Path: utzoo!utgpu!news-server.csri.toronto.edu!torsqnt!geac!alias!fred!rae
From: rae@gpu.utcs.toronto.edu (Reid Ellis)
Newsgroups: comp.lang.c++
Subject: constructor parameters
Summary: How do you specify local variables for parameters to initilizer calls?
Keywords: constructor, parameters, has-a
Message-ID: <rae.654809627@fred>
Date: 1 Oct 90 19:33:47 GMT
Sender: Reid Ellis <rae%alias@csri.toronto.edu>
Reply-To: Reid Ellis <rae@gpu.utcs.toronto.edu>
Organization: Alias Research, Inc. Toronto ON Canada
Lines: 46

When you are writing a constructor for a class, it is useful to
initialize any class objects your class continas like this:

	X::X()
	: location(12, 34), value(1.23), direction(X::dir())
	{
		// ...
	}

Note that the arguments to constructor initializers can be fairly
complex expressions, not just constants.

My problem relates to constructors that return a value via a
reference parameter.  How does one access these results?  e.g.,
let's say I have these classes:

	struct a { a(int &); };
	struct b { b(int &); };
	struct c { c(int &); };

Now I have this class:

	struct X {
		a cat;
		b dog;
		c mouse;
	};

What I *want* to write is something like this:

	X::X()
	: cat(int aResult), dog(int bResult), mouse(int cResult)
	{
		switch(aResult) // ...
		...
	}

But this is illegal.  Other options include having an int in the
class for each object, or haing a static int in the source file
for each object, but these seem less than elegant.

Suggestions?
					Reid
--
Reid Ellis  264 Broadway Avenue, Toronto ON, M4P 1V9               Canada
rae@gpu.utcs.toronto.edu || rae%alias@csri.toronto.edu || +1 416 487 1383