What is an extension function? Write a hasWhitespace extension for String.
WHAT IT TESTS: Kotlin extensions are static dispatch, not true members. ANSWER OUTLINE: Explain receiverType.functionName adds behavior without inheritance; write hasWhitespace with any { it.isWhitespace() }. RED FLAG: Extensions modify classes or override.
WHAT IT TESTS: Whether you understand Kotlin extension functions as static dispatch sugar, not real class members. ANSWER OUTLINE: First, define them as behavior added without inheritance via receiverType.functionName syntax; second, stress they do not modify the underlying class and are resolved statically at compile time. Third, implement hasWhitespace with any { it.isWhitespace() } or a regex check. RED FLAG: Claiming extensions override superclass methods, are inherited, or modify third-party bytecode.
Read the original → kotlinlang.org
- #kotlin
- #extension-functions
- #static-dispatch
- #interoperability
- #idiomatic-kotlin
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