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by mbp at sourcefrog
import all docs from arch |
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Config specs |
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A *config spec* is a set of instructions for assembling a source tree |
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from separately maintained branches. This is like CVS's "modules" |
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format. Config specs are very commonly used in Clearcase, and the |
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main way of getting a new checkout. |
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Scenarios: |
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* One module is shared by several projects, and it needs to be |
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present in a subdirectory of their trees to build. |
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* There are different commit or stability rules for different parts |
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of a tree. |
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The simplest form is just a specification of branch sources, and where |
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they should be assembled into the tree. Example:: |
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. http://foo.net/fooapp |
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./libbaz http://foo.net/libbaz |
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Normally the entire branch will be placed at this point, but sometimes |
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subdirectory should be selected. Selecting just a single file rather |
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than subdirectory might be problematic because we wouldn't have |
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anywhere to put the control files. |
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Each branch will have a .bzr directory at the top level. Changes on |
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each branch can be pushed back independently. |
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The tool needs to support (and be tested with) nested checkouts. |
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Commands should normally only apply to a single tree, but there might |
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be an option to descend into nested trees. |
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One very important use case is a naive user checking out a tree that |
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happens to use a configspec. This is transparent in cvs, but not at |
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all so in Arch. |
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The ``svn:externals`` mechanism in Subversion works like this. |
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One interesting idea from Aaron is that all branches should be like |
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this: the latest-patch pointer can be generalized to in fact name |
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several patches that should be assembled in subdirectories. A |
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simplest branch names just one, assembled to the base directory. You |
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might want to specify the parent branches for each one as well.... |
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