blocks|key|959299|text|只需在它们需要之前包含它们，一切都会好起来的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|959300|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Simply include them before they needed and everything will be fine.

blocks|key|959372|text|如果一个类试图使用另一个尚未解析的类，那么就会出现错误。最好的选择是将类放在脚本中，这样依赖关系仍然完好无损。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|959373|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

It would matter as if one class tried to use another which had not yet been parsed, then an error would occur. The best option is to place the classes in the script so the dependancy will still be intact.

blocks|key|1173790|text|如果它们都在同一个文件中，那么顺序应该无关紧要。在极少数情况下(我在名称空间中见过)，顺序确实很重要，但不要太担心这一点，除非您正在挑战极限。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1173791|试试看。最坏的情况是它会给你一个错误...|1173792|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

If they all are in the same file, no the order shouldn't matter. There are some rare instances (I've seen with namespaces) where the order does matter, but don't worry about that too much unless you're pushing the envelope. 

Try it. The worst that can happen is that it'll give you an error...

blocks|key|1173875|text|在一个PHP文件中，您可以在任何地方声明函数/类，并在任何地方(在该文件中)调用它们，顺序并不重要。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1173876|至于包含，在尝试在该文件中使用已声明的函数/类之前，必须包含该文件。|1173877|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

Within 1 PHP file, you can declare functions/classes anywhere and call them anywhere (within that file), order does not matter.

As for includes, you must include the file BEFORE you attempt to use a declared function/class within that file.

blocks|key|959667|text|是的，它确实很重要，当涉及到大量的类时，它可能会导致问题。当您的生产脚本需要包含40或50个类时，使用自动加载是不可行的，如果您的应用程序是根据最佳OOP实践正确设计的，并且您需要处理表单等，则始终是这种情况。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|959668|让我解释一下为什么顺序很重要。如果使用自动加载器，则每次找到关键字extends时，都会尝试自动加载类。因此，如果您在定义要扩展的类之前进行扩展，它将触发一个自动加载事件。|959669|在开发应用程序时，请使用自定义的自动加载器。使定制自动加载器提供有关计时和所用内存的信息。它会一个接一个地加载所有的类文件，这样做会浪费很多时间。当您的应用程序完成时，您可以通过将许多相关类集中到一个文件中来进行优化。例如，我的form类在class.form.php中，它不只是加载form类。它加载另外50个与表单相关的类。所以我把所有东西都放在一个文件中，当我创建一个新的form()时，自动加载器加载class.form.php，其中包括表单通常需要的其他类(form_checkbox、form_input等)，所以当需要它们时，它们不是自动加载器，因为它们已经定义好了。|959670|您可以创建一个PHP脚本，该脚本将递归、解析依赖项并对单个类文件中的所有类进行排序(使用我的示例中的class.form.php)，以便它们都具有在找到扩展关键字(触发自动加载)之前定义的父类。我在合并后的文件上运行php+-w，该文件剥离了注释和空格。它将我的表单类从80K减少到18K。每当我使用表单时，我都会创建一个新的form()，它会加载18K的与表单相关的类，这并不过分。|959671|最初，我使用linux命令cat，但它不起作用。您需要一个更智能的脚本来解析每个扩展类的父类，并正确地对包含许多相关类的文件中的类进行排序。|959672|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|M|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|N|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|O|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|P|8|@]|9|@]|A|$]]|$1|J|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|K|$]]

Yes it does matter and when a large number of classes are involved, it can cause problems. Using autoloading is not feasible when your production scripts needs to include 40 or 50 classes, which is always the case if your application is properly designed in accordance with best OOP practices, and you need to deal with forms etc...

Let me explain why the order matters. If you use an autoloader, every time the keyword extends is found, there is an attempt to autoload a class. So if you extend before the class being extended has been defined, it will trigger an autoload event. 

When you develop your application, use a custom autoloader. Make that custom autoloader give you information about timing and memory used. It will load all class files one by one and waste a lot of time doing so. When your application is finished, you can optimize by concentrating many related classes into one file. For example, my form class is in class.form.php and it does not just load the form class. It loads another 50 classes related to forms. So I have everything in one file and when I create a new form(), the autoloader loads class.form.php which include the other classes that a form usually need (form_checkbox, form_input and so on) so when they are needed, they are not autoloader because they are already defined.

You can create a PHP script that will recurse, resolving dependencies and order all your classes within the single class file (class.form.php using my example) so that they all have the parent class defined before the extends keyword (which triggers autoloading) is found. I run php -w on the concatenated file which strips comments and spaces. It has reduced my form classes from 80K to 18K. Whenever I use a form, I create a new form() and it loads 18Ks worth of form-related classes, which is not excessive. 

Initially I used the linux command cat but it does not work. You need a smarter script that can resolve the parent of each extended class and properly order classes in the file that contains many related classes.

If I have several classes in different php files that I'm including into a single file, and some of these classes have dependencies on other classes, does the order in which they are included matter? Or, is simply including them (in any order) before they are used all that matters?

Does the order of class definition matter in PHP?

如果我在不同的php文件中有几个类，并将它们包含到一个文件中，并且这些类中的一些类依赖于其他类，那么它们被包含的顺序重要吗？或者，在使用它们之前简单地包含它们(以任何顺序)都很重要吗？

问PHP中类定义的顺序重要吗？
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