From 5e20a29b4fdc8a2d442d1093681b396dcb4b816b Mon Sep 17 00:00:00 2001 From: Robin Krahl Date: Tue, 7 Jan 2020 11:18:04 +0000 Subject: Add structopt dependency in version 0.3.7 This patch series replaces argparse with structopt in the argument handling code. As a first step, we need structopt as a dependency. Import subrepo structopt/:structopt at efbdda4753592e27bc430fb01f7b9650b2f3174d Import subrepo bitflags/:bitflags at 30668016aca6bd3b02c766e8347e0b4080d4c296 Import subrepo clap/:clap at 784524f7eb193e35f81082cc69454c8c21b948f7 Import subrepo heck/:heck at 093d56fbf001e1506e56dbfa38631d99b1066df1 Import subrepo proc-macro-error/:proc-macro-error at 6c4cfe79a622c5de8ae68557993542be46eacae2 Import subrepo proc-macro2/:proc-macro2 at d5d48eddca4566e5438e8a2cbed4a74e049544de Import subrepo quote/:quote at 727436c6c137b20f0f34dde5d8fda2679b9747ad Import subrepo rustversion/:rustversion at 0c5663313516263059ce9059ef81fc7a1cf655ca Import subrepo syn-mid/:syn-mid at 5d3d85414a9e6674e1857ec22a87b96e04a6851a Import subrepo syn/:syn at e87c27e87f6f4ef8919d0372bdb056d53ef0d8f3 Import subrepo textwrap/:textwrap at abcd618beae3f74841032aa5b53c1086b0a57ca2 Import subrepo unicode-segmentation/:unicode-segmentation at 637c9874c4fe0c205ff27787faf150a40295c6c3 Import subrepo unicode-width/:unicode-width at 3033826f8bf05e82724140a981d5941e48fce393 Import subrepo unicode-xid/:unicode-xid at 4baae9fffb156ba229665b972a9cd5991787ceb7 --- clap/examples/10_default_values.rs | 40 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) create mode 100644 clap/examples/10_default_values.rs (limited to 'clap/examples/10_default_values.rs') diff --git a/clap/examples/10_default_values.rs b/clap/examples/10_default_values.rs new file mode 100644 index 0000000..ca50981 --- /dev/null +++ b/clap/examples/10_default_values.rs @@ -0,0 +1,40 @@ +extern crate clap; + +use clap::{App, Arg}; + +fn main() { + // There are two ways in which to get a default value, one is to use claps Arg::default_value + // method, and the other is to use Rust's built in Option::unwrap_or method. + // + // I'll demo both here. + // + // First, we'll use clap's Arg::default_value with an "INPUT" file. + let matches = App::new("myapp").about("does awesome things") + .arg(Arg::with_name("INPUT") + .help("The input file to use") // Note, we don't need to specify + // anything like, "Defaults to..." + // because clap will automatically + // generate that for us, and place + // it in the help text + .default_value("input.txt") + .index(1)) + + // Next we'll use the Option::unwrap_or method on this "CONFIG" option + .arg(Arg::with_name("CONFIG") + // Note that we have to manually include some verbiage to the user + // telling them what the default will be. + .help("The config file to use (default is \"config.json\")") + .short("c") + .takes_value(true)) + .get_matches(); + + // It's safe to call unwrap because the value with either be what the user input at runtime + // or "input.txt" + let input = matches.value_of("INPUT").unwrap(); + + // Using Option::unwrap_or we get the same affect, but without the added help text injection + let config_file = matches.value_of("CONFIG").unwrap_or("config.json"); + + println!("The input file is: {}", input); + println!("The config file is: {}", config_file); +} -- cgit v1.2.3