kotlin let in two variables

119
// Example usage:

val risk = safeLet(person.name, person.age) { name, age ->
  // do something
}

// Extension functions
inline fun <T1: Any, T2: Any, R: Any> safeLet(p1: T1?, p2: T2?, block: (T1, T2)->R?): R? {
    return if (p1 != null && p2 != null) block(p1, p2) else null
}
inline fun <T1: Any, T2: Any, T3: Any, R: Any> safeLet(p1: T1?, p2: T2?, p3: T3?, block: (T1, T2, T3)->R?): R? {
    return if (p1 != null && p2 != null && p3 != null) block(p1, p2, p3) else null
}
inline fun <T1: Any, T2: Any, T3: Any, T4: Any, R: Any> safeLet(p1: T1?, p2: T2?, p3: T3?, p4: T4?, block: (T1, T2, T3, T4)->R?): R? {
    return if (p1 != null && p2 != null && p3 != null && p4 != null) block(p1, p2, p3, p4) else null
}
inline fun <T1: Any, T2: Any, T3: Any, T4: Any, T5: Any, R: Any> safeLet(p1: T1?, p2: T2?, p3: T3?, p4: T4?, p5: T5?, block: (T1, T2, T3, T4, T5)->R?): R? {
    return if (p1 != null && p2 != null && p3 != null && p4 != null && p5 != null) block(p1, p2, p3, p4, p5) else null
}

// ...keep going up to the parameter count you care about
// Here are a few variations, depending on what style you will want to use, if you have everything of same or different types, and if the list unknown number of items...

Mixed types, all must not be null to calculate a new value
For mixed types you could build a series of functions for each parameter count that may look silly, but work nicely for mixed types:

inline fun <T1: Any, T2: Any, R: Any> safeLet(p1: T1?, p2: T2?, block: (T1, T2)->R?): R? {
    return if (p1 != null && p2 != null) block(p1, p2) else null
}
inline fun <T1: Any, T2: Any, T3: Any, R: Any> safeLet(p1: T1?, p2: T2?, p3: T3?, block: (T1, T2, T3)->R?): R? {
    return if (p1 != null && p2 != null && p3 != null) block(p1, p2, p3) else null
}
inline fun <T1: Any, T2: Any, T3: Any, T4: Any, R: Any> safeLet(p1: T1?, p2: T2?, p3: T3?, p4: T4?, block: (T1, T2, T3, T4)->R?): R? {
    return if (p1 != null && p2 != null && p3 != null && p4 != null) block(p1, p2, p3, p4) else null
}
inline fun <T1: Any, T2: Any, T3: Any, T4: Any, T5: Any, R: Any> safeLet(p1: T1?, p2: T2?, p3: T3?, p4: T4?, p5: T5?, block: (T1, T2, T3, T4, T5)->R?): R? {
    return if (p1 != null && p2 != null && p3 != null && p4 != null && p5 != null) block(p1, p2, p3, p4, p5) else null
}

// ...keep going up to the parameter count you care about

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