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Veetaha merged 1 commit into from
Mar 6, 2025
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Update the docs about limitations #256

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9 changes: 6 additions & 3 deletions website/src/guide/troubleshooting/limitations.md
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Expand Up @@ -136,10 +136,13 @@ fn example(

Here is [the related issue](https://github.com/rust-lang/rustfmt/issues/6276) in `rustfmt` about this problem.

## `const` Functions
## `const` Evaluation

It's possible to place `#[builder]` on top of a `const fn`, but the generated builder methods won't be marked `const`. They use the non-const method `Into::into` to transition between type states. Except for that, the generated code should be `const`-compatible.
It's possible to place `#[builder]` on top of a `const fn`, but the generated builder methods won't be marked as `const`. Note that even if `bon` adds support for `const` builders, some features won't work for them. For example:

If you have a strong use case that requires full support for `const`, feel free to [open an issue]. We'll figure something out for sure 🐱.
- `#[builder(default)]` can not work because `Default::default()` is not `const`. You'd have to write `#[builder(default = ...)]` instead to construct the default value manually
- `#[builder(into)]` can not work because `Into::into()` is not `const`

If you have a strong use case that requires full support for `const`, feel free to leave a 👍 on [this issue](https://github.com/elastio/bon/issues/169).

[open an issue]: https://github.com/elastio/bon/issues
2 changes: 1 addition & 1 deletion website/src/guide/typestate-api/builder-fields.md
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Expand Up @@ -79,7 +79,7 @@ assert_eq!(x1, 99);

## Custom Fields

This is useful if you'd like a completely custom state for [custom setters](./custom-methods) in the builder.
Custom fields are useful if you'd like a completely custom state for [custom setters](./custom-methods) in the builder.

To understand how it works, we'll create a builder API _similar_ to [`std::process::Command`](https://doc.rust-lang.org/stable/std/process/struct.Command.html) where you have a couple of methods [`arg`](https://doc.rust-lang.org/stable/std/process/struct.Command.html#method.arg) and [`args`](https://doc.rust-lang.org/stable/std/process/struct.Command.html#method.args), that push values into an internal arguments `Vec`.

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