PHP命令行调用类方法报错：未定义函数及$this使用错误

The errors you're hitting stem from misunderstanding how class methods work in PHP—you can’t call them like standalone functions, nor use $this without an existing object instance. Here’s how to fix this:

Option 1: Instantiate the class first #

Since your test() method is a non-static public method, you need to create an instance of the DatasetTest class before invoking the method on that object.

Replace your command with this:

$ php -r 'require "DatasetTest.php"; $testInstance = new DatasetTest(); $testInstance->test();'

This creates a new DatasetTest object, then calls the test() method on it—you’ll see the "worked" output as expected.

Option 2: Make the method static (if applicable) #

If your test() method doesn’t rely on any class properties or instance-specific logic, you can modify it to be static. This lets you call it directly using the class name, no instantiation needed.

Update your DatasetTest.php code to:

class DatasetTest { 
    public static function test() { 
        echo "worked"; 
    } 
}

Then run this command:

$ php -r 'require "DatasetTest.php"; DatasetTest::test();'

Why your previous attempts failed: #

• Calling test() directly: PHP searches for a global function named test(), but your method is tied to the DatasetTest class—so it can’t locate it.
• Using $this->test(): $this only refers to the current object instance, and it’s only valid inside a class method. Outside of that context, there’s no object to reference, hence the error.

内容的提问来源于stack exchange，提问作者Paul Kendal