Copyright	(c) 2020-2021 Sam May
License	GPL-3.0-or-later
Maintainer	ag@eitilt.life
Stability	stable
Portability	non-portable (requires libcdio)
Safe Haskell	None
Language	Haskell2010

Foreign.Libcdio.Logging

Contents

Types
Message interaction
Management

Description

The underlying library is rather loud in its error and warning messages, potentially emitting a lot of impure terminal clutter even on some otherwise-pure functions. Very helpfully, it also provides a mechanism for integrating the logs with whatever framework is in place for the larger project; that mechanism can be leveraged to cache the logs in memory until specifically asked for, at which point they can be packaged into Haskell types. Some of the immediacy—and therefore user ability to match note to source—is unfortunately lost, but the apparent purity is worth it.

`logging.h`

Types

cdio_log_level_t -> LogLevel

Symbols

cdio_default_log_handler (removed; always handled through readLog)
cdio_assert -> putLog LogAssert
cdio_debug -> putLog LogDebug
cdio_error -> putLog LogError
cdio_info -> putLog LogInfo
cdio_log -> putLog
cdio_log_set_handler (removed; always handled through readLog)
cdio_loglevel_default -> logCutoff and setLogCutoff
cdio_warn -> putLog LogWarn

Sound.Libcdio.Logging

Most functions have been re-contextulized as being provided through a LibcdioLogger instance, but the interface is otherwise unchanged.

Synopsis

data LogEntry = LogEntry {
- logLevel :: LogLevel
- logMessage :: String
}
data LogLevel
- = LogDebug
- | LogInfo
- | LogWarn
- | LogError
- | LogAssert
putLog :: LogEntry -> IO ()
readLog :: IO [LogEntry]
clearLog :: IO ()
logCutoff :: IO LogLevel
setLogCutoff :: LogLevel -> IO ()
setupLogger :: IO ()

Types

data LogEntry #

An unstructured message emitted from the library to let the user know what's going on behind the scenes.

Constructors

LogEntry
Fields logLevel :: LogLevel How critical it is that the user receive this particular message. logMessage :: String The text of the message itself.

Instances

Instances details

Eq LogEntry #
Instance details Defined in Foreign.Libcdio.Logging Methods (==) :: LogEntry -> LogEntry -> Bool # (/=) :: LogEntry -> LogEntry -> Bool #
Read LogEntry #
Instance details Defined in Foreign.Libcdio.Logging Methods readsPrec :: Int -> ReadS LogEntry # readList :: ReadS [LogEntry] # readPrec :: ReadPrec LogEntry # readListPrec :: ReadPrec [LogEntry] #
Show LogEntry #
Instance details Defined in Foreign.Libcdio.Logging Methods showsPrec :: Int -> LogEntry -> ShowS # show :: LogEntry -> String # showList :: [LogEntry] -> ShowS #
Storable LogEntry #
Instance details Defined in Foreign.Libcdio.Logging Methods sizeOf :: LogEntry -> Int # alignment :: LogEntry -> Int # peekElemOff :: Ptr LogEntry -> Int -> IO LogEntry # pokeElemOff :: Ptr LogEntry -> Int -> LogEntry -> IO () # peekByteOff :: Ptr b -> Int -> IO LogEntry # pokeByteOff :: Ptr b -> Int -> LogEntry -> IO () # peek :: Ptr LogEntry -> IO LogEntry # poke :: Ptr LogEntry -> LogEntry -> IO () #

data LogLevel #

How much detail should be recorded in the logs.

Constructors

LogDebug
LogInfo
LogWarn
LogError
LogAssert

Instances

Instances details

Bounded LogLevel #
Instance details Defined in Foreign.Libcdio.Types.Enums Methods minBound :: LogLevel # maxBound :: LogLevel #
Enum LogLevel #
Instance details Defined in Foreign.Libcdio.Types.Enums Methods succ :: LogLevel -> LogLevel # pred :: LogLevel -> LogLevel # toEnum :: Int -> LogLevel # fromEnum :: LogLevel -> Int # enumFrom :: LogLevel -> [LogLevel] # enumFromThen :: LogLevel -> LogLevel -> [LogLevel] # enumFromTo :: LogLevel -> LogLevel -> [LogLevel] # enumFromThenTo :: LogLevel -> LogLevel -> LogLevel -> [LogLevel] #
Eq LogLevel #
Instance details Defined in Foreign.Libcdio.Types.Enums Methods (==) :: LogLevel -> LogLevel -> Bool # (/=) :: LogLevel -> LogLevel -> Bool #
Ord LogLevel #
Instance details Defined in Foreign.Libcdio.Types.Enums Methods compare :: LogLevel -> LogLevel -> Ordering # (<) :: LogLevel -> LogLevel -> Bool # (<=) :: LogLevel -> LogLevel -> Bool # (>) :: LogLevel -> LogLevel -> Bool # (>=) :: LogLevel -> LogLevel -> Bool # max :: LogLevel -> LogLevel -> LogLevel # min :: LogLevel -> LogLevel -> LogLevel #
Read LogLevel #
Instance details Defined in Foreign.Libcdio.Types.Enums Methods readsPrec :: Int -> ReadS LogLevel # readList :: ReadS [LogLevel] # readPrec :: ReadPrec LogLevel # readListPrec :: ReadPrec [LogLevel] #
Show LogLevel #
Instance details Defined in Foreign.Libcdio.Types.Enums Methods showsPrec :: Int -> LogLevel -> ShowS # show :: LogLevel -> String # showList :: [LogLevel] -> ShowS #

Message interaction

putLog :: LogEntry -> IO () #

Append a message to the logs.

readLog :: IO [LogEntry] #

Retrieve all messages currently in the log for further processing. Note that this retains the contents of the log for future calls; to remove them, a separate call to clearLog must be made.

>>> setupLogger
>>> putLog $ LogEntry LogWarn "Testing log reading"
>>> readLog
[LogEntry LogWarn "Testing log reading"]
>>> readLog
[LogEntry LogWarn "Testing log reading"]
>>> clearLog
>>> readLog
[]

clearLog :: IO () #

Empty all messages currently in the log. There is no way to selectively remove only some messages; if that is desired, call readLog first:

>>> setupLogger
>>> msgs <- readLog
>>> clearLog
>>> mapM_ putLog $ filter p msgs

Management

logCutoff :: IO LogLevel #

Check the current minimum severity which will be recorded in the logs.

See setLogCutoff.

setLogCutoff :: LogLevel -> IO () #

Set the minimum severity required for a message to be recorded in the logs.

See logCutoff.

setupLogger :: IO () #

Initialize the log-management backend to use the mechanisms provided by this library instead of just printing to standard output. While this will usually be taken care of automatically, it may still be necessary to call this explicitly if messages are being recorded before any disc session is opened.