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Add application development page

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David Tolnay 2017-05-03 18:09:17 -07:00
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2
src/SUMMARY.md
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@ -5,4 +5,4 @@
- [Basics](basics.md)
- [Concurrency](concurrency.md)
- [Application development]
- [Application development](app.md)

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src/cli_parsing.md → src/app.md
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# Clap Example
# Application development
| Recipe | Crates |
|--------|--------|
| [Parse command line arguments][ex-clap-basic] | [![clap-badge]][clap] |
[ex-clap-basic]: #ex-clap-basic
<a name="ex-clap-basic"></a>
## Parse command line arguments
[![clap-badge]][clap]
## Parse values passed to the program through command line
```rust
/**
* An example of commandline argument parsing, with
* focus on using the clap library tools.
*/
// Argument parsing
extern crate clap;
use clap::{Arg, App};
@ -59,22 +60,34 @@ fn main() {
}
```
The purpose of this is to display the raw power of the clap library, an extensive command line argument parser for Rust. First, the user writes a description for their App, given a version, author, and about string.
The purpose of this is to display the raw power of the clap library, an
extensive command line argument parser for Rust. First, the user writes a
description for their App, given a version, author, and about string.
The next step involves describing the args that clap can expect. 'with_name' is the option or argument descriptor that 'value_of' uses to get the value passed. 'short' and 'long' sets the version to be passed with characters '-' and '--', respectively, through the command line. 'value_name' is simply cosmetic, and is NOT used in getting any actual values. 'help' allows the user to describe what the argument is used for or what the argument expects. If 'takes_value' is set to true, it will expect the argument to take a value, such as a string, filename, or number, as in the example above. For more examples of usage and a description of what clap is capable of, please visit their [wiki](https://kbknapp.github.io/clap-rs/clap/struct.App.html).
The next step involves describing the args that clap can expect. 'with_name' is
the option or argument descriptor that 'value_of' uses to get the value passed.
'short' and 'long' sets the version to be passed with characters '-' and '--',
respectively, through the command line. 'value_name' is simply cosmetic, and is
NOT used in getting any actual values. 'help' allows the user to describe what
the argument is used for or what the argument expects. If 'takes_value' is set
to true, it will expect the argument to take a value, such as a string,
filename, or number, as in the example above. For more examples of usage and a
description of what clap is capable of, please visit their
[wiki](https://kbknapp.github.io/clap-rs/clap/struct.App.html).
We can test this program by running command similar to the following:
```
cargo run -- -f myfile.txt -i "I <3 Rust!!!" --count 6
```
```
> The file passed is: myfile.txt
> The string passed is: I <3 Rust!!!
> The value of the number passed plus 5 is: 11
```
<!-- Links -->
<!-- Crates -->
[clap-badge]: https://img.shields.io/crates/v/clap.svg?label=clap
[clap]: https://docs.rs/clap
[clap]: https://docs.rs/clap/

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src/intro.md
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<!-- Examples -->
[ex-byteorder-le]: basics.html#ex-byteorder-le
[ex-clap-basic]: todo
[ex-clap-basic]: app.html#ex-clap-basic
[ex-json-basic]: todo
[ex-petgraph-basic]: basics.html#ex-petgraph-basic
[ex-rand-custom]: basics.html#ex-rand-custom