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From: Eric Blake <ebb9 AT byu DOT net>
Subject:  Re: Merits of ClearCase
Date: Mon, 14 Dec 2009 16:54:44 +0000 (UTC)
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Marc Girod <marc.girod <at> gmail.com> writes:

> Renaming a label type is an O(0) operation.

There's no such thing as O(0).

> It doesn't depend on the number of labels of that type applied.

Just because renaming a label is O(1) doesn't make applying the label in the 
first place O(1).  I want a VCS that tracks changesets.  In other words, if I 
can point to a given file that changed on a certain date, then I want my VCS to 
find all other files that were changed at the same time.  Atomic renames mean 
nothing if you don't have atomic commits in the first place.  And yes, you can 
get changeset information in clearcase, just like you can get changeset 
information from CVS, but in both of those systems, it costs some painful 
overhead to reverse-engineer, and the cost is most certainly not O(1).  Or you 
can use modern VCS, git being my favorite, but several others will do, where 
obtaining the information about a changeset is O(1).

And to keep this cygwin-related: yes, it is true that one of the reasons I 
maintain the cygwin port of git because it is open source, while there is zero 
chance of clearcase ever being ported to cygwin because it is proprietary.  But 
it is more than just the free source aspect - one of the reasons I maintain 
git, even though I'm forced to interface with clearcase at my work, is because 
the concept of atomic changesets is such a fundamental improvement over any 
features that clearcase may claim to offer amidst all its bloat.  I find that I 
am much more productive if I manage my own work in git, then convert it to 
clearcase at the end of the day, rather than suffering through the slowness of 
clearcase throughout the day.  And the fact that a VCS distributed with cygwin 
will understand cygwin paths and interact well with cygwin ptys, while closed-
source behemoths like clearcase do not, is another argument in favor of a 
cygwin VCS solution.

Finally, I feel justified continuing to argue the merits of programs offered as 
part of the cygwin distribution on the cygwin mailing list, but I don't think 
it is appropriate to argue the merits of proprietary non-cygwin programs on the 
cygwin list.  This is for the same reason that we tell people to take their 
questions about 'gcc -mno-cygwin' to an appropriate list - this mailing list is 
for promoting the use of cygwin, not for promoting the use of non-cygwin.  If 
you insist on touting clearcase, at least move the conversation to the talk 
list.

-- 
Eric Blake




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