Compiler settings

Megalo source does not declare these options — they are compile-time switches that change how strictly the compiler interprets your script. The same .txt file can produce errors, warnings, or different variable allocation depending on which mode the editor uses.

HREK MegaloEdit always compiles in lenient mode (permissive defaults). Bungie's internal build farm probably used stricter settings. The switches live in ManagedMegalo.dll (ParsingHelper, MegaloCompiler); MegaloEdit wires them in but does not expose them in the UI.

MegaloEdit also exposes input and output directory settings (File → Settings). These paths control where the compiler looks for external files:

Setting	Used when resolving
Input directory	include and localized_include paths
Output directory	base references to compiled .mglo files

Include paths in source are relative to the input directory (and the including file). Base paths name a compiled variant in the output directory — by default maps/megalo under the HREK install when using MegaloEdit.exe. Compile the parent script first so its .mglo exists before building a derived script that references it. See Base files.

localized_include strictness

Controls whether a missing localized_include is optional or fatal.

Mode	Missing file behavior
Lenient (MegaloEdit)	Warning, include skipped — compile continues
Strict	Hard error, same as a missing plain include

When the file exists, behavior is identical in both modes.

MegaloEdit always uses lenient mode. See localized_include.

ManagedMegalo.dll: enforceLocalizedIncludes on ParsingHelper.

String literal strictness

Controls whether quoted literal strings in places that expect a string-table symbol are allowed.

Many elements require string table tokens — engine_data name slayer_title, not engine_data name "Slayer". In lenient mode, a literal still compiles but produces a warning:

You used a literal string '…'. Fix this before you submit. The build farm enforces localization.

In strict mode, the same literal is a hard error. Strict mode also blocks quoted strings anywhere the parser is enforcing localization.

MegaloEdit always uses lenient mode. Shipped Reach scripts use string-table symbols throughout.

ManagedMegalo.dll: enforceLocalization on ParsingHelper.

Temporary variable overflow

A temporary is a scratch variable declared inside a trigger or for_each block with the temporary keyword. It exists only for the duration of that block's execution — useful for holding getter results or intermediate values without declaring a permanent variables slot. See Variable model — Temporary variables.

Temporary allocation has changed across Megalo versions:

• Originally — when temporary was introduced, the compiler treated temporaries as global variables, allocating them directly from the global variable pool.
• Halo 4 — added a dedicated temporaries pool, effectively increasing how many scratch variables a trigger could use without consuming globals.
• Reach MCC — that separate pool was backported from Halo 4. Xbox 360 TU1 Reach still uses the original global-mapping behavior.

This overflow setting only applies to Megalo versions after Xbox 360 TU1 (Reach MCC and later). On TU1, temporaries already map to globals — there is no separate pool to overflow from.

On MCC Reach, each action scope has a fixed dedicated temporary pool per type. Per scope:

Type	Dedicated pool	Max overflow into globals
number	10	12
object	8	16
team	6	8
player	3	8

When overflow is enabled (MegaloEdit default), the compiler may spill excess temporaries into unused global variable slots of the same type once the dedicated pool is full, up to the overflow cap. When overflow is disabled, running out of temporary slots fails the compile.

This affects how much logic you can pack into a single scope — not syntax, but whether deeply nested temporary declarations are accepted. See 107 (MCC) — Limits and 107 — Limits for scope nesting and TU1 behavior.

ManagedMegalo.dll: TemporaryVariablesCanOverflowIntoUnusedGlobalVariables on MegaloCompiler.

See also Megalo versions (MCC vs TU1).

Summary

Setting	Lenient (MegaloEdit)	Strict	Language feature
Input directory	—	—	include, localized_include
Output directory	—	—	base (.mglo lookup)
Localized includes	Missing file → warning	Missing file → error	localized_include
String literals	Warning	Error	String-table symbols vs "quoted" text
Temporary overflow (MCC+)	Spill into free globals	Compile fails when pool full	temporary in triggers

See also

• Base files — derived scripts and .mglo lookup
• localized_include
• Syntax — Includes
• trigger — Action scope
• Variable model — Temporary variables
• Megalo versions — MCC vs Xbox 360 TU1