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"

Types declared here follow the same type system as [types] (see Schema Additions) -- you can use built-in types, references to custom types defined in [types], and nullable shorthand.

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 a runtime error. The emit is rejected, a warning is recorded, and execution continues.

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 a runtime error. This prefix prevents collisions between extensions and with script-author $$var entries.

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