CODEWITHSUNDEEP
.neterror-handlingcode-contracts
Ivo
Ivo

Reputation: 3436

How to handle code contract violations on run-time

I visited devday11 in the Netherlands last week and learned about Code Contract. I am thinking about implementing Code Contract, but the following is still unclear to me. How should I handle runtime code contract violations in my application?

For example I have a layer in my application that calls another layer with a null value. The function called had a Required Contact, so it throws a contract validation error. How should this be handled? So something like this

public string GetOrderSomething(OrderModel order)
{
 Contract.Requires(order != null);
 // jibidi jibeda do something
 }  

//other application layer
private void something()
{
 Class.GetOrderSomething(null);
}

What should be done? Should I handle it with a normal try catch, should I not handle it at all? Is there something "special" I should do?

Upvotes: 2

Views: 190

Answers (3)

Henk Holterman
Henk Holterman

Reputation: 273274

Assuming you already have an 'exception handling' policy in place, you should not have to do anything special.

If would be advisable to pick a specific exception:

public string GetOrderSomething(OrderModel order)
{
  Contract.Requires<ArgumentNullException> (order != null, "order");
  // jibidi jibeda do something
}

Now you can handle the ArgumentNullException in the same manner and place(s) as you would without (before) using contracts.

PS: Hope you liked the talk.

Upvotes: 1

Marino Šimić
Marino Šimić

Reputation: 7342

For this case you should do what you normally would do if there was

if (order == null) { throw new ArgumentNullException(); }

This CodeContract does not mean the class has been destabilized just that you passed a wrong parameter to the method...

However if this would be a Requires for some internal member and you know it should never be null, well that is another story. You would have a permanently unworkable class, and if you are unable to 'fix it' through catching, then probably some fatal exception should be raise and alerted.

Upvotes: 3

k3b
k3b

Reputation: 14755

In my opinion Codecontracts should be used to find programming errors at runtime.

Therefore codecontract-violation-execptions should be handled like avery other programming-error-exception (i.e. IndexOutOfBoundException)

Upvotes: 1

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