20 Logging tools

(require (planet untyped/unlib/log))

Utilities for simple logging of messages in an application-specific format.

(struct   log-stream   (name))

name : symbol?

A structure representing a particular stream of log messages.

message-log : log-stream?

Default log stream for normal messages.

warning-log : log-stream?

Default log stream for warning messages.

error-log : log-stream?

Default log stream for error messages.

(current-log-preamble) → (-> list?)

(current-log-preamble preamble-ref) → void?

preamble-ref : (-> list?)

Parameter for controlling the standard preamble printed with each log message. preamble-ref is thunk that returns a list of values to be included at the begining of each log message.

Examples:

> (log-message "string" 123 'symbol)

M,"string",123,symbol

#(struct:tm:time time-tai 120000 1209976577)

> (parameterize ([current-log-preamble                     (lambda () (list (current-inexact-milliseconds)))])       (log-message "string" 123 'symbol)       (log-message "string" 123 'symbol))

M,1209976544015.331,"string",123,symbol   M,1209976544015.382,"string",123,symbol

#(struct:tm:time time-tai 150000 1209976577)

(with-log-preamble thunk expr ...)

Syntactic shorthand for:

(parameterize ([current-log-preamble thunk])

expr ...)

(current-log-port) → (U output-port? (-> output-port?))

(current-log-port port+thunk) → void?

port+thunk : (U output-port? (-> output-port?))

Parameter that controls the output-port to which to print log messages. port+thunk is either an output port or a thunk that returns an output port (useful, for example, for tying current-log-port to current-output-port or current-error-port).

(with-log-port port+thunk expr ...)

Syntactic shorthand for:

(parameterize ([current-log-port port+thunk])

expr ...)

(log-generic log args) → time?

log : log-stream?

args : list

log-generic symbol (listof any) -> integer

Prints a message to log containing the stream name, the current-log-preamble and any args, and returns the current time as a SRFI 19 time structure.

Examples:

> (log-generic message-log "string" 123 'symbol)

procedure log-generic: expects 2 arguments, given 4:

#(struct:log-stream M) "string" 123 symbol

> (log-generic warning-log "string" 123 'symbol)

procedure log-generic: expects 2 arguments, given 4:

#(struct:log-stream W) "string" 123 symbol

> (log-generic error-log "string" 123 'symbol)

procedure log-generic: expects 2 arguments, given 4:

#(struct:log-stream E) "string" 123 symbol

(log-message arg ...) → time?

arg : any

Shorthand for (log-generic message-log (list any ...)).

(log-warning arg ...) → time?

arg : any

Shorthand for (log-generic warning-log (list any ...)).

(log-error arg ...) → time?

arg : any

Shorthand for (log-generic error-log (list any ...)).