hflags: Command line flag parser, very similar to Google's gflags
The HFlags
library supports easy definition of command line flags,
reimplementing the ideas from Google's gflags
(http://code.google.com/p/gflags).
Command line flags can be declared in any file at the toplevel,
using defineFlag
. At runtime, the actual values are assigned to
the toplevel flags_name
constants. Those can be used purely
throughout the program.
At the beginning of the main
function, $initHFlags "program
description"
has to be called to initialize the flags. All flags
will be initialized that are transitively reachable via imports from
main
. This means, that any Haskell package can easily define
command line flags with HFlags
. This feature is demonstrated by
http://github.com/errge/hflags/blob/master/examples/ImportExample.hs
and http://github.com/errge/hflags/tree/master/examples/package.
A simple example (more in the http://github.com/errge/hflags/tree/master/examples directory):
#!/usr/bin/env runhaskell {-# LANGUAGE TemplateHaskell #-} import HFlagsdefineFlag
"name" "Indiana Jones" "Who to greet."defineFlag
"r:repeat" (3 + 4 :: Int) "Number of times to repeat the message." main = do s <- $initHFlags "Simple program v0.1" sequence_ $ replicate flags_repeat greet putStrLn $ "Your additional arguments were: " ++ show s putStrLn $ "Which is the same as: " ++ show HFlags.arguments where greet = putStrLn $ "Hello " ++ flags_name ++ ", very nice to meet you!"
At initHFlags
time, the library also tries to gather flags out of
environment variables. HFLAGS_verbose=True
is equivalent to
specify --verbose=True. This environment feature only works with
long options and the user has to specify a value even for Bools.
Since version 0.2, you mustn't put the initHFlags in a parentheses with the program description. Just $initHFlags
, it's cleaner.
See http://github.com/errge/hflags/tree/master/changelog for recent changes.
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Versions [RSS] | 0.1, 0.1.1, 0.1.2, 0.1.3, 0.2, 0.3, 0.4, 0.4.1, 0.4.2, 0.4.3 |
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Change log | changelog |
Dependencies | base (>=4.6 && <5), containers (>=0.4), template-haskell (>=2.8), text (>=0.11) [details] |
License | Apache-2.0 |
Author | Mihaly Barasz <klao@google.com>, Gergely Risko <gergely@risko.hu> |
Maintainer | Gergely Risko <gergely@risko.hu> |
Category | Console |
Home page | http://github.com/errge/hflags |
Bug tracker | http://github.com/errge/hflags/issues |
Source repo | head: git clone http://github.com/errge/hflags |
Uploaded | by MihalyBarasz at 2017-12-05T17:08:46Z |
Distributions | NixOS:0.4.3 |
Reverse Dependencies | 6 direct, 4 indirect [details] |
Downloads | 10816 total (31 in the last 30 days) |
Rating | 2.0 (votes: 1) [estimated by Bayesian average] |
Your Rating | |
Status | Docs available [build log] Last success reported on 2017-12-05 [all 1 reports] |