Replace Parameter with Method

//esto sale de sourcemaking.com replace parameter with method <-making methods calls simpler

el proceso entero con comentarios se puede seguir mediante el archivo de MoonEdit (programa muy chulo , gratis y sin peso apenas) replace parameter with method

CODIGO INICIAL

public double getPrice()

{

int basePrice = _quantity * _itemPrice;

int discountLevel;

if (_quantity > 300) discountLevel = 3;

else if (_quantity > 200) discountLevel = 2;

else discountLevel = 1;

double finalPrice = discountedPrice (basePrice, discountLevel);

return finalPrice;

}




private double discountedPrice (int basePrice, int discountLevel)

{

if (discountLevel == 2) return basePrice * 0.1;

elseif (discountLevel == 3) return basePrice * 0.2;

else return basePrice * 0.05;

}

CODIGO FINAL

public double getPrice()

{

if (Discount.isEnoughQuantityForPlatinum(_quantity))

return getBasePrice() * Discount.PLATINUM.getPercentage();

elseif (Discount.isEnoughQuantityForPlus(_quantity))

return getBasePrice() * Discount.PLUS.getPercentage();

else

return getBasePrice() * Discount.NORMAL.getPercentage();

}

private int getBasePrice()

{

return _quantity * _itemPrice;

}

class Discount

{

static final int MIN_QUANTITY_FOR_PLATINUM = 300;

static final int MIN_QUANTITY_FOR_PLUS = 200;




static final int PLATUNUM_LEVEL = 3;

static final int PLUS_LEVEL = 2;

static final int NORMAL_LEVEL = 1;

static final float PLATINUM__PERCENTAGE = 0.2;

static final float PLUS__PERCENTAGE = 0.1;

static final float NORMAL_PERCENTAGE = 0,05;

public static final Discount NORMAL = new Discount (NORMAL_LEVEL , NORMAL_PERCENTAGE);

public static final Discount PLUS = new Discount (PLUS_LEVEL , PLUS_PERCENTAGE);

public static final Discount PLATINUM = new Discount (PLATINUM_LEVEL , PLATINUM_PERCENTAGE);

private final int _level;

private final float _percentage;




private Discount(int level,float percentage)

{

_level = level;

_percentage = percentage;

}

public getLevel()

{

return _level;

}

public getPercentage()

{

return _percentage;

}

public boolean isEnoughQuantityForPlus(quantity)

{

if (quantity > MIN_QUANTITY_FOR_PLUS) return true;

return false;

}

public boolean isEnoughQuantityForPlatinum(quantity)

{

if (quantity > MIN_QUANTITY_FOR_PLATINUM) return true;

return false;

}

bad Smell: getPrice() -- long method , finalPrice variable is always the discount Calculated Price

refactoring used :

replace parameter with method <- making methods calls simpler

invented name refactor (i don´t know if its a current name for this)

introduce multible return points <- simplifying Conditional Expressions

inline method <- componsing methods

replace Magic Number with Symbolic constant <- organizing data

replace type code with class <- organizing data

move method <- move features between objects

consolidate conditional expression <- simplifying conditional expressions