From: Tupshin Harper Date: Tue, 19 Apr 2005 23:38:32 GMT Subject: Re: Darcs and git: plan of action Message-ID: <42659678.9090605@tupshin.com> In-Reply-To: <1113952916.29444.60.camel@orca.madrabbit.org> Ray Lee wrote: >it allows regular expressions for the match and replace, which means >multiple unique tokens could change atomically. (Does anyone actually >*use* regexes? Sounds like a cannon that'd be hard to aim.) > > Yes, and replace patches need to be used very carefully. >Regardless, I only care about code, not free text. If it's in a language >that doesn't do some use-'em-as-you-need-'em duck typing spiel >(pythonfile) already has those tokens somewhere in them. And I bet that if >*you* looked at that file, you could tell if it was a replace or a mere >textual diff. Am I wrong? > > Yes. See my hello world example from my last email. > >Unless I'm missing something, the darcs replace patch can already do the >wrong thing. > Yes, depending on how you define wrong. Darcs replace is fully predictable, and poorly chosen replaces can lead to incorrect results after future patches are applied. >If I do a replace patch on a variable introduced in a local >tree, then do a darcs replace on it before committing it to a shared >repository, and coder B introduces a variable of the same original name >in my copy, then there's a chance that the replace patch will >incorrectly apply upon his newly introduced variable. No? > > Absolutely correct, and the exact reason why replace patches need to be used *very* selectively. > > >>It's provable that you can not. >> >> > >I'm still not seeing the problem, at least when it comes to ANSI C. > >Ray > > See hello world example in my other email. You can argue that it is an existing problem in darcs, but really, it just points out the fact that a computer is *incapable* of knowing whether it is safe to use a replace patch based on a diff because replace patches are dangerous if not used intelligently. -Tupshin