72 lines
1.9 KiB
Markdown
72 lines
1.9 KiB
Markdown
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# Dynamic content
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Use `(foo)` syntax to splice in the value of `foo` at runtime. Any HTML special characters are escaped by default.
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```rust
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let best_pony = "Pinkie Pie";
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let numbers = [1, 2, 3, 4];
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html! {
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p { "Hi, " (best_pony) "!" }
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p {
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"I have " (numbers.len()) " numbers, "
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"and the first one is " (numbers[0])
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}
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}
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```
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Arbitrary Rust code can be included in a splice by using a [block](https://doc.rust-lang.org/reference.html#block-expressions). This can be helpful for complex expressions that would be difficult to read otherwise.
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```rust
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html! {
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p {
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({
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let f: Foo = something_convertible_to_foo()?;
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f.time().format("%H%Mh")
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})
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}
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}
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```
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## Splices in attributes
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Splices work in attributes as well.
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```rust
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let secret_message = "Surprise!";
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html! {
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p title=(secret_message) {
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"Nothing to see here, move along."
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}
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}
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```
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To concatenate multiple values within an attribute, wrap the whole thing in braces. This syntax is useful for building URLs.
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```rust
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const GITHUB: &'static str = "https://github.com";
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html! {
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a href={ (GITHUB) "/lfairy/maud" } {
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"Fork me on GitHub"
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}
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}
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```
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## What can be spliced?
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You can splice any value that implements [`std::fmt::Display`][Display]. Most primitive types (such as `str` and `i32`) implement this trait, so they should work out of the box.
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To change this behavior for some type, you can implement the [`Render`][Render] trait by hand. The [`PreEscaped`][PreEscaped] wrapper type, which outputs its argument without escaping, works this way. See the [traits](./traits.md) section for details.
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```rust
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use maud::PreEscaped;
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let post = "<p>Pre-escaped</p>";
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html! {
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h1 { "My super duper blog post" }
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(PreEscaped(post))
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}
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```
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[Display]: http://doc.rust-lang.org/std/fmt/trait.Display.html
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[Render]: https://docs.rs/maud/*/maud/trait.Render.html
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[PreEscaped]: https://docs.rs/maud/*/maud/struct.PreEscaped.html
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