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< h1 id = "easy-doc-initialization" > < a class = "header" href = "#easy-doc-initialization" > Easy doc initialization< / a > < / h1 >
< h2 id = "description" > < a class = "header" href = "#description" > Description< / a > < / h2 >
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< p > If a struct takes significant effort to initialize, when writing docs, it can be
quicker to wrap your example with a helper function which takes the struct as an
argument.< / p >
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< h2 id = "motivation" > < a class = "header" href = "#motivation" > Motivation< / a > < / h2 >
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< p > Sometimes there is a struct with multiple or complicated parameters and several
methods. Each of these methods should have examples.< / p >
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< p > For example:< / p >
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< pre > < code class = "language-rust ignore" > struct Connection {
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name: String,
stream: TcpStream,
}
impl Connection {
/// Sends a request over the connection.
///
/// # Example
/// ```no_run
/// # // Boilerplate are required to get an example working.
/// # let stream = TcpStream::connect(" 127.0.0.1:34254" );
/// # let connection = Connection { name: " foo" .to_owned(), stream };
/// # let request = Request::new(" RequestId" , RequestType::Get, " payload" );
/// let response = connection.send_request(request);
/// assert!(response.is_ok());
/// ```
fn send_request(& self, request: Request) -> Result< Status, SendErr> {
// ...
}
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/// Oh no, all that boilerplate needs to be repeated here!
fn check_status(& self) -> Status {
// ...
}
}
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< / code > < / pre >
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< h2 id = "example" > < a class = "header" href = "#example" > Example< / a > < / h2 >
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< p > Instead of typing all of this boilerplate to create an < code > Connection< / code > and
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< code > Request< / code > it is easier to just create a wrapping helper function which takes
them as arguments:< / p >
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< pre > < code class = "language-rust ignore" > struct Connection {
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name: String,
stream: TcpStream,
}
impl Connection {
/// Sends a request over the connection.
///
/// # Example
/// ```
/// # fn call_send(connection: Connection, request: Request) {
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/// let response = connection.send_request(request);
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/// assert!(response.is_ok());
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/// # }
/// ```
fn send_request(& self, request: Request) {
// ...
}
}
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< / code > < / pre >
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< p > < strong > Note< / strong > in the above example the line < code > assert!(response.is_ok());< / code > will not
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actually run while testing because it is inside a function which is never
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invoked.< / p >
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< h2 id = "advantages" > < a class = "header" href = "#advantages" > Advantages< / a > < / h2 >
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< p > This is much more concise and avoids repetitive code in examples.< / p >
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< h2 id = "disadvantages" > < a class = "header" href = "#disadvantages" > Disadvantages< / a > < / h2 >
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< p > As example is in a function, the code will not be tested. Though it will still be
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checked to make sure it compiles when running a < code > cargo test< / code > . So this pattern is
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most useful when you need < code > no_run< / code > . With this, you do not need to add < code > no_run< / code > .< / p >
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< h2 id = "discussion" > < a class = "header" href = "#discussion" > Discussion< / a > < / h2 >
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< p > If assertions are not required this pattern works well.< / p >
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< p > If they are, an alternative can be to create a public method to create a helper
instance which is annotated with < code > #[doc(hidden)]< / code > (so that users won't see it).
Then this method can be called inside of rustdoc because it is part of the
crate's public API.< / p >
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