Distribution.Simple.Program.Db

This provides a ProgramDb type which holds configured and not-yet configured programs. It is the parameter to lots of actions elsewhere in Cabal that need to look up and run programs. If we had a Cabal monad, the ProgramDb would probably be a reader or state component of it.

One nice thing about using it is that any program that is registered with Cabal will get some "configure" and ".cabal" helpers like --with-foo-args --foo-path= and extra-foo-args.

There's also a hook for adding programs in a Setup.lhs script. See hookedPrograms in UserHooks. This gives a hook user the ability to get the above flags and such so that they don't have to write all the PATH logic inside Setup.lhs.

The collection of configured programs we can run

data ProgramDb

The configuration is a collection of information about programs. It contains information both about configured programs and also about programs that we are yet to configure.

The idea is that we start from a collection of unconfigured programs and one by one we try to configure them at which point we move them into the configured collection. For unconfigured programs we record not just the Program but also any user-provided arguments and location for the program.

Instances

Read ProgramDb

Show ProgramDb

Binary ProgramDb

emptyProgramDb :: ProgramDb

defaultProgramDb :: ProgramDb

restoreProgramDb :: [Program] -> ProgramDb -> ProgramDb

The Read/Show instance does not preserve all the unconfigured Programs because Program is not in Read/Show because it contains functions. So to fully restore a deserialised ProgramDb use this function to add back all the known Programs.

• It does not add the default programs, but you probably want them, use builtinPrograms in addition to any extra you might need.

Query and manipulate the program db

addKnownProgram :: Program -> ProgramDb -> ProgramDb

Add a known program that we may configure later

addKnownPrograms :: [Program] -> ProgramDb -> ProgramDb

lookupKnownProgram :: String -> ProgramDb -> Maybe Program

knownPrograms :: ProgramDb -> [(Program, Maybe ConfiguredProgram)]

getProgramSearchPath :: ProgramDb -> ProgramSearchPath

Get the current ProgramSearchPath used by the ProgramDb. This is the default list of locations where programs are looked for when configuring them. This can be overridden for specific programs (with userSpecifyPath), and specific known programs can modify or ignore this search path in their own configuration code.

setProgramSearchPath :: ProgramSearchPath -> ProgramDb -> ProgramDb

Change the current ProgramSearchPath used by the ProgramDb. This will affect programs that are configured from here on, so you should usually set it before configuring any programs.

modifyProgramSearchPath :: (ProgramSearchPath -> ProgramSearchPath) -> ProgramDb -> ProgramDb

Modify the current ProgramSearchPath used by the ProgramDb. This will affect programs that are configured from here on, so you should usually modify it before configuring any programs.

userSpecifyPath

Arguments

:: String

Program name

-> FilePath

user-specified path to the program

-> ProgramDb

-> ProgramDb

User-specify this path. Basically override any path information for this program in the configuration. If it's not a known program ignore it.

userSpecifyPaths :: [(String, FilePath)] -> ProgramDb -> ProgramDb

Like userSpecifyPath but for a list of progs and their paths.

userMaybeSpecifyPath :: String -> Maybe FilePath -> ProgramDb -> ProgramDb

userSpecifyArgs

Arguments

:: String

Program name

-> [ProgArg]

user-specified args

-> ProgramDb

-> ProgramDb

User-specify the arguments for this program. Basically override any args information for this program in the configuration. If it's not a known program, ignore it..

userSpecifyArgss :: [(String, [ProgArg])] -> ProgramDb -> ProgramDb

Like userSpecifyPath but for a list of progs and their args.

userSpecifiedArgs :: Program -> ProgramDb -> [ProgArg]

Get any extra args that have been previously specified for a program.

lookupProgram :: Program -> ProgramDb -> Maybe ConfiguredProgram

Try to find a configured program

updateProgram :: ConfiguredProgram -> ProgramDb -> ProgramDb

Update a configured program in the database.

configuredPrograms :: ProgramDb -> [ConfiguredProgram]

List all configured programs.

Query and manipulate the program db

configureProgram :: Verbosity -> Program -> ProgramDb -> IO ProgramDb

Try to configure a specific program. If the program is already included in the collection of unconfigured programs then we use any user-supplied location and arguments. If the program gets configured successfully it gets added to the configured collection.

Note that it is not a failure if the program cannot be configured. It's only a failure if the user supplied a location and the program could not be found at that location.

The reason for it not being a failure at this stage is that we don't know up front all the programs we will need, so we try to configure them all. To verify that a program was actually successfully configured use requireProgram.

configureAllKnownPrograms :: Verbosity -> ProgramDb -> IO ProgramDb

Try to configure all the known programs that have not yet been configured.

lookupProgramVersion :: Verbosity -> Program -> VersionRange -> ProgramDb -> IO (Either String (ConfiguredProgram, Version, ProgramDb))

Check that a program is configured and available to be run.

Additionally check that the program version number is suitable and return it. For example you could require AnyVersion or orLaterVersion (Version [1,0] [])

It returns the configured program, its version number and a possibly updated ProgramDb. If the program could not be configured or the version is unsuitable, it returns an error value.

reconfigurePrograms :: Verbosity -> [(String, FilePath)] -> [(String, [ProgArg])] -> ProgramDb -> IO ProgramDb

reconfigure a bunch of programs given new user-specified args. It takes the same inputs as userSpecifyPath and userSpecifyArgs and for all progs with a new path it calls configureProgram.

requireProgram :: Verbosity -> Program -> ProgramDb -> IO (ConfiguredProgram, ProgramDb)

Check that a program is configured and available to be run.

It raises an exception if the program could not be configured, otherwise it returns the configured program.

requireProgramVersion :: Verbosity -> Program -> VersionRange -> ProgramDb -> IO (ConfiguredProgram, Version, ProgramDb)

Like lookupProgramVersion, but raises an exception in case of error instead of returning 'Left errMsg'.