Question

// main.m
#import <Foundation/Foundation.h>
#import "Car.h"

int main(int argc, const char * argv[]) {

@autoreleasepool {
    Car *porsche = [[Car alloc] init];
    porsche.model = @"Porsche 911 Carrera";

    SEL stepOne = NSSelectorFromString(@"startEngine");
    SEL stepTwo = @selector(driveForDistance:);
    SEL stepThree = @selector(turnByAngle:quickly:);

    // This is the same as:
    // [porsche startEngine];
    [porsche performSelector:stepOne];

    // This is the same as:
    // [porsche driveForDistance:[NSNumber numberWithDouble:5.7]];
    [porsche performSelector:stepTwo
                  withObject:[NSNumber numberWithDouble:5.7]];

    if ([porsche respondsToSelector:stepThree]) {
        // This is the same as:
        // [porsche turnByAngle:[NSNumber numberWithDouble:90.0]
        //              quickly:[NSNumber numberWithBool:YES]];
        [porsche performSelector:stepThree
                      withObject:[NSNumber numberWithDouble:90.0]
                      withObject:[NSNumber numberWithBool:YES]];
    }
    NSLog(@"Step one: %@", NSStringFromSelector(stepOne));
}
return 0;
}

对于objective-c选择器，其他语言如c ++，python，ruby，java，javascript有类似的东西吗？感谢

Answer 1

是。 C ++具有指向执行类似功能的成员的指针 - 这些标识一个实例方法，然后可以调用该方法，提供调用方法的对象和参数，类似语义（使用动态绑定的模数Objective-C和使用后期绑定的C ++）但是performSelector:withObject:等语法相当不同。

其他人？所有语言都有网上描述......

objective-c选择器，做其他语言如c ++，python，ruby，java，javascript有类似的东西吗？

1 个答案: