Ch9 Variables and Readability

 

1.Eliminating Intermediate Results

//Here’s an example of a JavaScript function that removes a value from an array:
    var remove_one = function (array, value_to_remove) {
        var index_to_remove = null;
        for (var i = 0; i < array.length; i += 1) {
            if (array[i] === value_to_remove) {
                index_to_remove = i;
                break;
            }
        }
        if (index_to_remove !== null) {
            array.splice(index_to_remove, 1);
        }
    };

 

//sometimes be eliminated by handling the result as soon as you get it:
    var remove_one = function (array, value_to_remove) {
        for (var i = 0; i < array.length; i += 1) {
            if (array[i] === value_to_remove) {
                array.splice(i, 1);
                return;
            }
        }
    };

 

2. if Statement Scope in C++

 

//the person reading this
//code might keep info in mind, wondering if/how it will be used again.
PaymentInfo* info = database.ReadPaymentInfo();
if (info) {
    cout << "User paid: " << info->amount() << endl;
}
// Many more lines of code below ...

//Now the reader can easily forget about info after it goes out of scope.
if (PaymentInfo* info = database.ReadPaymentInfo()) {
    cout << "User paid: " << info->amount() << endl;
}

 

3. Shrink the Scope of Your Variables

 

//two methods, in the following way:
    class LargeClass {

    string str_;

    void Method1() {
        str_ = ...;
        Method2();
    }
    void Method2() {
// Uses str_
    }
// Lots of other methods that don't use str_ ...
};

//For this case, it may make sense to “demote” str_ to be a local variable:
    class LargeClass {
    void Method1() {
        string str = ...;
        Method2(str);
    }

    void Method2(string str) {
// Uses str
    }
// Now other methods can't see str.
};