Replace Parameter with Method
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(New page: == Motivation == ''Refactoring'' Martin Fowler 1999 states that: "If a method can get a value that is passed in as a parameter by another means, it should." == Example == An object ...) |
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''Refactoring'' [[Martin Fowler 1999]] states that: "If a method can get a value that is passed in as a parameter by another means, it should." | ''Refactoring'' [[Martin Fowler 1999]] states that: "If a method can get a value that is passed in as a parameter by another means, it should." | ||
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| + | In some cases, this could lead to a violation of [[Tell, don't ask]]. This would occur where these method calls are occurring between different classes rather than within one class. | ||
== Example == | == Example == | ||
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return discountedPrice; | return discountedPrice; | ||
} | } | ||
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| + | == See Also == | ||
| + | * [[Tell, don't ask]] | ||
Latest revision as of 21:34, 14 October 2009
Motivation
Refactoring Martin Fowler 1999 states that: "If a method can get a value that is passed in as a parameter by another means, it should."
In some cases, this could lead to a violation of Tell, don't ask. This would occur where these method calls are occurring between different classes rather than within one class.
Example
An object invokes a method, then passes the result as a parameter for a method. The receiver can also invoke this method. So the best idea is to remove the parameter and let the receiver invoke the method.
int basePrice = quantity * itemPrice; discountLevel = getDiscountLevel(); double finalPrice = discountedPrice(basePrice, discountLevel);
Above we have some code, but lets remove the discountLevel parameter from discountedPrice(basePrice, discountLevel). Now we have:
int basePrice = quantity * itemPrice; double finalPrice = discountedPrice(basePrice);
The discountedPrice(basePrice) method now looks like:
discountedPrice(basePrice)
{
int discountLevel = getDiscountLevel();
//does calculation type stuff here
return discountedPrice;
}
