問題描述
我應該使用方法還是常量標誌？ (Should I use methods or constant flags?)
If I have a database table containing a flag that can have multiple states, should I do this
if ($Object‑>isStateOne()) {
// do something
}
else if ($Object‑>isStateTwo()) {
// do something else
}
else if ($Object‑>isStateThree()) {
// do yet something else
}
or this
switch ($Object‑>getSomeFlag()) {
case ObjectMapper::STATE_ONE:
// do something
break;
case ObjectMapper::STATE_TWO:
// do something else
break;
case ObjectMapper::STATE_THREE:
// do yet something else
break;
}
?
‑‑‑‑‑
參考解法
方法 1:
Whichever makes sense, of course.
The switch looks much cleaner. But, what is this 'state' you are checking? If you're translating a string, use an array, for example.
The if has different behavior from switch. The method calls MAY have side effects. The if is better if multiple states may be active on the object at once, though.
方法 2:
From an OO perspective, both are discouraged. If you have different state, you may want to create a virtual methods, and override it in inherited class. Then based on polymorphism, you can avoid the if, and switch statement.
方法 3:
The second option just seems to be the better solution. IMHO, the unsightly duplication of the comparison code that would accompany the methods of the first solution would be the show‑stopper for me, for example:
public function isStateOne() {
if(strcmp(ObjectMapper::STATE_ONE, '1') == 0) {
return true;
}
}
public function isStateTwo() {
if(strcmp(ObjectMapper::STATE_TWO, '2') == 0) {
return true;
}
}
public function isStateThree() {
if(strcmp(ObjectMapper::STATE_THREE, '3') == 0) {
return true;
}
}
Of course, others might disagree. I just don't like having classes cluttered up with 'almost the same' methods.
(by Chad Johnson、strager、J.W.、karim79)