C++ needs the most elaborate mechanism because of its legacy preprocessor: http://en.wikipedia.org/wiki/Include_guard
other languages like Java just refrain from having the compiler barf if it's done twice, mostly. I don't know of any other languages that need an elaborate mechanism, but I'm sure there are some; anyone here come across one? On Thu, Sep 12, 2013 at 3:17 AM, Piaget Modeler <[email protected]>wrote: > Any pointers to those mechanisms? > > Cheers, > > ~PM > > ------------------------------ > Date: Thu, 12 Sep 2013 03:12:13 +0100 > Subject: Re: [agi] Module re-definitions > From: [email protected] > To: [email protected] > > > If ( exists(table(A))) then drop table A ; > > Create table A as blah blah blah... > > > ee? no! that would break everything that refers to table A. modify it in > place instead. > > **** > > ** ** > > In 3 GL languages like C++, Java, etc. when a code module is accidentally > > included twice in a source file, what exactly happens? Does the compiler** > ** > > redefine or ignore the functions or objects in the duplicate module? What > **** > > about interpreted languages like python? > > > what you want is usually that importing a module is idempotent, i.e. doing > it twice is the same as doing it once. The mechanisms by which this is > achieved are very different in C++ versus Java but it is achieved > nonetheless. > *AGI* | Archives <https://www.listbox.com/member/archive/303/=now> > <https://www.listbox.com/member/archive/rss/303/19999924-4a978ccc> | > Modify <https://www.listbox.com/member/?&;> Your Subscription > <http://www.listbox.com> > *AGI* | Archives <https://www.listbox.com/member/archive/303/=now> > <https://www.listbox.com/member/archive/rss/303/1658954-f53d1a3f> | > Modify<https://www.listbox.com/member/?&;>Your Subscription > <http://www.listbox.com> > ------------------------------------------- AGI Archives: https://www.listbox.com/member/archive/303/=now RSS Feed: https://www.listbox.com/member/archive/rss/303/21088071-f452e424 Modify Your Subscription: https://www.listbox.com/member/?member_id=21088071&id_secret=21088071-58d57657 Powered by Listbox: http://www.listbox.com
