Re: Where to include header files - relates to last question on variable scope

FROM : Ole Voß
DATE : Sun Oct 31 23:25:45 2004

Chris Hanson wrote:

> On Oct 31, 2004, at 7:10 AM, Ole Voss wrote:
>

>> This also means, that I have to include the header file wherever I
>> need it?
>> That could mean that the same class has to be recompiled tens of times -
>> right?

>
>
> You need to distinguish between the declaration and the definition.
>
> The definition needs to be compiled only once.  The declaration needs
> to appear prior to its use in any compilation unit that needs to make
> use of the information in it; that's what #include and #import do.
>
> This is true for all of C, C++, and Objective-C and is fundamental to
> these languages' compilation model.
>

>> So what possibilities do I have to create global variables?

>
>
> You create global variables in Objective-C in exactly same way that
> you create them in C.  Declare your global variable in a header file
> as extern, and define it in a single implementation file.
>
>  -- Chris
>


Yes, that does sound feasible but I would still have to re-include this
header file in every class that I use it in?

I'm just spoilt because I've been programming Perl for over five years
now and that language just does everything for you ;-)

If I include my module once - it just stays available to all my other
modules and I don't have to re-include it.

C is too far away to even remember...



Thank you,


Ole.