A few lines of code are not too understandable. Please help analyze this code from a small segment of PHPcode/** + ------------------------------------------------------------ a few lines of code are not too understandable.
This code is taken from a small clip in the ThinkPHP framework.
PHP code
/** + ---------------------- * Obtain the static method of the object instance supporting calling class + ---------------------- * @ param string $ class object class name * @ param string $ method class static method name + ----------------------* @ return object + ---------------------- */static public function instance ($ class, $ method = '') {$ identify = $ class. $ method; if (! Isset (self ::$ _ instance [$ identify]) {// The self: This row is not too explicit. if (class_exists ($ class )) {// This is to judge if the class exists? $ O = new $ class (); if (! Empty ($ method) & method_exists ($ o, $ method) self: $ _ instance [$ identify] = call_user_func_array (array (& $ o, $ method )); // How to explain this line? Else self: $ _ instance [$ identify] = $ o; // How to explain this line? } Else halt (L ('_ CLASS_NOT_EXIST _'). ':'. $ class); // halt has never seen this thing ...... } Return self: $ _ instance [$ identify];}
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Assume that the class name is Core. php.
Core. php has a static attribute.
Public static $ _ instance // note that this attribute is an array.
This function provides two functions:
1. factory class: used to create objects. If the method is Null, a class is returned.
2. execute methods of a class. If the method is not empty, the result of method execution is returned.
If (! Isset (self: $ _ instance [$ identify]) {// use Self to reference static methods. Self: indicates the current class itself, not the current object.
If (class_exists ($ class) {// This is to determine whether this class file exists, of course, this is the encapsulated method. You can understand File_exist (filename) in the IO operation ).
Self: $ _ instance [$ identify] = call_user_func_array (array (& $ o, $ method); // This actually reflects the method that calls a class.
Self: $ _ instance [$ identify] = $ o; // if the method name is empty, put the object in the array.
Halt (L ('_ CLASS_NOT_EXIST _'). ':'. $ class); // halt indicates stop. It seems that the compilation is stopped.
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Okayu has already explained this.
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This function provides two functions:
1. factory class: used to create objects. If the method is Null, a class is returned.
2. execute methods of a class. If the method is not empty, the result of method execution is returned.
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Code reading should focus on the overall situation.
The explanation is really good. Also followed by learning.
From large to small.
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This is a registration class! It cannot be a workshop! Limitations
1) If the class is not initialized, the class will be initialized and there will be an array of class properties; if the class has been initialized, the class will be returned. (The Workshop class should return a new instance each time;
2) If there is a method, but the result of calling the method is returned. (Parameters cannot be passed. any method is called instead of static methods)
Call_user_func_array (array (& $ o, $ method) here & I do not know if it is necessary.
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& $ O in php seems to be $ o
Similar to the pointer of C, but different!
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Discussion
This is a registration class! It cannot be a workshop! Limitations
1) If the class is not initialized, the class will be initialized and there will be an array of class properties; if the class has been initialized, the class will be returned. (The Workshop class should return a new instance each time;
2) If there is a method, but the result of calling the method is returned. (Parameters cannot be passed. any method is called instead of static methods)
Call_user_func_array (array (& $ o, $ method ......
