--- The CommandLine module handles parsing of the command-line options.
+-- |The CommandLine module handles parsing of the command-line options.
-- It should more or less be a black box, providing Main with only the
-- information it requires.
-
module CommandLine
( help_set,
help_text,
--- A record containing values for all available options.
+-- |A record containing values for all available options.
data Options = Options { opt_help :: Bool,
opt_from :: Maybe String,
opt_to :: Maybe String }
--- This constructs an instance of Options, with each of its members
--- set to default values.
+-- |Constructs an instance of Options, with each of its members set to
+-- default values.
default_options :: Options
default_options = Options { opt_help = False,
opt_from = Nothing,
opt_to = Nothing }
--- The options list that we construct associates a function with each
+-- |The options list that we construct associates a function with each
-- option. This function is responsible for updating an Options record
-- with the appropriate value.
--
-- For more information and an example of this idiom, see,
--
--- http://www.haskell.org/haskellwiki/High-level_option_handling_with_GetOpt
+-- <http://www.haskell.org/haskellwiki/High-level_option_handling_with_GetOpt>
--
options :: [OptDescr (Options -> IO Options)]
options =
Option ['t'][] (ReqArg set_to "email_address") "Send tweets TO email_address.",
Option ['f'][] (ReqArg set_from "email_address") "Send tweets FROM email_address."
]
-
+
set_help :: Options -> IO Options
set_help opts = do
set_from :: String -> Options -> IO Options
set_from arg opts = do
return opts { opt_from = Just arg }
-
+
-- The usage header.
usage :: String
return opts
+-- |Parse errors relating to the list of usernames.
username_errors :: IO [String]
username_errors = do
argv <- getArgs
else return []
+-- |Parse errors relating to the "To" address.
to_errors :: IO [String]
to_errors = do
toaddr <- to_email_address
then return ["\"From\" address specified without \"To\" address."]
else return []
+
+-- |Parse errors relating to the "From" address.
from_errors :: IO [String]
from_errors = do
toaddr <- to_email_address
else return []
+-- |Format an error message for printing.
format_error :: String -> String
format_error err = "ERROR: " ++ err ++ "\n"
--- Return a list of errors.
+-- |Return a list of all parse errors.
parse_errors :: IO [String]
parse_errors = do
argv <- getArgs
- let (_, _, errors) = getOpt Permute options argv
+ let (_, _, errors) = getOpt Permute options argv
errs_username <- username_errors
errs_to <- to_errors
errs_from <- from_errors
return $ map format_error (errors ++ errs_username ++ errs_to ++ errs_from)
--- Is the help option set?
+-- |Was the "help" option passed on the command line?
help_set :: IO Bool
help_set = do
opts <- parse_options
return (opt_help opts)
+-- |What "To" address was given on the command line?
to_email_address :: IO (Maybe String)
to_email_address = do
opts <- parse_options
return (opt_to opts)
+-- |What "From" address was given on the command line?
from_email_address :: IO (Maybe String)
from_email_address = do
opts <- parse_options
return (opt_from opts)
-
+
+-- |What usernames were passed on the command line?
parse_usernames :: IO [String]
parse_usernames = do
argv <- getArgs