Class ArsdException

You can catch an ArsdException to get its passed arguments out.

You can pass either a base class or a string as Type.

See the examples for how to use it.

Example

This example shows how you can throw and catch the ad-hoc exception types.

// you can throw and catch by matching the string and argument types
try {
	// throw it with parenthesis after the template args (it uses opCall to construct)
	throw ArsdException!"Test"();
	// you could also `throw new ArsdException!"test";`, but that gets harder with args
	// as we'll see in the following example
	assert(0); // remove from docs
} catch(ArsdException!"Test" e) { // catch it without them
	// this has no useful information except for the type
	// but you can catch it like this and it is still more than generic Exception
}

// an exception's job is to deliver useful information up the chain
// and you can do that easily by passing arguments:

try {
	throw ArsdException!"Test"(4, "four");
	// you could also `throw new ArsdException!("Test", int, string)(4, "four")`
	// but now you start to see how the opCall convenience constructor simplifies things
	assert(0); // remove from docs
} catch(ArsdException!("Test", int, string) e) { // catch it and use info by specifying types
	assert(e.data[0] == 4); // and extract arguments like this
	assert(e.data[1] == "four");
}

// a throw site can add additional information without breaking code that catches just some
// generally speaking, each additional argument creates a new subclass on top of the previous args
// so you can cast

try {
	throw ArsdException!"Test"(4, "four", 9);
	assert(0); // remove from docs
} catch(ArsdException!("Test", int, string) e) { // this catch still works
	assert(e.data[0] == 4);
	assert(e.data[1] == "four");
	// but if you were to print it, all the members would be there
	// import std.stdio; writeln(e); // would show something like:
	/+
		ArsdException!("Test", int, string, int)@file.d(line):
		[0] int: 4
		[1] string: four
		[2] int: 9
	+/
	// indicating that there's additional information available if you wanted to process it

	// and meanwhile:
	ArsdException!("Test", int) e2 = e; // this implicit cast works thanks to the parent-child relationship
	ArsdException!"Test" e3 = e; // this works too, the base type/string still matches

	// so catching those types would work too
}