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Create a hook

Source: R/hooks.R
HookMatcher.Rd

HookMatcher() pairs a callback with a hook event and, optionally, a tool-name pattern. Add it to an agent with agent$add_hook(). The object is read-only; read its fields with @ or S7::prop().

Usage

HookMatcher(event, callback, pattern = NULL, timeout = 0)

Arguments

event

One of HookEvent.

callback

A function taking the arguments listed for event in HookEvent, or .... HookMatcher() errors if the arguments don't fit.

pattern

Optional regular expression matched against the tool name. A hook with a pattern only fires for events that have a tool name.

timeout

Time limit for the callback, in seconds. The default, 0, runs the callback in your R session with no limit. A positive value runs it in a fresh R process with callr::r(). That process can't see your global variables or attached packages (call functions as pkg::fn()), and its printed output and other side effects stay there.

Value

A HookMatcher object.

See also

hook_matches()

Examples

hook <- HookMatcher(
  "PreToolUse",
  callback = function(tool_name, tool_input, context) {
    HookResultPreToolUse(permission = "deny", reason = "Read only")
  },
  pattern = "^write_"
)
hook_matches(hook, "write_file")
#> [1] TRUE
S7::prop(hook, "event")
#> [1] "PreToolUse"