Compiler directives

2017-08-16T23:29:02Z

216.156.220.117: /* Unreal Engine 3 */

'''Compiler directives''' are lines in [[UnrealScript]] source files that affect compiler behavior and have no meaning at runtime. They are not really used anymore in [[Unreal Engine 3]], which comes with a powerful [[preprocessor]] instead.

Directives are parsed during the compile process, not before that. This means they cannot be used in [[defaultproperties]] or [[cpptext]] sections. In fact, any directives in cpptext blocks will end up in exported header files for preprocessing by the C++ compiler.

==Syntax==
Compiler directives must be placed on a separate line. The syntax is as follows:
'''#'''''directivename'' ''parameters''
There must not be anything else before the '''#''' on that line and there shouldn't be anything after the directive name and parameters, except maybe a line comment. Directive names are case-insensitive, like any other part of UnrealScript syntax.

==Unreal Engine 1/2==
===call===
Similar to the "exec" console command in the editor and the game. Loads a list of console commands from a text file and executes them.

See [[exec commands]] for a useful selection of commands.

===error===
Immediately stops compiling with the message: "#Error directive encountered"

Note that there is no built-in conditional compiling, so using this directive may be quite pointless without an external preprocessor tool like [[UCPP]].

===exec===
The most-used directive and probably the only one most UnrealScript programmers ever need to use. The '''#exec''' directive executes an editor console command in the context of the compiler.

See [[exec commands]] for a useful selection of commands.

==Unreal Engine 2==

===include===
Loads a text file and replaces the #include line with its content.

There are several things to watch out for when using this directive:
* Line numbers reported in errors and warnings after the #include line will reflect the source text with the included content, so they no longer match the original source line numbers.
* If the included file contains a [[defaultproperties]] block, it is not included directly. Instead, its content is inserted into the class's defaultproperties block.

==Unreal Engine 3==
The only known directive in Unreal Engine 3 is '''#linenumber''', which is inserted by the preprocessor after an '''`include''' marco to make sure the compiler reports the line numbers the user expects.

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Compiler directives