如何消除空参数而不使用冗余代码

发布于 2024-12-12 05:24:36 字数 392 浏览 0 评论 0原文

例如：

getBooks(author, title)

如果允许作者为空，将返回具有特定标题的所有书籍
如果允许标题为空，将返回特定作者的所有书籍
如果允许两者都为空，则将返回所有书籍，无论标题或作者

如何消除this，具有以下功能：

getBooks(author) 
getBooks(title)  
getBooks(author, title)  
getBooks()

在新函数中，可能存在冗余代码，或者如果我们将这些冗余代码分组到一个函数中，我们仍然会进入一个具有空参数的函数。有什么更好的方法来处理这个问题——没有冗余代码，也没有空参数？

原文

For example:

getBooks(author, title)

If allowing author to be null, would return all books with specific title
If allowing title to be null, would return all books for the specific author
If allowing both to be null, would return all books regardless of title or author

To eliminate this, have the following functions:

getBooks(author) 
getBooks(title)  
getBooks(author, title)  
getBooks()

In the new functions, there might be redundant codes or if we group those redundant codes into a function, we will still get into a function having null parameters. What's a better way to handle this - no redundant code and no null parameters?

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活雷疯 2024-12-19 05:24:36

不要过载太多：

getBooksByAuthor(author) 
getBooksByTitle(title)  
getBooksByAuthorAndTitle(author, title)  
getBooks()

请注意，这不会减少代码重用：这些方法可以重用/共享它们在实现中需要的任何代码

Don't overload so much:

getBooksByAuthor(author) 
getBooksByTitle(title)  
getBooksByAuthorAndTitle(author, title)  
getBooks()

Note that this will not reduce code reuse: These methods could reuse/share whatever code they needed to in their implementations

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风筝在阴天搁浅。 2024-12-19 05:24:36

您可以使用常量来表示要执行的搜索类型，并检查是否传递了参数（未经测试且已检查错误）：

public static final int R_AUTH = 1;
public static final int R_BOOK = 2;
public static final int R_ALL = 3;

public bookSearch( int searchType, String... search )
{
    switch( searchType )
    {
        case R_AUTH:
          // search based off of (String)search[0].stringValue();
        break;
        case R_ALL:
          // load all
        break;
    }
}

bookSearch(R_ALL);
bookSearch(R_AUTH, "Poe");

You could use a constant to denote what type of search to do, and check to see if a param was passed (very untested and error checked):

public static final int R_AUTH = 1;
public static final int R_BOOK = 2;
public static final int R_ALL = 3;

public bookSearch( int searchType, String... search )
{
    switch( searchType )
    {
        case R_AUTH:
          // search based off of (String)search[0].stringValue();
        break;
        case R_ALL:
          // load all
        break;
    }
}

bookSearch(R_ALL);
bookSearch(R_AUTH, "Poe");

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陪我终i 2024-12-19 05:24:36

假设作者和标题是字符串，您可以执行以下操作：

public List getBooks(String params ...) {
    if (params.length == 0) { //search 
     //do search all books regardless of title or author
    } else if (params.length == 2 && "cte_author".equals(params[1])) {
     //do search  by author
    } else if (params.length == 2 && "cte_title".equals(params[1])) {
     //do search by title
    } else if (params.length == 2){
     //do search by title and book
    } else {
     //throw exception
    }
}

因此您可以按如下方式使用此方法：

getBooks();
getBooks("Gabriel Garcia Marquez", "cte_author");
getBooks("Cien anios de soledad", "cte_title");
getBooks("Gabriel Garcia Marquez","Cien anios de soledad");

Assuming that author and title are Strings you can do the following:

public List getBooks(String params ...) {
    if (params.length == 0) { //search 
     //do search all books regardless of title or author
    } else if (params.length == 2 && "cte_author".equals(params[1])) {
     //do search  by author
    } else if (params.length == 2 && "cte_title".equals(params[1])) {
     //do search by title
    } else if (params.length == 2){
     //do search by title and book
    } else {
     //throw exception
    }
}

So you can use this method as following:

getBooks();
getBooks("Gabriel Garcia Marquez", "cte_author");
getBooks("Cien anios de soledad", "cte_title");
getBooks("Gabriel Garcia Marquez","Cien anios de soledad");

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π浅易 2024-12-19 05:24:36

尝试这种方法：

getAllBooks()            {return getBooks("", "");}
getBooksByAuthor(author) {return getBooks(author, "");}
getBooksByTitle(title)   {return getBooks("", title);}
getBooksByAuthorAndTitle(author, title)
{
    if(author.equals("") && title.equals(""))
    {
        return //your book list
    }
    else if(author.equals(""))
    {
        return //a list of books with the given title
    }
    else if(title.equals(""))
    {
        return //a list of books with given author
    }
    else
    {
        return //a list of books with the given title and author
    }
}

编辑：
更新以避免歧义。

Try this approach:

getAllBooks()            {return getBooks("", "");}
getBooksByAuthor(author) {return getBooks(author, "");}
getBooksByTitle(title)   {return getBooks("", title);}
getBooksByAuthorAndTitle(author, title)
{
    if(author.equals("") && title.equals(""))
    {
        return //your book list
    }
    else if(author.equals(""))
    {
        return //a list of books with the given title
    }
    else if(title.equals(""))
    {
        return //a list of books with given author
    }
    else
    {
        return //a list of books with the given title and author
    }
}

Edit:
Updated to circumvent ambiguity.

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