docs/wiki/geda-version_control_migration.html

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  15 <h1 class="sectionedit1387"><a name="version_control_migration" id="version_control_migration">Version Control Migration</a></h1>
  16 <div class="level1">
  17
  18 </div>
  19 <!-- EDIT1387 SECTION "Version Control Migration" [1-41] -->
  20 <h2 class="sectionedit1388"><a name="status_quo" id="status_quo">Status Quo</a></h2>
  21 <div class="level2">
  22
  23 <p>
  24
  25 Currently, gEDA uses <acronym title="Concurrent Versions System">CVS</acronym>.  <acronym title="Concurrent Versions System">CVS</acronym> is the “original” version control system used for collaborating on open source projects.
  26 </p>
  27
  28 <p>
  29 Unfortunately, <acronym title="Concurrent Versions System">CVS</acronym> has a number of problems:
  30
  31 </p>
  32 <ol>
  33 <li class="level1"><div class="li"> <acronym title="Concurrent Versions System">CVS</acronym> does not support the concept of patch sets.  That is, it&#039;s very difficult to work out what changes went into <acronym title="Concurrent Versions System">CVS</acronym> together without using dodgy tools like <a href="http://www.cobite.com/cvsps/" class="urlextern" title="http://www.cobite.com/cvsps/"  rel="nofollow">cvsps</a>.</div>
  34 </li>
  35 <li class="level1"><div class="li"> Merging with <acronym title="Concurrent Versions System">CVS</acronym> is painful, especially when there is keyword expansion brokenness such as the <code>Log</code> keyword.</div>
  36 </li>
  37 <li class="level1"><div class="li"> <acronym title="Concurrent Versions System">CVS</acronym> doesn&#039;t support renames preserving history.</div>
  38 </li>
  39 <li class="level1"><div class="li"> The overhead involved in creating and managing a branch in <acronym title="Concurrent Versions System">CVS</acronym> is such that people tend to do one of the following:</div>
  40 <ol>
  41 <li class="level2"><div class="li"> Don&#039;t bother</div>
  42 </li>
  43 <li class="level2"><div class="li"> Use another VCS locally, then export patches, then commit patches to <acronym title="Concurrent Versions System">CVS</acronym>.  This is a big hassle for everyone.</div>
  44 </li>
  45 <li class="level2"><div class="li"> Do II. <strong>and</strong> use a branch in <acronym title="Concurrent Versions System">CVS</acronym>, which is even more hassle, but means people can see the changes in advance.</div>
  46 </li>
  47 </ol>
  48 </li>
  49 <li class="level1"><div class="li"> You can&#039;t do anything in <acronym title="Concurrent Versions System">CVS</acronym> (view logs, view “blame” for a line of code, create diffs to previous versions) without being online &amp; connecting to the repository.</div>
  50 </li>
  51 </ol>
  52
  53 </div>
  54 <!-- EDIT1388 SECTION "Status Quo" [42-1144] -->
  55 <h2 class="sectionedit1389"><a name="what_we_need" id="what_we_need">What We Need</a></h2>
  56 <div class="level2">
  57
  58 <p>
  59
  60 gEDA has a development process that involves a number of people working independently on separate changes.  Some of these are a single changeset hacked together in a few minutes, some involve several major changes and are developed over a matter of months.  Often,  in order to track down a tricky bug, it is necessary for a developer to try and work out what a fellow developer did several months ago.
  61 </p>
  62
  63 <p>
  64 The following features would be deemed desirable in a version control system:
  65
  66 </p>
  67 <ol>
  68 <li class="level1"><div class="li"> Free as in beer as well as free as in speech.</div>
  69 </li>
  70 <li class="level1"><div class="li"> Actively developed/maintained.</div>
  71 </li>
  72 <li class="level1"><div class="li"> Atomic commits (a.k.a. changesets).</div>
  73 </li>
  74 <li class="level1"><div class="li"> All users have their own copy of the history.</div>
  75 </li>
  76 <li class="level1"><div class="li"> Users can make local branches/commits without being logged onto a remote server (“distributed” repository model).</div>
  77 </li>
  78 <li class="level1"><div class="li"> Merge &amp; rename tracking.</div>
  79 </li>
  80 <li class="level1"><div class="li"> Easy to transition to from <acronym title="Concurrent Versions System">CVS</acronym>.</div>
  81 </li>
  82 </ol>
  83
  84 <p>
  85
  86 Using the <a href="http://en.wikipedia.org/wiki/Comparison_of_revision_control_software" class="urlextern" title="http://en.wikipedia.org/wiki/Comparison_of_revision_control_software"  rel="nofollow">comparison matrix at Wikipedia</a>, it looks like only <a href="http://www.selenic.com/mercurial/wiki/" class="urlextern" title="http://www.selenic.com/mercurial/wiki/"  rel="nofollow">Mercurial</a> and <a href="http://git.or.cz/" class="urlextern" title="http://git.or.cz/"  rel="nofollow">git</a> have the features we require.
  87 </p>
  88
  89 <p>
  90 A number of factors militate in favour of using git:
  91
  92 </p>
  93 <ul>
  94 <li class="level1"><div class="li"> Existing experience within the the gEDA development community.</div>
  95 </li>
  96 <li class="level1"><div class="li"> More extensively used by major projects (Linux kernel, X.org X server, OLPC, WINE).</div>
  97 </li>
  98 </ul>
  99
 100 </div>
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