我想在F＃中创建一个bitflags枚举，使用bitshift运算符来提高可读性：例如
[<Flags>]
type DaysOfWeek =
| Monday = 1 <<< 0
| Tuesday = 1 <<< 1
| Wednesday = 1 <<< 2
| Thursday = 1 <<< 3
| Friday = 1 <<< 4
| Saturday = 1 <<< 5
| Sunday = 1 <<< 6
然而，F＃编译器不喜欢这个。它在成员定义中说＆＃34;意外的中缀运算符＆＃34;。
我希望这种方法超过两种手动权力。有没有办法说服编译器我不是邪恶的？
答案 0 :(得分：8)
这不完全是您所要求的，但您可以使用0b前缀来编写二进制长手，例如：
[<Flags>]
type DaysOfWeek =
| Monday = 0b0000001
| Tuesday = 0b0000010
| Wednesday = 0b0000100
| Thursday = 0b0001000
| Friday = 0b0010000
| Saturday = 0b0100000
| Sunday = 0b1000000
答案 1 :(得分：3)
将案例与值分开的替代方法，更详细但更灵活：
<?php
/**
* Created by PhpStorm.
* User: Taz
* Date: 9/29/2016
* Time: 5:37 PM
*/
?>
<html>
<head>
<title>Ajax Image Upload Using PHP and jQuery</title>
<link rel="stylesheet" href="style.css" />
<link href='http://fonts.googleapis.com/css?family=Roboto+Condensed|Open+Sans+Condensed:300' rel='stylesheet' type='text/css'>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<script type="text/javascript">
$(document).ready(function (e) {
$("#uploadimage").on('submit',(function(e) {
e.preventDefault();
$("#message").empty();
$('#loading').show();
$.ajax({
url: "ajax_upload_image_submit.php", // Url to which the request is send
type: "POST", // Type of request to be send, called as method
data: new FormData(this), // Data sent to server, a set of key/value pairs (i.e. form fields and values)
contentType: false, // The content type used when sending data to the server.
cache: false, // To unable request pages to be cached
processData:false, // To send DOMDocument or non processed data file it is set to false
success: function(data) // A function to be called if request succeeds
{
$('#loading').hide();
$("#message").html(data);
}
});
}));
// Function to preview image after validation
$(function() {
$("#file").change(function() {
$("#message").empty(); // To remove the previous error message
var file = this.files[0];
var imagefile = file.type;
var match= ["image/jpeg","image/png","image/jpg"];
if(!((imagefile==match[0]) || (imagefile==match[1]) || (imagefile==match[2])))
{
$('#previewing').attr('src','noimage.png');
$("#message").html("<p id='error'>Please Select A valid Image File</p>"+"<h4>Note</h4>"+"<span id='error_message'>Only jpeg, jpg and png Images type allowed</span>");
return false;
}
else
{
var reader = new FileReader();
reader.onload = imageIsLoaded;
reader.readAsDataURL(this.files[0]);
}
});
});
function imageIsLoaded(e) {
$("#file").css("color","green");
$('#image_preview').css("display", "block");
$('#previewing').attr('src', e.target.result);
$('#previewing').attr('width', '250px');
$('#previewing').attr('height', '230px');
};
});
</script>
<style>
body {
font-family: 'Roboto Condensed', sans-serif;
}
h1
{
text-align: center;
background-color: #96DAD1;
height: 70px;
color: rgb(95, 89, 89);
margin: 0 0 -29px 0;
padding-top: 14px;
font-size: 35px;
}
.main {
position: absolute;
top: 50px;
left: 20%;
width: 450px;
height:530px;
border: 2px solid gray;
}
.main label{
color: rgba(0, 0, 0, 0.71);
margin-left: 60px;
}
#image_preview{
position: absolute;
font-size: 30px;
top: 100px;
left: 100px;
width: 250px;
height: 230px;
text-align: center;
line-height: 180px;
font-weight: bold;
color: #C0C0C0;
background-color: #FFFFFF;
overflow: auto;
}
#selectImage{
padding: 19px 21px 14px 15px;
position: absolute;
bottom: 0px;
width: 414px;
background-color: #EDFCFF;
}
.submit{
font-size: 16px;
background: linear-gradient(#ffbc00 5%, #ffdd7f 100%);
border: 1px solid #e5a900;
color: #4E4D4B;
font-weight: bold;
cursor: pointer;
width: 300px;
border-radius: 5px;
padding: 10px 0;
outline: none;
margin-top: 20px;
margin-left: 15%;
}
.submit:hover{
background: linear-gradient(#ffdd7f 5%, #ffbc00 100%);
}
#file {
color: red;
padding: 5px;
border: 5px solid #96DAD1;
background-color: #96DAD1;
margin-top: 10px;
margin-left: 15%;
width: 72%;
}
#message{
position:absolute;
top:120px;
left:815px;
}
#success
{
color:green;
}
#invalid
{
color:red;
}
#line
{
margin-top: 274px;
}
#error
{
color:red;
}
#error_message
{
color:blue;
}
#loading
{
display:none;
position:absolute;
top:50px;
left:850px;
font-size:25px;
}
</style>
</head>
<body>
<div class="main">
<h1>Facebook Update</h1><br/>
<hr>
<form id="uploadimage" action="" method="post" enctype="multipart/form-data">
<div id="image_preview"><img id="previewing" src="noimage.png" width="250" height="230" /></div>
<hr id="line">
<div id="selectImage">
<label>Select Your Image</label><br/>
<input type="file" name="file" id="file" required />
<label>FB Link</label><br/>
<input type="text" name="fb_link" id="fb_link" required />
<label>Show/Hide Status</label><br/>
<select name="show_fb" class="myselect" required>
<option value="">---Select---</option>
<option value="1">Show</option>
<option value="0">Hide</option>
</select>
<input type="submit" value="Upload" class="submit" />
</div>
</form>
</div>
<h4 id='loading' >loading..</h4>
<div id="message"></div>
</body>
</html>
答案 2 :(得分：0)
这是 Dave Fancher 在 The Book of F#
中推荐的方法将 Flags 属性与值为 2 的幂的值一起使用：
open System
[<Flags>]
type DayOfWeek =
| None = 0
| Sunday = 1
| Monday = 2
| Tuesday = 4
| Wednesday = 8
| Thursday = 16
| Friday = 32
| Saturday = 64
Flags 属性不是必需的，但可以明确您的意图。
您现在可以使用按位运算符表示值的组合：
let weekend = DayOfWeek.Saturday ||| DayOfWeek.Sunday