评价'不(假和真)'

Question

我遇到了这个例子("使用Python破解秘密密码",第135页),我很困惑:

not (False and True)

该示例表明它评估为False,但我不明白为什么.如果括号修改优先级,那么我们肯定正在评估:

not (False)

哪个评估True,不是吗？或者我错过了什么？

// output functions are configurable.  This one just appends some text
// to a pre element.
function outf(text) {
  var mypre = document.getElementById("output");
  mypre.innerHTML = mypre.innerHTML + text;
}

function builtinRead(x) {
  if (Sk.builtinFiles === undefined || Sk.builtinFiles["files"][x] === undefined)
    throw "File not found: '" + x + "'";
  return Sk.builtinFiles["files"][x];
}

// Here's everything you need to run a python program in skulpt
// grab the code from your textarea
// get a reference to your pre element for output
// configure the output function
// call Sk.importMainWithBody()
function runit() {
  var prog = document.getElementById("yourcode").value;
  var mypre = document.getElementById("output");
  mypre.innerHTML = '';
  Sk.pre = "output";
  Sk.configure({
    output: outf,
    read: builtinRead
  });
  (Sk.TurtleGraphics || (Sk.TurtleGraphics = {})).target = 'mycanvas';
  var myPromise = Sk.misceval.asyncToPromise(function() {
    return Sk.importMainWithBody("<stdin>", false, prog, true);
  });
  myPromise.then(function(mod) {
      console.log('success');
    },
    function(err) {
      console.log(err.toString());
    });
}

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.9.0/jquery.min.js" type="text/javascript"></script>
<script src="http://www.skulpt.org/static/skulpt.min.js" type="text/javascript"></script>
<script src="http://www.skulpt.org/static/skulpt-stdlib.js" type="text/javascript"></script>

<h3>Try This</h3> 
<form>
  <textarea id="yourcode" cols="40" rows="10">print(not (False and True))
  </textarea>
  <br />
  <button type="button" onclick="runit()">Run</button>
</form>
<pre id="output"></pre> 
<!-- If you want turtle graphics include a canvas -->
<div id="mycanvas"></div>

Answer 1

这实际上包含在勘误表中:

第135页,交互式shell应如下所示:

>>> not False and False # not False evaluates first 
True 
>>> not (False and False) # (False and False) evaluates first 
False 

(感谢Omer Chohan)

它已在本章的在线版本中得到纠正,但不在PDF中.