# template-eyre

An error reporter for panics and `eyre::Report` with handlebars template support.

Ever used [eyre](https://github.com/yaahc/eyre) and finding existing handlers too boring or complex?
This crate enables you to customize your error report and add custom fields
in seconds.

## Features
- [x] Handlebars powered error reports
- [x] Color support
- [x] Custom indent support
- [x] Sensible bundled handlers
- [ ] Backtrace support
- [ ] Panic handler
- [x] Custom fields support

## Write your own template

This crate includes two templates `Hook::simple` and `Hook::colored_simple`,
but you can always create your own templates easily!

First, get started by reading the [handlebars guide](https://handlebarsjs.com/guide/).
Handlebars is a simple template language, so this won't be hard.

Next, start writing your own template! You may gain some idea from [builtin templates](src/templates/).

Notice that this crate provides you with [some handy helpers](#additional-helpers).
Also, the `handlebars` crate this crate depends on also has some [custom helpers](https://docs.rs/handlebars/latest/handlebars/#built-in-helpers).

## Example

A minimal handler can be built with a template like this:

```handlebars
Oh no, this program crashed!

{{style "red" error}}
{{*set multi=(gt (len sources) 1)}}
{{#each sources}}
    {{#if @first}}
        {{~style "dim" "Caused by:"}}
    {{/if}}
    {{~indent (_if @root.multi @index null) (style "yellow" this)}}
{{/each}}

{{style "cyan" "Please report this issue to ..."}}
```

and you get a flavored error report:

![snapshot](https://raw.githubusercontent.com/PhotonQuantum/template-eyre/master/snapshot.png)

## Additional helpers

### `style` helper

Color the output. Styles should be written at its "dotted" form.
 
See [console's document](https://docs.rs/console/latest/console/struct.Style.html#implementations) for details.

E.g., `{{style "black.bold.on_red" error}}`

### `indent` helper

Indent a block.

This helper has three forms:

- `indent content` - Indent the content by four spaces.
- `indent <number> content` - Insert a number before the first line with the same indentation level as backtraces.
- `indent <string> content` - Insert given string before every line.

E.g., `{{indent @index this}}`

### inline `_if` helper

Inline version of `if` helper.

E.g., `{{_if success "Yay!" "Oops!"}}`

### `set` decorator

Set local variables.

E.g., `{{*set flag=true}}`

### `concat` helper

Concatenate strings.

E.g., `{{concat "a" "b"}}`

## License
This project is licensed under [MIT License](LICENSE.txt).