msg {tryr}

Write Logging Information to STDOUT or STDERR

Description

A simple logging utility that writes the log message to STDOUT or STDERR in plain text, JSON, or comma separated format.

Usage

msg(title = "", message = "", level = "INFO", format = NULL, digits = NULL)

x %+% y

Arguments

title

Character, the title of the logging message.

message

Character, a more detailed logging message.

level

Log level; one of "ALL", "TRACE", "DEBUG", "INFO", "SUCCESS", "WARN", "ERROR", "FATAL", "OFF" (case insensitive).

format

Log format: "PLAIN" (default), "JSON", "CSV" (case insensitive).

digits

Integer of length 1, digits for seconds (default 3L meaning milliseconds).

x, y

Strings to combine.

Details

The TRYR_ERR_LEVEL environment variable determines where the log message is written. If the log level is at least the one or above the TRYR_ERR_LEVEL value (or "WARN" when it is unset or null) the message is written to STDERR, otherwise it is written to STDOUT.

The log message is only written when the log level is at least the one or higher than specified by the TRYR_LOG_LEVEL environment variables; or "INFO" when the variable is unset or null.

The log format can be plain text, JSON, or comma separated text. When the log format is NULL the TRYR_LOG_FORMAT environment variables is checked. If it is unset or null, the format is considered plain text.

The logging message will be formed by combining the title and the message parts. The log info also contains the process ID, a timestamp (using Sys.time()), and the log level. The timestamp prints out fractional seconds according to digits. When digits is NULL it checks the TRYR_LOG_DIGITS environment variables and uses that value. The default is 3 when TRYR_LOG_DIGITS unset or null.

Besides the usual log levels, there is an extra one "SUCCESS" that is used to signal successful HTTP response codes (2xx).

Value

msg invisibly returns logical indicating if the log message was written (TRUE) or not (FALSE). A side effect is a log message to STDOUT or STDERR.

The ⁠%+%⁠ special pastes the right and left hand side together into s single string.

See Also

paste0(), sprintf()

Examples

n <- 5
"Sample " %+% "size " %+% "n = " %+% n %+% "."

msg("Success", "We did it!")
msg("Success", "We did it!", "SUCCESS")
msg("Error", "Oh no! n cannot be " %+% n, "ERROR")

msg("Success", "We did it!", "SUCCESS", format = "JSON")
msg("Success", "We did it!", format = "JSON")
msg("Error", "Oh no ...", "ERROR", format = "JSON")

msg("Success", "We did it!", digits = 0)
msg("Success", "We did it!", digits = 6)