Question

您如何以更科学的方式编写以下代码？

var returnValue = ...
val s3data = presignedUrl.body()
if (s3data != null) {
    val uploadImage = api.uploadImage(s3data.bucketUrl, s3data.awsAccessKeyId, s3data.policy, s3data.key, s3data.signature, body).execute()
    if (!uploadImage.isSuccessful) {
        crashReporterService.sendIssue("Failed uploading file", "Failed uploading file ${uploadImage.raw()}")
        returnValue = Result.FAILURE
    } else {
        returnValue = Result.SUCCESS
    }
} else {
    crashReporterService.sendIssue("Failed uploading image", "Error - ${presignedUrl.raw()}")
    returnValue = Result.FAILURE
}

return returnValue

我可以使用let，但我觉得它使代码更难理解

Answer 1

通用共享代码 - 在这种情况下，错误报告和返回失败结果 - 可以合并为local function。
导致返回的可空性（在这种情况下，s3data可以为空）通常可以替换为返回?: elvis operator。
反复键入相同的变量（在这种情况下，访问s3data），run块是合适的。如果感到困惑，请参阅What is a "receiver" in Kotlin?
正如另一个答案所述，if / else块是Kotlin中的表达。

因此，我会发现以下实现最具思想性，但要正确命名本地函数的参数：

fun foo() {
    fun failure(p0: String, p1: String) = crashReporterService.sendIssue(p0, p1).let { Result.FAILURE }
    val s3data = presignedUrl.body() ?: return failure("Failed uploading image", "Error - ${presignedUrl.raw()}")
    val uploadImage = s3data.run { api.uploadImage(bucketUrl, awsAccessKeyId, policy, key, signature, body).execute() }

    return if (uploadImage.isSuccessful) {
        Result.SUCCESS
    } else {
        failure("Failed uploading file", "Failed uploading file ${uploadImage.raw()}")
    }
}

您的问题接近于代码审核，因此您可能也很高兴知道dedicated Stack Exchange network just for that.之前请先阅读A guide to Code Review for Stack Overflow users。

Answer 2

if/else is an expression in Kotlin，所以以下肯定更像是Kotlinesque：

val s3data = presignedUrl.body()
return if (s3data != null) {
    val uploadImage = api.uploadImage(s3data.bucketUrl, s3data.awsAccessKeyId, s3data.policy, s3data.key, s3data.signature, body).execute()
    if (!uploadImage.isSuccessful) {
        crashReporterService.sendIssue("Failed uploading file", "Failed uploading file ${uploadImage.raw()}")
        Result.FAILURE
    } else {
        Result.SUCCESS
    }
} else {
    crashReporterService.sendIssue("Failed uploading image", "Error - ${presignedUrl.raw()}")
    Result.FAILURE
}

什么时候我应该使用let {}和什么时候只是普通！= null

2 个答案: