一、Remove Control Flag（移除控制标记）
动机（Motivation）
以break语句或return语句取代控制标记。
示例
01 |
public void CheckSecurity(string[] people) |
02 |
{ |
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string found = string.Empty; |
04 |
for (int i = 0; i < people.Length; i++) |
05 |
{ |
06 |
if (found.Equals("")) |
07 |
{ |
08 |
if (people[i].Equals("Don")) |
09 |
{ |
10 |
found = "Don"; |
11 |
} |
12 |
if (people[i].Equals("John")) |
13 |
{ |
14 |
found = "John"; |
15 |
} |
16 |
} |
17 |
} |
18 |
SomeDataCode(found); |
19 |
} |
改为
01 |
public void CheckSecurity(string[] people) |
02 |
{ |
03 |
string found = string.Empty; |
04 |
for (int i = 0; i < people.Length; i++) |
05 |
{ |
06 |
if (found.Equals("")) |
07 |
{ |
08 |
if (people[i].Equals("Don")) |
09 |
{ |
10 |
found = "Don"; |
11 |
break; |
12 |
} |
13 |
if (people[i].Equals("John")) |
14 |
{ |
15 |
found = "John"; |
16 |
break; |
17 |
} |
18 |
} |
19 |
} |
20 |
SomeDataCode(found); |
21 |
} |
示例
01 |
public string FindPeople(string[] people) |
02 |
{ |
03 |
string found = string.Empty; |
04 |
for (int i = 0; i < people.Length; i++) |
05 |
{ |
06 |
if (found.Equals("")) |
07 |
{ |
08 |
if (people[i].Equals("Don")) |
09 |
{ |
10 |
found = "Don"; |
11 |
} |
12 |
if (people[i].Equals("John")) |
13 |
{ |
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found = "John"; |
15 |
} |
16 |
} |
17 |
} |
18 |
return found; |
19 |
} |
改为
01 |
public string FindPeople(string[] people) |
02 |
{ |
03 |
string found = string.Empty; |
04 |
for (int i = 0; i < people.Length; i++) |
05 |
{ |
06 |
if (found.Equals("")) |
07 |
{ |
08 |
if (people[i].Equals("Don")) |
09 |
{ |
10 |
return "Don"; |
11 |
} |
12 |
if (people[i].Equals("John")) |
13 |
{ |
14 |
return "John"; |
15 |
} |
16 |
} |
17 |
} |
18 |
return string.Empty; |
19 |
} |
二、Replace Nested Conditional with Guard Clauses（以卫语句取代嵌套条件式）
动机（Motivation）
使用卫语句（guard clauses）表现所有特殊情况。
示例
01 |
public double GetPayAmount() |
02 |
{ |
03 |
double result; |
04 |
if (IsDead) |
05 |
result = DeadAmount(); |
06 |
else |
07 |
{ |
08 |
if (IsSeparated) |
09 |
result = SeparatedAmount(); |
10 |
else |
11 |
{ |
12 |
if (IsRetired) |
13 |
result = RetiredPayAmount(); |
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else |
15 |
result = NormalPayAmount(); |
16 |
} |
17 |
} |
18 |
return result; |
19 |
} |
改为
01 |
public double GetPayAmount() |
02 |
{ |
03 |
if (IsDead) |
04 |
return DeadAmount(); |
05 |
if (IsSeparated) |
06 |
return SeparatedAmount(); |
07 |
if (IsRetired) |
08 |
return RetiredPayAmount(); |
09 |
return NormalPayAmount(); |
10 |
} |
三、Introduce Null Object （引入Null对象）
动机（Motivation）
将null value（无效值）替换为null object（无效物）
示例
1 |
if (customer == null) |
2 |
plan = BillingPlan.Basic(); |
3 |
else |
4 |
plan = customer.GetPlan(); |
改为
1 |
public double GetPayAmount() |
2 |
{ |
3 |
if (customer.IsNull()) |
4 |
plan = BillingPlan.Basic(); |
5 |
else |
6 |
plan = customer.GetPlan(); |
7 |
} |
四、Rename Method（重新命名函数）
动机（Motivation）
修改函数名称让它人容易理解它的作用
示例
1 |
public int Getinvcdtlmt() |
2 |
{ |
3 |
return 10; |
4 |
} |
改为
1 |
public int GetInvoiceAbleCreditLimit() |
2 |
{ |
3 |
return 10; |
4 |
} |
五、Separate Query from Modifier（将查询函数和修改函数分离）
动机（Motivation）
建立两个不同的函数，其中一个负责查询，另一个负责修改。
示例
01 |
public string FindPeople(string[] people) |
02 |
{ |
03 |
string found = string.Empty; |
04 |
for (int i = 0; i < people.Length; i++) |
05 |
{ |
06 |
if (found.Equals("")) |
07 |
{ |
08 |
if (people[i].Equals("Don")) |
09 |
{ |
10 |
SendMail(); |
11 |
return "Don"; |
12 |
} |
13 |
if (people[i].Equals("John")) |
14 |
{ |
15 |
SendMail(); |
16 |
return "John"; |
17 |
} |
18 |
} |
19 |
} |
20 |
return string.Empty; |
21 |
} |
改为
01 |
public string FindPeople(string[] people) |
02 |
{ |
03 |
string found = FindPeopleOne(people); |
04 |
SendMailToPeople(found); |
05 |
} |
06 |
07 |
public string FindPeopleOne(string[] people) |
08 |
{ |
09 |
string found = string.Empty; |
10 |
for (int i = 0; i < people.Length; i++) |
11 |
{ |
12 |
if (found.Equals("")) |
13 |
{ |
14 |
if (people[i].Equals("Don")) |
15 |
{ |
16 |
return "Don"; |
17 |
} |
18 |
if (people[i].Equals("John")) |
19 |
{ |
20 |
return "John"; |
21 |
} |
22 |
} |
23 |
} |
24 |
return string.Empty; |
25 |
} |
26 |
27 |
public void SendMailToPeople(string people) |
28 |
{ |
29 |
if (!string.IsNullOrEmpty(people)) |
30 |
SendMail(); |
31 |
} |
六、Parameterize Method（令函数携带参数）
动机（Motivation）
建立单一函数，以参数表达那些不同的值
示例
1 |
public double TenPercentRaise() |
2 |
{ |
3 |
return salary * 1.1; |
4 |
} |
5 |
6 |
public double FivePercentRaise() |
7 |
{ |
8 |
return salary * 1.05; |
9 |
} |
改为
1 |
public double Raise(double factor) |
2 |
{ |
3 |
return salary * factor; |
4 |
} |
七、Replace Parameter with Explicit Methods（以明确函数取代参数）
动机（Motivation）
针对该参数的每一个可能值，建立一个独立函数。
示例
01 |
private int _height; |
02 |
private int _width; |
03 |
04 |
public void SetValue(string name, int value) |
05 |
{ |
06 |
if (name.Equals("height")) |
07 |
{ |
08 |
_height = value; |
09 |
return; |
10 |
} |
11 |
if (name.Equals("width")) |
12 |
{ |
13 |
_width = value; |
14 |
return; |
15 |
} |
16 |
} |
改为
01 |
private int _height; |
02 |
private int _width; |
03 |
04 |
public int Height |
05 |
{ |
06 |
set { _height = value; } |
07 |
} |
08 |
09 |
public int Width |
10 |
{ |
11 |
set { _width = value; } |
12 |
} |