Meta-Programming in PHP

Read the definition or confused.

Can you explain what is meta-programming in PHP (Ruby) in a popular language or an example?

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Read the definition or confused.

Can you explain what is meta-programming in PHP (Ruby) in a popular language or an example?

For example:
"Programming" is equivalent to I made a machine, this machine can help me sweep the floor (sweeping machine).
"Meta-programming" is that I made a machine that can make "sweeping machine". This machine can produce a lot of sweeping machine, it produces the sweeping opportunity to help me sweep the floor.

" meta-programming ", also called Metaprogramming , its essence is still "programming", and more than the simple "programming" is more than the ability to dynamically generate executable code.

There are a number of ways to generate code. such as the C language preprocessing macros, closures/objects and some specific structures (in Lisp macros and C + + templates) and so on ( dynamic language can be eval a direct string, although it can also be considered "dynamically generated code", but the overall should be attributed to dynamic language characteristics ).

Metaprogramming is not a useless thing to play with or a bunch of Gao Tang. Template meta-programming is the essence of C + +, and the base of C + + standard library, the well-known Ruby project is almost everywhere meta programming, and Ruby has become more expressive and implemented because of metaprogramming.

Like what:

//C++ 模板template
  
   
    
       //对任意类型T进行声明和定义class vector{    ...};vector
   
    
     
     vec;  //编译期自动生成vector
    
     
      
     类型的各项代码
    
     
   
    
  
   

and Ruby Meta programming

#Ruby中一个简单的类定义class D  def a    'a'  end  def b    'b'  end  def c    'c'  endend#=> 下面是等价代码：D2 = Class.new do    [:a,:b,:c].each do | sym |      #在each中动态生成三个类方法      define_method sym, { sym.to_s }    end  end

The simple use of meta-programming can simplify the work and, to a certain extent, make the code more expressive. The depth of meta-programming can even greatly improve the efficiency of work, but often pay the price of it needs to have in-depth understanding and practice.

In addition, PHP's dynamic characteristics are often criticized and abused, but if you can make some good packaging and design, there are some good meta-programming features.

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