scrhartley opened a new pull request, #106:
URL: https://github.com/apache/freemarker/pull/106
The current `switch` directive is not recommended due to its fall-through
behavior being regarded as error-prone. To solve this problem, we introduce a
new `on` directive as an alternative to `case`, which doesn't support
fall-through. This new directive allows specifying multiple comma-separated
conditions in order to address the primary motivator for using fall-through
with `case`.
## Example
Using `case`:
```freemarker
<#switch animal.size>
<#case "tiny">
<#case "small">
This will be processed if it is small
<#break>
<#case "medium">
This will be processed if it is medium
<#break>
<#default>
This will be processed if it is neither
</#switch>
```
Using `on`:
```freemarker
<#switch animal.size>
<#on "tiny", "small">
This will be processed if it is small
<#on "medium">
This will be processed if it is medium
<#default>
This will be processed if it is neither
</#switch>
```
## Details
* Mixing `case` and `on` directives is disallowed and will fail.
* If a `switch` contains an `on`, then using `break` or `continue` is not
supported (applying to both `on` and `default`). In this situation, `break` and
`continue` will follow the behavior of the containing scope, e.g. of a
containing `list`. This does mean that if someone accidentally uses `break`
with `on`, they could potentially become confused.
### Additional Notes
* When `on` is not used, the legacy behavior for `case`/`default` is that
`continue` will be treated as `break`. If we wish to change this, then that
work can be done separately.
* If using `default`, the parser also allows it to appear before or between
`case` directives, but when using `on` then `default` is only allowed after.
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