asguard

Simple code contracts for ActionScript.

Contracts

Contracts provides ways to require pre-conditions are met and to ensure that post-conditions are satisfied.

public function foo(bar:String):String
{
	// pre-condition checking
	Contracts.require.isNotNull(bar);
	
	var upperBar:String = bar.toUpperCase();
	
	// post-condition checking
	Contracts.ensure.isNotNull(upperBar);
	Contracts.ensure.isEqual(bar.length, upperBar.length);
	
	return upperBar;
}

Conditions

It is often better to define pre- and post-conditions together in your code. To facilitate this scenario you can define a set of conditions with which to validate against later. The validate method of the Conditions class returns the value being validated so that it can be immediately returned.

public function foo(bar:String):String
{
	// pre-condition checking
	Contracts.require.isNotNull(bar);
	// post-condition checking
	var postConditions:Conditions = Contract.ensure.createConditions();
	postConditions.isNotNull();
	postConditions.isTrue(function(result:String):Boolean {
		return bar.length == result.length;
	});
	
	var upperBar:String = bar.toUpperCase();
	
	return postConditions.validate(upperBar);
}

Also, the other methods on the Conditions class are self-returning so that checks can be chained together.

public function foo(bar:String):String
{
	// pre-condition checking
	Contracts.require.isNotNull(bar);
	// post-condition checking
	var postConditions:Conditions = Contract.ensure.createConditions()
									.isNotNull()
									.isTrue(function(result:String):Boolean {
										return bar.length == result.length;
									});
	
	var upperBar:String = bar.toUpperCase();
	
	return postConditions.validate(upperBar);
}

Contract Violations

Behavior is different depending on Debug and Release builds. When built in Debug mode, contract voilations will throw a ContractViolatedError. When built in Release mode, a ContractViolatedEvent will be dispatched on Contracts.eventDispatcher.

License

This content is released under the MIT License (See LICENSE).

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