动态修改或生成Java代码

Question

我正在对某些表数据进行多重排序。我想在我的AngularJS网站中动态修改指定排序优先级的代码行。 （我只是在修改数组的结构，因为AngularJS监视绑定数据的更改并将其动态反映在HTML显示中。）

对于多分类，我正在使用thenBy.js。从本质上讲，您创建了一个以firstBy（compareFunctionFunction）开头的变量，然后可以根据需要添加任意数量的thenBy（comparativeFunction）。

我正在根据需要动态添加和删除排序比较器。这是我从简单的两级多重排序开始的地方：

// I want to modify and append to this line
var s = firstBy( (a, b) => a["Status"].localeCompare(b["Status"]) )
  .thenBy( (a, b) => parseFloat(a["#"]) - parseFloat(b["#"]) );
[它最初将根据“状态”属性中的数据对行进行排序，然后对作为ID号的“＃”进行子排序。

我想知道的是如何在上面的行中动态添加更多代码。例如，假设我想添加一个第三级排序，例如在“ Uniquie ID”上。对行进行硬编码，我可以这样：

var s = firstBy( (a, b) => a["Status"].localeCompare(b["Status"]) )
  .thenBy( (a, b) => parseFloat(a["#"]) - parseFloat(b["#"]) )
  .thenBy( (a, b) => parseFloat(a["Unique ID"]) - parseFloat(b["Unique ID"]) );
我只是不确定如何以编程方式将更多的'thenBy（）'方法追加到该行。我应该生成一个字符串并通过eval（）

运行它吗？有没有更好（更安全）的方法？

这里是程序：

self.dataSource = [
    {"#": "1", "Unique ID": "100130", "Name": "Book", "Section": "Paraguay", "Position": "Shelf 1 - Rack 1 - Box 1 - Position 1", "Status": "Available"},
    {"#": "2", "Unique ID": "100131", "Name": "Book", "Section": "Paraguay", "Position": "Shelf 1 - Rack 1 - Box 1 - Position 2", "Status": "Available"},
    {"#": "3", "Unique ID": "100132", "Name": "Book", "Section": "Paraguay", "Position": "Shelf 1 - Rack 1 - Box 1 - Position 3", "Status": "Available"},
    {"#": "4", "Unique ID": "100133", "Name": "Book", "Section": "Paraguay", "Position": "Shelf 1 - Rack 1 - Box 1 - Position 4", "Status": "Available"},
    {"#": "5", "Unique ID": "100134", "Name": "Book", "Section": "Paraguay", "Position": "Shelf 1 - Rack 1 - Box 1 - Position 5", "Status": "Checked Out"},
    {"#": "6", "Unique ID": "100135", "Name": "Book", "Section": "Paraguay", "Position": "Shelf 1 - Rack 1 - Box 1 - Position 6", "Status": "Checked Out"},
    {"#": "7", "Unique ID": "100136", "Name": "Book", "Section": "Paraguay", "Position": "Shelf 1 - Rack 1 - Box 1 - Position 7", "Status": "Checked Out"},
    {"#": "8", "Unique ID": "100137", "Name": "Book", "Section": "Paraguay", "Position": "Shelf 1 - Rack 1 - Box 1 - Position 8", "Status": "Checked Out"},
    {"#": "9", "Unique ID": "100138", "Name": "Book", "Section": "Paraguay", "Position": "Shelf 1 - Rack 1 - Box 1 - Position 1", "Status": "Available"},
    {"#": "10", "Unique ID": "100139", "Name": "Book", "Section": "Paraguay", "Position": "Shelf 1 - Rack 2 - Box 1 - Position 1", "Status": "Available"},
    {"#": "11", "Unique ID": "100140", "Name": "Book", "Section": "Paraguay", "Position": "Shelf 1 - Rack 2 - Box 1 - Position 2", "Status": "Available"},
    {"#": "12", "Unique ID": "100141", "Name": "Book", "Section": "Paraguay", "Position": "Shelf 1 - Rack 2 - Box 1 - Position 3", "Status": "Lost"},
    {"#": "13", "Unique ID": "100142", "Name": "Book", "Section": "Paraguay", "Position": "Shelf 1 - Rack 2 - Box 1 - Position 4", "Status": "Lost"},
    {"#": "14", "Unique ID": "100143", "Name": "Book", "Section": "Paraguay", "Position": "Shelf 1 - Rack 3 - Box 1 - Position 1", "Status": "Available"},
    {"#": "15", "Unique ID": "100144", "Name": "Book", "Section": "Paraguay", "Position": "Shelf 1 - Rack 3 - Box 1 - Position 2", "Status": "Available"},
    {"#": "16", "Unique ID": "100145", "Name": "Book", "Section": "Paraguay", "Position": "Shelf 1 - Rack 4 - Box 1 - Position 1", "Status": "Checked Out"},
    {"#": "17", "Unique ID": "100146", "Name": "Book", "Section": "Paraguay", "Position": "Shelf 1 - Rack 4 - Box 1 - Position 2", "Status": "Available"},
    {"#": "18", "Unique ID": "100147", "Name": "Book", "Section": "Paraguay", "Position": "Shelf 1 - Rack 4 - Box 1 - Position 3", "Status": "Available"},
    {"#": "19", "Unique ID": "100148", "Name": "Book", "Section": "Paraguay", "Position": "Shelf 1 - Rack 4 - Box 1 - Position 4", "Status": "Checked Out"},
    {"#": "20", "Unique ID": "100149", "Name": "Book", "Section": "Paraguay", "Position": "Shelf 1 - Rack 5 - Box 1 - Position 1", "Status": "Available"}       
];

var self = this;

self.multiSortDict = {};

self.addSort = function(sortName, sortComparatorFunction)
{
    self.multiSortDict[sortName] = sortComparatorFunction;
}

// Example code to add a bunch of sorting methods
self.addSort("Status",(a, b) => a["Status"].localeCompare(b["Status"]));
self.addSort("#", (a, b) => parseFloat(a["#"]) - parseFloat(b["#"]));
self.addSort("Name",(a, b) => a["Name"].localeCompare(b["Name"]));
self.addSort("Unique ID", (a, b) => parseFloat(a["Unique ID"]) - parseFloat(b["Unique ID"]));
self.addSort("Position",(a, b) => a["Position"].localeCompare(b["Position"]));


self.rebuildMultiSort = function (multiSortDict) {
    var sortList = Object.values(multiSortDict);

    var sortMethod = firstBy( sortList[0] ); // Grab the first entry to set the 'firstBy()' method

    for (var i = 1; i < sortList.length; i++) { // Starting at second position
        // I want to dynamically modify this line, being able to append as many 'thenBy()' statements as necessary
        // remove the semicolon from the previous sortMethod assignment
        // append the new 'thenBy()' to assignment
        sortMethod +=
            .thenBy(value);
    }
    return sortMethod;
}
使用上面的示例，理想情况下，我会得到这样的代码行：

var s = firstBy( (a, b) => a["Status"].localeCompare(b["Status"]) )
  .thenBy( (a, b) => parseFloat(a["#"]) - parseFloat(b["#"]) )
  .thenBy( "Name",(a, b) => a["Name"].localeCompare(b["Name"]) )
  .thenBy( (a, b) => parseFloat(a["Unique ID"]) - parseFloat(b["Unique ID"]) )
  .thenBy( "Position",(a, b) => a["Position"].localeCompare(b["Position"]) )
有什么建议吗？

我正在对某些表数据进行多重排序。我想在我的AngularJS网站中动态修改指定排序优先级的代码行。 （我只是在修改...

Answer 1

[几乎在所有情况下，有比采用evil更好的处事方式。