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Date: Fri, 23 Apr 2004 17:18:56 -0400
From: Hyman Rosen <hyrosen@mail.com>
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Subject: Re: OOP Language for OS Development
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Date: 2004-04-23T17:18:56-04:00
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Georg Bauhaus wrote:
> So in the general case where the method will have (side)
> effects on object variables I use an if (once) {...} with a
> static bool once, I guess?

What do you mean? A static variable in a function is initialized
the first time control passes through the declarartion, and never
again. So my code is equivalent to your ONCE method - the first
time the function is called, the variable will be initialized, so
you can plant all of the code you want to execute once as part of
that initialization. After that, no matter how many times you call
the function, the initialization code won't be executed.

> Whatever suggests the necessity of ONCE in a language, if it is
 > necessary then being able to write ONCE might have an advantage
 > in my view.

*Shrug* I'm not thrilled with a language feature which allows the
compiler to replace a call to f(2) with an earlier call to f(1),
but maybe that's just me. Ada allows you to decorate a function
with Pragma Pure, and then it can elide multiple calls to a function
if it is called with the same parameters (regardless of whether the
function has side effects).

> So the compiler, compiling seperately, will not know which types
> can be passed to some_C.foo before the linker is run.

In C++, there is no some_C.foo. There is a some_C<T>.foo for each
type T that some_C is instantiated with. Each one is a logically
separate function, and they have nothing to do with each other.