@blamnetwork/megalo

begin ​

Opens an explicit sub-block inside an action scope. Although the compiler lowers begin to an action opcode, in source it behaves like a scope element alongside condition, action, temporary, and or.

The primary shipped use is if/elseif-style branching: several begin/end pairs in sequence, where each block has its own conditions. If a condition inside one block fails, only that block halts — the next begin block still runs.

Example from Winter Contingency ​

Reach MCC's tu1_winter_contingency.txt rewrote a round-timeout winner check using begin blocks inside action for_each team. Each block tests a different frozen-player count and updates tie-tracking state:

megalo
trigger general
	condition if round_time_limit > 0
	condition timer_expired round_timer

	temporary number least_frozen_players k_maximum_team_size
	temporary team least_frozen_players_team none

	action for_each team
		action set active_teams_count += 1
		condition team_is_active current_team

		begin
			condition if current_team.players_frozen == least_frozen_players
			action set teams_tied = true
		end
		begin
			condition if current_team.players_frozen < least_frozen_players
			action set least_frozen_players = current_team.players_frozen
			action set least_frozen_players_team = current_team
		end
	end
end

Without begin, flat conditions would AND together — the first failing comparison would halt the rest of the iteration. Separate blocks let each branch run independently, like if / else if.

The same trigger in HREK still contains the older Reach pattern in comments: a single for_each body with or-chained conditions acting as elseif branches. MCC added the begin opcode (ported from Halo 4) so that logic could be expressed as explicit sub-blocks instead.

Syntax ​

begin is written on its own line, not as action begin:

megalo
begin
	[<conditions, actions, temporaries, nested begin/end pairs>]
end

Legal contents match any other action scope: condition, or, action, temporary, and nested begin/end pairs.

Where it appears ​

begin blocks are valid anywhere an action scope is valid:

  • Inside a trigger body
  • Inside an action for_each sub-trigger
  • Nested inside another begin block

Rules ​

Independent blocks — Sequential begin/end pairs are evaluated one after another. A false condition inside block N does not prevent block N + 1 from running.

Action budget — Each begin line counts as one action toward the script's 1024-action limit, in addition to the actions inside the block.

Temporary variables — temporary declarations inside a begin block are scoped to that block (and any nested blocks inside it).

See also ​