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Settings pattern is not a way to get an optional setting

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Havoc Pennington 2014-05-03 09:59:42 -04:00
parent 2b4516ab62
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README.md
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@ -317,18 +317,19 @@ options:
`Config`; `ConfigObject` implements `java.util.Map<String,?>` and
the `get()` method on `Map` returns null for missing keys. See
the API docs for more detail on `Config` vs. `ConfigObject`.
6. Consider the "Settings class" pattern with `checkValid()` to
verify that you have all settings when you initialize the
app. See the [Schemas and Validation](#schemas-and-validation)
section of this README for more details.
The *recommended* path (for most cases, in most apps) is that you
require all settings to be present in either `reference.conf` or
`application.conf` and allow `ConfigException.Missing` to be
thrown if they are not. That's the design intent of the `Config`
API design.
If you do need a setting to be optional, checking `hasPath()` in
Consider the "Settings class" pattern with `checkValid()` to
verify that you have all settings when you initialize the
app. See the [Schemas and Validation](#schemas-and-validation)
section of this README for more details on this pattern.
**If you do need a setting to be optional**: checking `hasPath()` in
advance should be the same amount of code (in Java) as checking
for `null` afterward, without the risk of `NullPointerException`
when you forget. In Scala, you could write an enrichment class