嵌套方法调用与单次变量 [英] Nested method calls vs. one-shot variables

问题描述

当嵌套方法调用或使用单稳变量时，最佳做法是什么？

What is the best practice when nesting method calls or using one-shot variables?

应该永远不要使用单稳变量吗？

Should you never use one-shot variables?

例如：

[persistentStoreCoordinator addPersistentStoreWithType:NSXMLStoreType 
                                         configuration:nil 
                                                   URL:[NSURL fileURLWithPath: [applicationSupportDirectory stringByAppendingPathComponent: @"storedata"]] 
                                               options:[NSDictionary dictionaryWithObject:[NSNumber numberWithBool:YES] forKey:NSMigratePersistentStoresAutomaticallyOption] 
                                                 error:&error];

应该总是将嵌套方法分成单次变量吗？

Should you always break up a nested method into one-shot variables?

例如：

NSNumber *yesNumber = [NSNumber numberWithBool:YES];
NSDictionary *optionsDict = [NSDictionary dictionaryWithObject:yesNumber 
                                                        forKey:NSMigratePersistentStoresAutomaticallyOption];
NSString *urlPath = [applicationSupportDirectory stringByAppendingPathComponent:@"storedata"];
NSURL *url = [NSURL fileURLWithPath: urlPath]; 
[persistentStoreCoordinator addPersistentStoreWithType:NSXMLStoreType 
                                         configuration:nil 
                                                   URL:url
                                               options:optionsDict
                                                 error:&error];

还是应该使用两者的组合？

Or should you use some combination of the two?

例如：

NSDictionary *optionsDict = [NSDictionary dictionaryWithObject:[NSNumber numberWithBool:YES] 
                                                        forKey:NSMigratePersistentStoresAutomaticallyOption];
NSURL *url = [NSURL fileURLWithPath: [applicationSupportDirectory stringByAppendingPathComponent:@"storedata"]]; 
[persistentStoreCoordinator addPersistentStoreWithType:NSXMLStoreType 
                                         configuration:nil 
                                                   URL:url
                                               options:optionsDict
                                                 error:&error];

我倾向于结合两者，但我想听听别人的说这个。如果上面不清楚，这些一次性变量是为了分解嵌套方法而创建的，不会在任何地方使用。

I tend to go with a combination of the two but I would like to hear what everyone else has to say about this. In case it is not clear above, these "one-shot variables" are created for the sole purpose of breaking up the nested method and will not be used anywhere.

推荐答案

我个人认为你应该使用一次性变量，因为它没有任何开销（在发布模式，即优化），它使调试更容易。除非你有特定的理由不要。

Personally I think that you should use "one-shot" variables since it doesn't come with any overhead (in "release" mode, that is with optimization on) and it makes debugging easier. Unless of course you have a specific reason not to.

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