Basic¶
條件位運算BitwiseOperatorInConditional¶
Since: 0.6
位運算是不利於後期維護和理解的，雖然有時候這樣計算速度比較快
定義類: oclint-rules/rules/basic/BitwiseOperatorInConditionalRule.cpp
Example:
void example(int a, int b)
{
if (a | b)
{
}
if (a & b)
{
}
}
錯誤Null檢查BrokenNullCheck¶
Since: 0.7
錯誤的空檢查會讓程序崩潰
定義類: oclint-rules/rules/basic/BrokenNullCheckRule.cpp
Example:
void m(A *a, B *b)
{
if (a != NULL || a->bar(b))
{
}
if (a == NULL && a->bar(b))
{
}
}
錯誤Nil檢查BrokenNilCheck¶
Since: 0.7
在某些情況下，在Objective-C中破零檢查返回結果剛好相反。
定義類: oclint-rules/rules/basic/BrokenNullCheckRule.cpp
Example:
+ (void)compare:(A *)obj1 withOther:(A *)obj2
{
if (obj1 || [obj1 isEqualTo:obj2])
{
}
if (!obj1 && ![obj1 isEqualTo:obj2])
{
}
}
BrokenOddnessCheck¶
Since: 0.6
檢查 x % 2 == 1 如果是負數，就會出現異常.
應該使用 x & 1 == 1,
or x % 2 != 0 替換.
定義類: oclint-rules/rules/basic/BrokenOddnessCheckRule.cpp
Example:
void example()
{
if (x % 2 == 1) // violation
{
}
if (foo() % 2 == 1) // violation
{
}
}
可以合併的IF語句 CollapsibleIfStatements¶
Since: 0.6
可以合併的連續兩個if,應該合併，提高代碼的可讀性.
定義類: oclint-rules/rules/basic/CollapsibleIfStatementsRule.cpp
Example:
void example(bool x, bool y)
{
if (x) // these two if statements can be
{
if (y) // combined to if (x && y)
{
foo();
}
}
}
恆定條件運算 ConstantConditionalOperator¶
Since: 0.6
條件運算符 結果已經確定的條件運算.
定義類: oclint-rules/rules/basic/ConstantConditionalOperatorRule.cpp
Example:
void example()
{
int a = 1 == 1 ? 1 : 0; // 1 == 1 is actually always true
}
IF表達式爲確定ConstantIfExpression¶
Since: 0.2
if 表達式的條件是已經確定的true 或者else
定義類: oclint-rules/rules/basic/ConstantIfExpressionRule.cpp
Example:
void example()
{
if (true) // always true
{
foo();
}
if (1 == 0) // always false
{
bar();
}
}
無效代碼DeadCode¶
Since: 0.4
在 return, break, continue,
and throw 之後的代碼都是無效的
定義類: oclint-rules/rules/basic/DeadCodeRule.cpp
Example:
void example(id collection)
{
for (id it in collection)
{
continue;
int i1; // dead code
}
return;
int i2; // dead code
}
雙重否定 DoubleNegative¶
Since: 0.6
使用雙重否定沒有意義
定義類: oclint-rules/rules/basic/DoubleNegativeRule.cpp
Example:
void example()
{
int b1 = !!1;
int b2 = ~~1;
}
For應該轉換爲While ForLoopShouldBeWhileLoop¶
Since: 0.6
一些情況下For循環應該轉換爲While，使代碼更簡潔
定義類: oclint-rules/rules/basic/ForLoopShouldBeWhileLoopRule.cpp
Example:
void example(int a)
{
for (; a < 100;)
{
foo(a);
}
}
Goto語句 GotoStatement¶
Since: 0.6
定義類: oclint-rules/rules/basic/GotoStatementRule.cpp
Example:
void example()
{
A:
a();
goto A; // Considered Harmful
}
References:
Edsger Dijkstra (March 1968). “Go To Statement Considered Harmful”. Communications of the ACM (PDF) 11 (3): 147–148. doi:10.1145/362929.362947.
混亂的增量 JumbledIncrementer¶
Since: 0.7
混亂的增量計算，使代碼很難閱讀
定義類: oclint-rules/rules/basic/JumbledIncrementerRule.cpp
Example:
void aMethod(int a) {
for (int i = 0; i < a; i++) {
for (int j = 0; j < a; i++) { // references both 'i' and 'j'
}
}
}
錯位的Null檢查 MisplacedNullCheck¶
Since: 0.7
（空檢查應該在其他運算之前）The null check is misplaced. In C and C++, sending a message to a null pointer could crash the app. When null is misplaced, either the check is useless or it’s incorrect.
This rule is defined by the following class: oclint-rules/rules/basic/MisplacedNullCheckRule.cpp
Example:
void m(A *a, B *b)
{
if (a->bar(b) && a != NULL) // violation
{
}
if (a->bar(b) || !a) // violation
{
}
}
錯位的Nil檢查 MisplacedNilCheck¶
Since: 0.7
（nil檢查應該在其他運算之前）The nil check is misplaced. In Objective-C, sending a message to a nil pointer simply does nothing. But code readers may be confused about the misplaced nil check.
This rule is defined by the following class: oclint-rules/rules/basic/MisplacedNilCheckRule.cpp
Example:
+ (void)compare:(A *)obj1 withOther:(A *)obj2
{
if ([obj1 isEqualTo:obj2] && obj1)
{
}
if (![obj1 isEqualTo:obj2] || obj1 == nil)
{
}
}
多餘運算符 MultipleUnaryOperator¶
Since: 0.6
多餘的運算符應該簡化，便於閱讀
This rule is defined by the following class: oclint-rules/rules/basic/MultipleUnaryOperatorRule.cpp
Example:
void example()
{
int b = -(+(!(~1)));
}
從Finally 返回 ReturnFromFinallyBlock¶
Since: 0.6
不建議從Finally 返回
定義類: oclint-rules/rules/basic/ReturnFromFinallyBlockRule.cpp
Example:
void example()
{
@try
{
foo();
}
@catch(id ex)
{
bar();
}
@finally
{
return; // this can discard exceptions.
}
}
Finally拋出異常 ThrowExceptionFromFinallyBlock¶
Since: 0.6
從Finally塊拋出異常，可能掩蓋其他的錯誤
定義類: oclint-rules/rules/basic/ThrowExceptionFromFinallyBlockRule.cpp
Example:
void example()
{
@try {;}
@catch(id ex) {;}
@finally {
id ex1;
@throw ex1; // this throws an exception
NSException *ex2 = [NSException new];
[ex2 raise]; // this throws an exception, too
}
}