kinow commented on code in PR #181:
URL:
https://github.com/apache/commons-configuration/pull/181#discussion_r873569935
##########
src/main/java/org/apache/commons/configuration2/interpol/ConfigurationInterpolator.java:
##########
@@ -281,13 +301,34 @@ public ConfigurationInterpolator getParentInterpolator() {
* @return the {@code StringSubstitutor} used by this object
*/
private StringSubstitutor initSubstitutor() {
- return new StringSubstitutor(key -> Objects.toString(resolve(key),
null));
+ return new StringSubstitutor(key -> {
+ final Object value = resolve(key);
+ return value != null
+ ? stringConverter.apply(value)
+ : null;
+ });
}
/**
- * Performs interpolation of the passed in value. If the value is of type
String, this method checks whether it contains
- * variables. If so, all variables are replaced by their current values
(if possible). For non string arguments, the
- * value is returned without changes.
+ * Performs interpolation of the passed in value. If the value is of type
{@code String}, this method checks
+ * whether it contains variables. If so, all variables are replaced by
their current values (if possible). For
+ * non string arguments, the value is returned without changes. In the
special case where the value is a string
+ * consisting of a single variable reference, the interpolated variable
value is <em>not</em> converted to a
+ * string before returning, so that callers can access the raw value.
However, if the variable is part of a larger
+ * interpolated string, then the variable value is converted to a string
using the configured
+ * {@link #getStringConverter() string converter}. (See the discussion on
string conversion in the class
+ * documentation for more details.)
+ *
+ * <p><strong>Examples</strong></p>
+ * <p>
+ * For the following examples, assume that the default string conversion
function is in place and that the
+ * variable {@code i} maps to the integer value {@code 42}.
+ * <pre>
+ * interpolator.interpolate(1) -> 1// non-string argument returned
unchanged
Review Comment:
>->
You can also use the pirate symbol (that's how I remember it): `&rarr`
(`→`), and `←` for left-arrow :+1: But this way is fine too (only noticed
because for one second I thought it was a mistake.)
##########
src/test/java/org/apache/commons/configuration2/TestAbstractConfigurationBasicFeatures.java:
##########
@@ -200,7 +200,7 @@ private void checkGetStringArrayScalar(final Object value) {
final BaseConfiguration config = new BaseConfiguration();
config.addProperty(KEY_PREFIX, value);
final String[] array = config.getStringArray(KEY_PREFIX);
- assertEquals("Weong number of elements", 1, array.length);
+ assertEquals("Wrong number of elements", 1, array.length);
Review Comment:
:+1:
##########
src/main/java/org/apache/commons/configuration2/interpol/ConfigurationInterpolator.java:
##########
@@ -452,4 +511,51 @@ public void setEnableSubstitutionInVariables(final boolean
f) {
public void setParentInterpolator(final ConfigurationInterpolator
parentInterpolator) {
this.parentInterpolator = parentInterpolator;
}
+
+ /** Class encapsulating the default logic to convert resolved variable
values into strings.
+ * This class is thread-safe.
+ */
+ private static final class DefaultStringConverter implements
Function<Object, String> {
+
+ /** Shared instance. */
+ static final DefaultStringConverter INSTANCE = new
DefaultStringConverter();
+
+ /** {@inheritDoc} */
+ @Override
+ public String apply(final Object obj) {
+ return Objects.toString(extractSimpleValue(obj), null);
+ }
+
+ /** Attempt to extract a simple value from {@code obj} for use in
string conversion.
+ * If the input represents a collection of some sort (e.g., an
iterable or array),
+ * the first item from the collection is returned.
+ * @param obj input object
+ * @return extracted simple object
+ */
+ private Object extractSimpleValue(final Object obj) {
+ if (!(obj instanceof String)) {
+ if (obj instanceof Iterable) {
+ return nextOrNull(((Iterable<?>) obj).iterator());
+ } else if (obj instanceof Iterator) {
+ return nextOrNull((Iterator<?>) obj);
+ } else if (obj.getClass().isArray()) {
+ return Array.getLength(obj) > 0
+ ? Array.get(obj, 0)
+ : null;
Review Comment:
I think we have Lang in our list of dependencies. So we could use
`ArrayUtils.get` here if you'd like. Same result, not a must-have I believe. I
think it's something like
```
ArrayUtils.get(obj, 0, null)
```
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