Result Additions¶

Extensions declare what they contribute to the run result under the [result] section of the .laceext file. This serves two purposes:

The validator can type-check emit statements in rules against the declared structure.
Downstream tooling (backends, schema validators) knows what shape to expect from extensions.

Declaring result actions¶

Result action arrays are declared under [result.actions.<key>]:

[result.actions.notifications]
type = "array<notification_event>"

This declares that the extension will emit entries into result.actions.notifications. Each entry must conform to the notification_event type.

Declaring result types¶

Custom types used by result actions are declared under [result.types]:

[result.types.notification_event.fields]
callIndex      = "int"
conditionIndex = "int"
trigger         = "string"
scope           = "string?"
notification    = "notification_val"

A result type is a field record only: a fields table mapping each field name to a type name (no one_of or aliases -- those belong in the top-level [types] section). Field types use the same type system as [types] (see Schema Additions) -- built-in types, custom types defined in [types] (like notification_val above), and the nullable shorthand string?.

Full example¶

From laceNotifications.laceext:

# Declare the action array
[result.actions.notifications]
type = "array<notification_event>"

# Define the entry type
[result.types.notification_event.fields]
callIndex      = "int"
conditionIndex = "int"
trigger         = "string"
scope           = "string?"
notification    = "notification_val"

Rules then emit to this array:

emit result.actions.notifications <- {
  callIndex:      call.index,
  conditionIndex: -1,
  trigger:         "expect",
  scope:           scope.name,
  notification:    $notif
}

Emit targets¶

The emit statement can target two kinds of paths:

Target	Type	Behaviour
`result.actions.<key>`	array	Appends an object to the array. The array is initialised to `[]` if not yet present.
`result.runVars`	object	Merges a key-value pair into the `runVars` map. The key must be prefixed with the extension name.

Attempting to emit to any other path (e.g. result.calls, result.outcome) is rejected: the emit is dropped, a warning (EXT_EMIT_FORBIDDEN_TARGET) is recorded in the call's warnings array, and execution continues. Core result fields (calls, outcome, startedAt, endedAt, ...) are never writable.

Namespace rules for runVars¶

All keys emitted to result.runVars must be prefixed with the extension name followed by a dot:

emit result.runVars <- {
  "laceBaseline.stats": $new_stats
}

An emit where the key does not start with {extension_name}. is rejected the same way -- the emit is dropped and a warning (EXT_RUN_VAR_NAMESPACE) is recorded. This prefix prevents collisions between extensions and with script-author $$var entries (which are always bare identifiers).

See Variables & Config for more on reading and writing extension variables.