Date: Wed, 24 Nov 2004 15:29:25 -0500 From: Charles Swiger <cswiger@mac.com> To: John-Mark Gurney <gurney_j@resnet.uoregon.edu> Cc: freebsd-current@freebsd.org Subject: Re: Transparent bridges (a. k. a. HUB-to-PCI bridges)? Message-ID: <88534D8A-3E57-11D9-BD47-003065ABFD92@mac.com> In-Reply-To: <20041124184124.GA5166@funkthat.com> References: <200411231226.38172.jkim@niksun.com> <200411231343.22760.jhb@FreeBSD.org> <20041124002603.GD20881@squash.dsto.defence.gov.au> <41A416E7.4030107@mac.com> <20041124184124.GA5166@funkthat.com>
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On Nov 24, 2004, at 1:41 PM, John-Mark Gurney wrote: >> True OOP involves encapsulation, polymorphism, and inheritence, and >> requires language support which is not really available in pure C. >> That >> being said, careful programming in C lets you create several >> closely-related structs for different types of "objects" which can >> all be >> utilized by a common set of functions. > > You should read up on KOBJ's which is how device_t's are implemented > in FreeBSD... kobj's are a loop more OOP that you think... OK. I've taken a look at sys/kobj.h and sys/kern/subr_kobj.c, is there something else I should read? My take on it, for what it is worth, is that KOBJs implement the class versus instance paradigm, have a dynamic runtime & method dispatch rather similar to the implementation of Objective-C or virtual C++ methods. Yes, this is a lot more object-oriented than what I said about being disciplined using C struct's. :-) Things that one still doesn't have is encapsulation in the sense of data hiding; what Java calls protected or private ivar's. Object memory management for instances via reference counting or GC would also be nice, although I even saw a hint of that in kobj_delete(), as well as a bit of the alloc/init & delete/free seperation. -- -Chuck
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