Function safeGetLazy

  • safeGetLazy<T>(cb, defValue): ILazyValue<T>

  • Create and return an readonly ILazyValue instance which will cache and return the value returned by the callback function. The callback function will only be called once, multiple access of the value does not cause re-execution of the callback as the result from the first call is cached internally. If the callback throws the default value will be returned.

    Type Parameters

    • T = boolean

    Parameters

    • cb: (() => T)

      The callback function to fetch the value to be lazily evaluated and cached

        • (): T

        • Returns T

    • defValue: T

      The default value to return when an exception is thrown

    Returns ILazyValue<T>

    A new readonly ILazyValue instance which wraps the callback and will be used to cache the result of the callback

    Since

    0.9.5

    Example

    // This does not cause the evaluation to occur
    let cachedValue = safeGetLazy(() => callSomeExpensiveFunctionWhichMightThrow(), "someDefaultValue");
    let theValue;

    // Just checking if there is an object still does not cause the evaluation
    if (cachedValue) {
        // This will cause the evaluation to occur and the result will be cached
        theValue = cachedValue.v;
    }

    // Accessing the value again will not cause the re-evaluation to occur, it will just return the same
    // result value again.
    theValue === cachedValue.v;  // true

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