《重構：改善既有代碼的設計》——關於代碼註釋的嘮叨

　　這幾天在看《重構：改善既有代碼的設計》英文評註版這本書，之前簡單看過這本書，但並非看的特別深刻。通過了一段時間的「磨練」，如今回來從新看這本書，又不少想法。

　　首先，這本書是一本好書，我感受是軟件工程師必看的一本書，並且若是有大量的編碼經驗看這本書會收穫很大。這本書主要內容是代碼重構。

　　在書中第3章中有這樣一段話是用來描述代碼註釋的：

　　A good time to use a comment is when you don't know what to do. In addition to describe what is going on,comments can indicate areas in which you aren't  sure. A comments is a good place to say why you did something. 

　　書中的中文評註以下：

　　高明的程序員絕對不會將註釋做爲說明代碼的重要手段。註釋就像咖啡，適量飲用能夠提精神，一旦過量，就變得過分亢奮了。

　　我我的感受上面兩端話言簡意賅的說出了註釋的做用，註釋只是代碼的一個輔助，是爲了咱們更好的理解代碼。其實關於代碼風格和註釋風格，每一個人都有本身的見解。我以爲都沒有錯，只不過每一個人的見解不同。就像我，我我的認爲代碼首先是給程序員看的，其次是給機器看的。由於，發明高級程序語言的目的之一就是爲了讓人們更好的閱讀代碼。變量和方法的命名就能夠說明變量的做用，若是說不清楚，可使用註釋。但若是是簡單易懂的變量，我以爲寫註釋不必。

1 string personName;    // 人員姓名

　　就像上面的一行代碼，我認爲不必寫這個註釋，不要由於寫註釋而去寫註釋。此外，在最近閱讀Java源代碼的時候，我發現Java源代碼註釋有不少特色。

 1     /**
 2      * Compares two strings lexicographically.
 3      * The comparison is based on the Unicode value of each character in
 4      * the strings. The character sequence represented by this
 5      * {@code String} object is compared lexicographically to the
 6      * character sequence represented by the argument string. The result is
 7      * a negative integer if this {@code String} object
 8      * lexicographically precedes the argument string. The result is a
 9      * positive integer if this {@code String} object lexicographically
10      * follows the argument string. The result is zero if the strings
11      * are equal; {@code compareTo} returns {@code 0} exactly when
12      * the {@link #equals(Object)} method would return {@code true}.
13      * <p>
14      * This is the definition of lexicographic ordering. If two strings are
15      * different, then either they have different characters at some index
16      * that is a valid index for both strings, or their lengths are different,
17      * or both. If they have different characters at one or more index
18      * positions, let <i>k</i> be the smallest such index; then the string
19      * whose character at position <i>k</i> has the smaller value, as
20      * determined by using the &lt; operator, lexicographically precedes the
21      * other string. In this case, {@code compareTo} returns the
22      * difference of the two character values at position {@code k} in
23      * the two string -- that is, the value:
24      * <blockquote><pre>
25      * this.charAt(k)-anotherString.charAt(k)
26      * </pre></blockquote>
27      * If there is no index position at which they differ, then the shorter
28      * string lexicographically precedes the longer string. In this case,
29      * {@code compareTo} returns the difference of the lengths of the
30      * strings -- that is, the value:
31      * <blockquote><pre>
32      * this.length()-anotherString.length()
33      * </pre></blockquote>
34      *
35      * @param   anotherString   the {@code String} to be compared.
36      * @return  the value {@code 0} if the argument string is equal to
37      *          this string; a value less than {@code 0} if this string
38      *          is lexicographically less than the string argument; and a
39      *          value greater than {@code 0} if this string is
40      *          lexicographically greater than the string argument.
41      */
42     public int compareTo(String anotherString) {
43         int len1 = value.length;
44         int len2 = anotherString.value.length;
45         int lim = Math.min(len1, len2);
46         char v1[] = value;
47         char v2[] = anotherString.value;
48 
49         int k = 0;
50         while (k < lim) {
51             char c1 = v1[k];
52             char c2 = v2[k];
53             if (c1 != c2) {
54                 return c1 - c2;
55             }
56             k++;
57         }
58         return len1 - len2;
59     }

　　這是String類型的compareTo()函數的源代碼，註釋比較多，但註釋比較集中，並無影響了代碼的閱讀。我以爲把一些說明性的註釋寫在文件、類和函數的開頭，這樣不只有助於閱讀代碼，也不會喧賓奪主。其次Java源代碼的變量命名很是優美，值得我去學習。

　　這就是我對註釋的一些嘮叨。