Arguments and Returns

In programming terms, a function is a set of commands that receives arguments (described briefly above), does some processing on those arguments, and then returns a value to the place from where it was called. The macro roll option is not technically a function but when it is used the process is mostly similar: it calls another macro (sending it arguments) and that other macro may - if you write the macro so that it does - return a value to the calling macro.

When you call a macro you can send it any variable, string, or number as an argument (in other words, you can replace macro_arguments with a variable, a string, or a number, which is sent to the called macro). For example, let us assume the following:

• There is a Library Token called "'Lib:MT which has a macro called Use Power.
• You have a token for Bork the Brave, which has a macro called Shield Bash. This is one of Bork's powers.
• You want to send the name of the power to Use Power, which will run the standard procedures to resolve the use of a power.

To have Bork's macro trigger the Use Power macro on Lib:MT, you would create a macro called "Shield Bash", which contained the following command:

<source lang="mtmacro"> [macro("Use Power@Lib:MT"): "Shield Bash"] </syntaxhighlight>

So, that's great. You've sent this information off to the macro Use Power. But...how does Use Power recognize what you sent it?

The Special Variable macro.args

Whenever you create a macro call and execute it, a special variable called macro.args is created. This variable is visible (that is, can be accessed, changed, or read) only by the macro being called, and it contains whatever you substituted in for macro_arguments. So, in our example above, macro.args is equal to "Shield Bash". So, for example, in the macro Use Power, you might have a line that says:

<source lang="mtmacro"> [h:powerName = macro.args] </syntaxhighlight>

What that line says is, "in this macro, take the value of macro.args, and assign it to the variable powerName." From then on out, the variable powerName will have the value "Shield Bash" (if we continue our example from above). Note that you don't have to do this - you can also just refer to macro.args wherever you need to.

The macro being called can then use this special variable macro.args like any other variable - it can read it, it can change it, it can add it to something - anything you would do with a variable. You could even ignore it!

Of course, if you've sent information in one direction - from the caller to the callee, so to speak - what if you need to send information the other way (in other words, return a value)?

The Special Variable macro.return

In the macro that is being called, you can do a lot of processing on the variable macro.args. You can output text to chat and update token properties, even. But you might also want the results of all that processing to be sent back to the calling macro - maybe you use it to create part of a string, and you need to send that piece back to be assembled into the final output you want to send to chat.

In that case, you can assign whatever value you want to send back to the variable macro.return, which will be sent back to the calling macro. Assume, then, that the macro Use Power creates a variable called powerResultText that needs to be sent back to Bork's macro Shield Bash before it finishes. To do this, somewhere at the end of Use Power, you'd add this line:

<source lang="mtmacro"> [h:macro.return = powerResultText] </syntaxhighlight>

You've said in that line that the special variable macro.return will be equal to whatever powerResultText is set to, and Shield Bash can then use the variable macro.return for further processing.

Side by Side Examples

The examples below are the two macros discussed above, side by side, to illustrate the use of macro calls and the macro.args and macro.return variables. Make sure to check out the Sample Ruleset if you're not familiar with some of the various game terms. Also, note that these are not complete macros that include all of the possible classes and powers in the game, but a sampling to illustrate the use of [MACRO():].

Shield Bash Macro

Use Power Macro

<source lang="mtmacro" line> [MACRO("Use Power@Lib:MT"): "Shield Bash"] [h:hitValue = macro.return] [h,if(hitValue == 1),CODE: { [damageRoll = floor((1d6+Strength)/2)] [special = "Roll 1d6. On a 4 or better, the foe is stunned for three rounds."] }; { [damageRoll = "None"] [special = "No special effect."] }] Damage: [r:damageRoll] Special: [r:special] </syntaxhighlight>

<source lang="mtmacro" line> [h:powerName = macro.args] [h,switch(powerName): case "Sword": attackBonus = 2; case "Bow": attackBonus = 0; case "Shield Bash": attackBonus = -1;] [h:attackRoll = 1d20 + Strength + attackBonus] [h,if(attackRoll >= 15),CODE: { [successText = "a success!"] [hit = 1] }; { [successText = "a failure."] [hit = 0] }] The [r:powerName] attack is [r:successText]. [h:macro.return=hit] </syntaxhighlight>

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