import requests
r = requests.get('http://www.jerrylsu.net/articles/2020/programming-Python-Decorator.html')
r.encoding
'ISO-8859-1'
r.encoding = 'utf-8'
r.text
'<!DOCTYPE html>\n<html lang="en" prefix="og: http://ogp.me/ns# fb: https://www.facebook.com/2008/fbml">\n<head>\n <title>Python Decorator - Jerrylsu.net</title>\n <!-- Using the latest rendering mode for IE -->\n <meta http-equiv="X-UA-Compatible" content="IE=edge">\n <meta charset="utf-8">\n <meta name="viewport" content="width=device-width, initial-scale=1.0">\n\n\n <link href="/jerry.jpg" rel="icon">\n\n<link rel="canonical" href="/articles/2020/programming-Python-Decorator.html">\n\n <meta name="author" content="Jerry Su" />\n <meta name="keywords" content="Python" />\n <meta name="description" content="0. 装饰器¶装饰器：接收一个函数（被装饰的函数）对象，返回一个函数（已装饰的函数）对象。动态的给一个对象添加额外职责，即装饰器设计模式。 装饰器的典型行为：把被装饰的函数替换为新函数，二者接收的参数相同，并返回被装饰函数本该的返回值，同时增加一些额外操作。 func = factorial, factorial = clocked clock是装饰器 factorial是被装饰函数 clocked是被装饰后的函数 factorial作为func参数传递给装饰器clock，装饰器clock返回clocked函数并复制给factorial。func是clocked的自由变量，两者构成闭包。 当调用函数factorial时，实际上调用函数locked，而locked函数中func则为被装饰的函数factorial。" />\n\n <meta property="og:site_name" content="Jerrylsu.net" />\n <meta property="og:type" content="article"/>\n <meta property="og:title" content="Python Decorator"/>\n <meta property="og:url" content="/articles/2020/programming-Python-Decorator.html"/>\n <meta property="og:description" content="0. 装饰器¶装饰器：接收一个函数（被装饰的函数）对象，返回一个函数（已装饰的函数）对象。动态的给一个对象添加额外职责，即装饰器设计模式。 装饰器的典型行为：把被装饰的函数替换为新函数，二者接收的参数相同，并返回被装饰函数本该的返回值，同时增加一些额外操作。 func = factorial, factorial = clocked clock是装饰器 factorial是被装饰函数 clocked是被装饰后的函数 factorial作为func参数传递给装饰器clock，装饰器clock返回clocked函数并复制给factorial。func是clocked的自由变量，两者构成闭包。 当调用函数factorial时，实际上调用函数locked，而locked函数中func则为被装饰的函数factorial。"/>\n <meta property="article:published_time" content="2020-12-20" />\n <meta property="article:section" content="Programming" />\n <meta property="article:tag" content="Python" />\n <meta property="article:author" content="Jerry Su" />\n\n\n\n <!-- Bootstrap -->\n <link rel="stylesheet" href="/theme/css/bootstrap.min.css" type="text/css"/>\n <link 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<li class="active">Python Decorator</li>\n </ol>\n <section id="content">\n <article>\n <header class="page-header">\n <h1>\n <a href="/articles/2020/programming-Python-Decorator.html"\n rel="bookmark"\n title="Permalink to Python Decorator">\n Python Decorator\n </a>\n </h1>\n </header>\n <div class="entry-content">\n <div class="panel">\n <div class="panel-body">\n<footer class="post-info">\n <span class="label label-default">Date</span>\n <span class="published">\n <i class="fa fa-calendar"></i><time datetime="2020-12-20T10:17:17+08:00"> 2020-12-20 Sun</time>\n </span>\n\n\n\n\n\n<span class="label label-default">Tags</span>\n\t<a href="/tags/python.html">Python</a>\n \n</footer><!-- /.post-info --> </div>\n </div>\n <style type="text/css">/*!\n*\n* IPython notebook\n*\n*/\n/* CSS font colors for translated ANSI escape sequences */\n/* The color values are a mix of\n http://www.xcolors.net/dl/baskerville-ivorylight and\n http://www.xcolors.net/dl/euphrasia */\n.ansi-black-fg {\n 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240, 240, 0.5);\n}\ndiv.output_prompt {\n color: #D84315;\n}\n/* This class is the outer container of all output sections. */\ndiv.output_area {\n padding: 0px;\n page-break-inside: avoid;\n /* Old browsers */\n display: -webkit-box;\n -webkit-box-orient: horizontal;\n -webkit-box-align: stretch;\n display: -moz-box;\n -moz-box-orient: horizontal;\n -moz-box-align: stretch;\n display: box;\n box-orient: horizontal;\n box-align: stretch;\n /* Modern browsers */\n display: flex;\n flex-direction: row;\n align-items: stretch;\n}\ndiv.output_area .MathJax_Display {\n text-align: left !important;\n}\ndiv.output_area \ndiv.output_area \ndiv.output_area img,\ndiv.output_area svg {\n max-width: 100%;\n height: auto;\n}\ndiv.output_area img.unconfined,\ndiv.output_area svg.unconfined {\n max-width: none;\n}\ndiv.output_area .mglyph > img {\n max-width: none;\n}\n/* This is needed to protect the pre formating from global settings such\n as that of bootstrap */\n.output {\n /* Old browsers */\n 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.highlight pre .mh { color: #666666 } /* Literal.Number.Hex */\n .highlight pre .mi { color: #666666 } /* Literal.Number.Integer */\n .highlight pre .mo { color: #666666 } /* Literal.Number.Oct */\n .highlight pre .sa { color: #BA2121 } /* Literal.String.Affix */\n .highlight pre .sb { color: #BA2121 } /* Literal.String.Backtick */\n .highlight pre .sc { color: #BA2121 } /* Literal.String.Char */\n .highlight pre .dl { color: #BA2121 } /* Literal.String.Delimiter */\n .highlight pre .sd { color: #BA2121; font-style: italic } /* Literal.String.Doc */\n .highlight pre .s2 { color: #BA2121 } /* Literal.String.Double */\n .highlight pre .se { color: #BB6622; font-weight: bold } /* Literal.String.Escape */\n .highlight pre .sh { color: #BA2121 } /* Literal.String.Heredoc */\n .highlight pre .si { color: #BB6688; font-weight: bold } /* Literal.String.Interpol */\n .highlight pre .sx { color: #008000 } /* Literal.String.Other */\n .highlight pre .sr { color: #BB6688 } /* Literal.String.Regex */\n .highlight pre .s1 { color: #BA2121 } /* Literal.String.Single */\n .highlight pre .ss { color: #19177C } /* Literal.String.Symbol */\n .highlight pre .bp { color: #008000 } /* Name.Builtin.Pseudo */\n .highlight pre .fm { color: #0000FF } /* Name.Function.Magic */\n .highlight pre .vc { color: #19177C } /* Name.Variable.Class */\n .highlight pre .vg { color: #19177C } /* Name.Variable.Global */\n .highlight pre .vi { color: #19177C } /* Name.Variable.Instance */\n .highlight pre .vm { color: #19177C } /* Name.Variable.Magic */\n .highlight pre .il { color: #666666 } /* Literal.Number.Integer.Long */</style><body><div class="cell border-box-sizing text_cell rendered"><div class="prompt input_prompt">\n</div><div class="inner_cell">\n<div class="text_cell_render border-box-sizing rendered_html">\n<h2 id="0.-装饰器">0. 装饰器<a class="anchor-link" href="#0.-装饰器">¶</a></h2><p>装饰器：接收一个函数（被装饰的函数）对象，返回一个函数（已装饰的函数）对象。动态的给一个对象添加额外职责，即装饰器设计模式。</p>\n<p>装饰器的典型行为：把被装饰的函数替换为新函数，二者接收的参数相同，并返回被装饰函数本该的返回值，同时增加一些额外操作。</p>\n<p><strong>func = factorial, factorial = clocked</strong></p>\n<p>clock是装饰器</p>\n<p>factorial是被装饰函数</p>\n<p>clocked是被装饰后的函数</p>\n<p>factorial作为func参数传递给装饰器clock，装饰器clock返回clocked函数并复制给factorial。func是clocked的自由变量，两者构成闭包。</p>\n<p>当调用函数factorial时，实际上调用函数locked，而locked函数中func则为被装饰的函数factorial。</p>\n\n</div>\n</div>\n</div>\n<div class="cell border-box-sizing code_cell rendered">\n<div class="input">\n<div class="prompt input_prompt">In [40]:</div>\n<div class="inner_cell">\n <div class="input_area">\n<div class=" highlight hl-ipython3"><pre><span></span><span class="c1"># 实现一个简单的装饰器：调用被装饰的函数时，打印被调用函数的运行时间，传入参数和输出结果。</span>\n\n<span class="kn">import</span> <span class="nn">time</span>\n\n<span class="k">def</span> <span class="nf">clock</span><span class="p">(</span><span class="n">func</span><span class="p">):</span>\n <span class="k">def</span> <span class="nf">clocked</span><span class="p">(</span><span class="o">*</span><span class="n">args</span><span class="p">):</span>\n <span class="n">start</span> <span class="o">=</span> <span class="n">time</span><span class="o">.</span><span class="n">time</span><span class="p">()</span>\n <span class="n">result</span> <span class="o">=</span> <span class="n">func</span><span class="p">(</span><span class="o">*</span><span class="n">args</span><span class="p">)</span>\n <span class="n">end</span> <span class="o">=</span> <span class="n">time</span><span class="o">.</span><span class="n">time</span><span class="p">()</span> <span class="o">-</span> <span class="n">start</span>\n <span class="n">arg_str</span> <span class="o">=</span> <span class="s1">''</span><span class="o">.</span><span class="n">join</span><span class="p">([</span><span class="nb">repr</span><span class="p">(</span><span class="n">arg</span><span class="p">)</span> <span class="k">for</span> <span class="n">arg</span> <span class="ow">in</span> <span class="n">args</span><span class="p">])</span>\n <span class="nb">print</span><span class="p">(</span><span class="sa">f</span><span class="s1">'time: </span><span class="si">{</span><span class="n">end</span><span class="si">}</span><span class="s1">, args: </span><span class="si">{</span><span class="n">arg_str</span><span class="si">}</span><span class="s1">, result: </span><span class="si">{</span><span class="n">result</span><span class="si">}</span><span class="s1">'</span><span class="p">)</span>\n <span class="k">return</span> <span class="n">result</span>\n <span class="k">return</span> <span class="n">clocked</span>\n \n<span class="nd">@clock</span>\n<span class="k">def</span> <span class="nf">factorial</span><span class="p">(</span><span class="n">n</span><span class="p">):</span>\n <span class="k">return</span> <span class="mi">1</span> <span class="k">if</span> <span class="n">n</span> <span class="o"><</span> <span class="mi">2</span> <span class="k">else</span> <span class="n">n</span> <span class="o">*</span> <span class="n">factorial</span><span class="p">(</span><span class="n">n</span> <span class="o">-</span> <span class="mi">1</span><span class="p">)</span>\n</pre></div>\n\n </div>\n</div>\n</div>\n\n</div>\n<div class="cell border-box-sizing code_cell rendered">\n<div class="input">\n<div class="prompt input_prompt">In [39]:</div>\n<div class="inner_cell">\n <div class="input_area">\n<div class=" highlight hl-ipython3"><pre><span></span><span class="n">factorial</span><span class="p">(</span><span class="mi">6</span><span class="p">)</span>\n</pre></div>\n\n </div>\n</div>\n</div>\n\n<div class="output_wrapper">\n<div class="output">\n\n\n<div class="output_area">\n\n <div class="prompt"></div>\n\n\n<div class="output_subarea output_stream output_stdout output_text">\n<pre>time: 7.152557373046875e-07, args: 1, result: 1\ntime: 0.0006625652313232422, args: 2, result: 2\ntime: 0.0007753372192382812, args: 3, result: 6\ntime: 0.0008685588836669922, args: 4, result: 24\ntime: 0.000957489013671875, args: 5, result: 120\ntime: 0.0010552406311035156, args: 6, result: 720\n</pre>\n</div>\n</div>\n\n<div class="output_area">\n\n <div class="prompt output_prompt">Out[39]:</div>\n\n\n\n\n<div class="output_text output_subarea output_execute_result">\n<pre>720</pre>\n</div>\n\n</div>\n\n</div>\n</div>\n\n</div>\n<div class="cell border-box-sizing code_cell rendered">\n<div class="input">\n<div class="prompt input_prompt">In [42]:</div>\n<div class="inner_cell">\n <div class="input_area">\n<div class=" highlight hl-ipython3"><pre><span></span><span class="n">factorial</span><span class="o">.</span><span class="vm">__name__</span> <span class="c1"># 可见factorial是函数locked的引用， 调用factorial(n)即调用locked(n)</span>\n</pre></div>\n\n </div>\n</div>\n</div>\n\n<div class="output_wrapper">\n<div class="output">\n\n\n<div class="output_area">\n\n <div class="prompt output_prompt">Out[42]:</div>\n\n\n\n\n<div class="output_text output_subarea output_execute_result">\n<pre>'clocked'</pre>\n</div>\n\n</div>\n\n</div>\n</div>\n\n</div>\n<div class="cell border-box-sizing text_cell rendered"><div class="prompt input_prompt">\n</div><div class="inner_cell">\n<div class="text_cell_render border-box-sizing rendered_html">\n<h2 id="1.-装饰器何时运行？">1. 装饰器何时运行？<a class="anchor-link" href="#1.-装饰器何时运行？">¶</a></h2><p>导入时与运行时：函数装饰器在<strong>导入模块时立即执行</strong>，而被装饰器装饰的函数，只有程序运行时显式调用时才执行。</p>\n<p>装饰器在实际工程中：</p>\n<ul>\n<li><p>通常，装饰器在一个py模块中定义，应用到其他py模块的函数上。</p>\n</li>\n<li><p>通常，装饰器内部绘重新定义一个函数，将其返回。而非作为装饰器参数的函数。</p>\n</li>\n</ul>\n\n</div>\n</div>\n</div>\n<div class="cell border-box-sizing code_cell rendered">\n<div class="input">\n<div class="prompt input_prompt">In [1]:</div>\n<div class="inner_cell">\n <div class="input_area">\n<div class=" highlight hl-ipython3"><pre><span></span><span class="n">registry</span> <span class="o">=</span> <span class="p">[]</span>\n\n<span class="k">def</span> <span class="nf">register</span><span class="p">(</span><span class="n">func</span><span class="p">):</span>\n <span class="nb">print</span><span class="p">(</span><span class="sa">f</span><span class="s1">'running register </span><span class="si">{</span><span class="n">func</span><span class="si">}</span><span class="s1">'</span><span class="p">)</span>\n <span class="n">registry</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="n">func</span><span class="p">)</span>\n <span class="k">return</span> <span class="n">func</span>\n\n<span class="nd">@register</span>\n<span class="k">def</span> <span class="nf">func1</span><span class="p">():</span>\n <span class="nb">print</span><span class="p">(</span><span class="s1">'running func1'</span><span class="p">)</span>\n\n<span class="nd">@register</span>\n<span class="k">def</span> <span class="nf">func2</span><span class="p">():</span>\n <span class="nb">print</span><span class="p">(</span><span class="s1">'running func2'</span><span class="p">)</span>\n \n<span class="k">def</span> <span class="nf">func3</span><span class="p">():</span>\n <span class="nb">print</span><span class="p">(</span><span class="s1">'running fucn3'</span><span class="p">)</span>\n\n<span class="k">def</span> <span class="nf">main</span><span class="p">():</span>\n <span class="nb">print</span><span class="p">(</span><span class="n">registry</span><span class="p">)</span>\n <span class="n">func1</span><span class="p">()</span>\n <span class="n">func2</span><span class="p">()</span>\n <span class="n">func3</span><span class="p">()</span>\n</pre></div>\n\n </div>\n</div>\n</div>\n\n<div class="output_wrapper">\n<div class="output">\n\n\n<div class="output_area">\n\n <div class="prompt"></div>\n\n\n<div class="output_subarea output_stream output_stdout output_text">\n<pre>running register <function func1 at 0x7fac1e2b6040>\nrunning register <function func2 at 0x7fac1e2b61f0>\n</pre>\n</div>\n</div>\n\n</div>\n</div>\n\n</div>\n<div class="cell border-box-sizing code_cell rendered">\n<div class="input">\n<div class="prompt input_prompt">In [2]:</div>\n<div class="inner_cell">\n <div class="input_area">\n<div class=" highlight hl-ipython3"><pre><span></span><span class="n">registry</span>\n</pre></div>\n\n </div>\n</div>\n</div>\n\n<div class="output_wrapper">\n<div class="output">\n\n\n<div class="output_area">\n\n <div class="prompt output_prompt">Out[2]:</div>\n\n\n\n\n<div class="output_text output_subarea output_execute_result">\n<pre>[<function __main__.func1()>, <function __main__.func2()>]</pre>\n</div>\n\n</div>\n\n</div>\n</div>\n\n</div>\n<div class="cell border-box-sizing code_cell rendered">\n<div class="input">\n<div class="prompt input_prompt">In [4]:</div>\n<div class="inner_cell">\n <div class="input_area">\n<div class=" highlight hl-ipython3"><pre><span></span><span class="n">main</span><span class="p">()</span>\n</pre></div>\n\n </div>\n</div>\n</div>\n\n<div class="output_wrapper">\n<div class="output">\n\n\n<div class="output_area">\n\n <div class="prompt"></div>\n\n\n<div class="output_subarea output_stream output_stdout output_text">\n<pre>[<function func1 at 0x7fac1e2b6040>, <function func2 at 0x7fac1e2b61f0>]\nrunning func1\nrunning func2\nrunning fucn3\n</pre>\n</div>\n</div>\n\n</div>\n</div>\n\n</div>\n<div class="cell border-box-sizing text_cell rendered"><div class="prompt input_prompt">\n</div><div class="inner_cell">\n<div class="text_cell_render border-box-sizing rendered_html">\n<h2 id="2.-闭包">2. 闭包<a class="anchor-link" href="#2.-闭包">¶</a></h2><p>多数装饰器会修改被装饰的函数。通常是在装饰器<strong>内部重新定义一个函数</strong>，将其返回，用来替换被装饰的函数。装饰器内部定义函数几乎都需要<strong>闭包</strong>。</p>\n\n</div>\n</div>\n</div>\n<div class="cell border-box-sizing code_cell rendered">\n<div class="input">\n<div class="prompt input_prompt">In [ ]:</div>\n<div class="inner_cell">\n <div class="input_area">\n<div class=" highlight hl-ipython3"><pre><span></span><span class="c1"># 设计某商品收盘均价。注：实时增加新价</span>\n\n<span class="c1"># 类写法</span>\n<span class="k">class</span> <span class="nc">Averager</span><span class="p">():</span>\n <span class="k">def</span> <span class="fm">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>\n <span class="bp">self</span><span class="o">.</span><span class="n">series</span> <span class="o">=</span> <span class="p">[]</span>\n \n <span class="k">def</span> <span class="fm">__call__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">price</span><span class="p">):</span> <span class="c1"># 可调用对象</span>\n <span class="bp">self</span><span class="o">.</span><span class="n">series</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="n">price</span><span class="p">)</span>\n <span class="nb">print</span><span class="p">(</span><span class="nb">sum</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">series</span><span class="p">)</span> <span class="o">/</span> <span class="nb">len</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">series</span><span class="p">))</span>\n \n<span class="n">avg</span> <span class="o">=</span> <span class="n">Averager</span><span class="p">()</span>\n<span class="n">avg</span><span class="p">(</span><span class="mi">10</span><span class="p">)</span> <span class="c1"># 可调用对象 __call__()</span>\n<span class="n">avg</span><span class="p">(</span><span class="mi">11</span><span class="p">)</span>\n</pre></div>\n\n </div>\n</div>\n</div>\n\n</div>\n<div class="cell border-box-sizing code_cell rendered">\n<div class="input">\n<div class="prompt input_prompt">In [14]:</div>\n<div class="inner_cell">\n <div class="input_area">\n<div class=" highlight hl-ipython3"><pre><span></span><span class="c1"># 函数式写法，高阶函数</span>\n\n<span class="k">def</span> <span class="nf">make_averager</span><span class="p">():</span>\n <span class="n">series</span> <span class="o">=</span> <span class="p">[]</span>\n \n <span class="k">def</span> <span class="nf">averager</span><span class="p">(</span><span class="n">price</span><span class="p">):</span>\n <span class="n">series</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="n">price</span><span class="p">)</span>\n <span class="nb">print</span><span class="p">(</span><span class="nb">sum</span><span class="p">(</span><span class="n">series</span><span class="p">)</span> <span class="o">/</span> <span class="nb">len</span><span class="p">(</span><span class="n">series</span><span class="p">))</span>\n \n <span class="k">return</span> <span class="n">averager</span>\n\n<span class="n">avg</span> <span class="o">=</span> <span class="n">make_averager</span><span class="p">()</span>\n<span class="n">avg</span><span class="p">(</span><span class="mi">10</span><span class="p">)</span>\n<span class="n">avg</span><span class="p">(</span><span class="mi">11</span><span class="p">)</span>\n</pre></div>\n\n </div>\n</div>\n</div>\n\n<div class="output_wrapper">\n<div class="output">\n\n\n<div class="output_area">\n\n <div class="prompt"></div>\n\n\n<div class="output_subarea output_stream output_stdout output_text">\n<pre>10.0\n10.5\n</pre>\n</div>\n</div>\n\n</div>\n</div>\n\n</div>\n<div class="cell border-box-sizing text_cell rendered"><div class="prompt input_prompt">\n</div><div class="inner_cell">\n<div class="text_cell_render border-box-sizing rendered_html">\n<p>类写法和函数式写法：</p>\n<ul>\n<li><p>共同之处：通过实例化类Averager()和调用make_averager()都会得到一个<strong>可调用对象</strong>。</p>\n</li>\n<li><p>不同之处：如何存历史值price？类self.series，而函数式则存在series中。</p>\n</li>\n</ul>\n<p>而series作为函数make_averager局部变量，在函数返回时局部变量应该销毁。而series相对于make_averager的内部函数averager称为自由变量。</p>\n\n<pre><code> series = []\n\n def averager(price):\n series.append(price)\n print(sum(series) / len(series))</code></pre>\n<p>这个代码块称为闭包。闭包是一种函数，它会保留定义函数时存在的自由变量绑定，即使像make_averager函数返回作用域不存在了，averager函数仍然保留使用这些自由变量绑定。</p>\n<p><strong>重点：只有在嵌套函数中的函数，才可能处理不在全局作用域中的外部变量，相对该函数称为自由变量。而该函数与自由变量称为闭包。</strong></p>\n\n</div>\n</div>\n</div>\n<div class="cell border-box-sizing text_cell rendered"><div class="prompt input_prompt">\n</div><div class="inner_cell">\n<div class="text_cell_render border-box-sizing rendered_html">\n<h2 id="3.-关键字nonlocal">3. 关键字nonlocal<a class="anchor-link" href="#3.-关键字nonlocal">¶</a></h2>\n</div>\n</div>\n</div>\n \n\n</body>\n<script type="text/javascript">if (!document.getElementById(\'mathjaxscript_pelican_#%@#$@#\')) {\n var mathjaxscript = document.createElement(\'script\');\n mathjaxscript.id = \'mathjaxscript_pelican_#%@#$@#\';\n mathjaxscript.type = \'text/javascript\';\n mathjaxscript.src = \'//cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/MathJax.js?config=TeX-AMS-MML_HTMLorMML\';\n 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