7.3 Preprocessor commands

A preprocessor command is a command that Hollywood processes before actually running your script. In Hollywood they are mainly used to preload data before the script is started. For example, if your script requires the files mainmenu.png, gamescreen.png and music.mod in any case, you could simply preload them by using the following code:

 
@BGPIC 1, "mainmenu.png"
@BGPIC 2, "gamescreen.png"
@MUSIC 1, "music.mod"

Hollywood will then load all those files before actually running your script. All files loaded via preprocessor commands are immediately ready for use when your script starts. Most of the LoadXXX() commands have their preprocessor command equivalent in Hollywood. For instance, the preprocessor equivalent of LoadBrush() is @BRUSH, the equivalent of LoadBGPic() is @BGPIC and so on.

Preprocessor commands are always prefixed by an at character (@). You should also write them in capital letters so that they can be distinguished better from normal commands. Preprocessor commands can be placed anywhere in the script, but for readability reasons it is suggested to put them at the beginning of your script.

An elementary preprocessor command is the @VERSION command. You should use it as the first thing in each of your scripts! @VERSION checks if the Hollywood version used is sufficient for running the script. Otherwise, Hollywood will abort.

Most preprocessor commands take several arguments which are separated by commas just like with normal commands. You can also use expressions in the preprocessor commands. For instance, the following declaration would be uncommon but perfectly valid:

 
@BRUSH 5+5, "MyBrush.png"

This would load MyBrush.png as brush number 10. What you cannot do, however, is using variables in your expressions. When Hollywood parses the preprocessor commands, it does not know anything about variable states because the script has not been started yet. Thus, all expressions you use must be constant.

Another advantage of the preprocessor commands is that all files specified here will be automatically linked into the executable when you compile your script. This behaviour can be changed by using the Link tag that is accepted by all preprocessor commands that work with files. This tag tells the Hollywood linker whether or not the file of that preprocessor command should be linked into the executable or applet when you compile a script. The Link tag always defaults to True which means that by default all files loaded through preprocessor commands will be linked to your executable or applet. If you do not want certain files to be linked, for example because they are too large, you have to specify this explicitly in the corresponding preprocessor commands.

The following preprocessor commands are available:

 
@ANIM            Preload an animation
@APPAUTHOR       Declare application author
@APPCOPYRIGHT    Declare application copyright
@APPDESCRIPTION  Declare application description
@APPICON         Declare application icon
@APPIDENTIFIER   Declare application identifier
@APPTITLE        Declare application title
@APPVERSION      Declare application version
@BACKFILL        Choose a backfill for your script
@BGPIC           Preload a background picture
@BRUSH           Preload a brush
@DIRECTORY       Link whole directory into applet or executable
@DISPLAY         Configure display settings
@ELSE            Block to enter if all conditions failed
@ELSEIF          Test for another condition
@ENDIF           Declare end of conditional block
@ERROR           Abort compilation with an error message
@FILE            Open a file
@FONT            Preload a font
@ICON            Preload an icon
@IF              Test for condition
@INCLUDE         Include code from another file
@LINKER          Pass options to the linker
@MENU            Create a menu strip
@MUSIC           Preload a music file
@OPTIONS         Configure miscellaneous options
@REQUIRE         Declare a plugin dependency
@SAMPLE          Preload a sample
@SCREEN          Configure screen mode for your script
@SPRITE          Preload a sprite
@VERSION         Define which Hollywood version your script requires
@VIDEO           Preload a video
@WARNING         Send warning message to debug device


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