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

1 files changed, 40 insertions, 0 deletions

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);
+}