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Document the rationale for argXpath matching.

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Will Thompson 2010-11-21 17:01:25 +00:00
parent b3fa6eff0d
commit b4ae31b982
1 changed files with 22 additions and 10 deletions
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32
doc/dbus-specification.xml
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@ -3604,16 +3604,28 @@
<row>
<entry><literal>arg[0, 1, 2, 3, ...]path</literal></entry>
<entry>Any string</entry>
<entry>Argument path matches provide a specialised form of wildcard
matching for path-like namespaces. As with normal argument matches,
if the argument is exactly equal to the string given in the match
rule then the rule is satisfied. Additionally, there is also a
match when either the string given in the match rule or the
appropriate message argument ends with '/' and is a prefix of the
other. An example argument path match is arg0path='/aa/bb/'. This
would match messages with first arguments of '/', '/aa/',
'/aa/bb/', '/aa/bb/cc/' and '/aa/bb/cc'. It would not match
messages with first arguments of '/aa/b', '/aa' or even '/aa/bb'.</entry>
<entry>
<para>Argument path matches provide a specialised form of wildcard
matching for path-like namespaces. As with normal argument matches,
if the argument is exactly equal to the string given in the match
rule then the rule is satisfied. Additionally, there is also a
match when either the string given in the match rule or the
appropriate message argument ends with '/' and is a prefix of the
other. An example argument path match is arg0path='/aa/bb/'. This
would match messages with first arguments of '/', '/aa/',
'/aa/bb/', '/aa/bb/cc/' and '/aa/bb/cc'. It would not match
messages with first arguments of '/aa/b', '/aa' or even '/aa/bb'.</para>
<para>This is intended for monitoring “directories” in file system-like
hierarchies, as used in the <citetitle>dconf</citetitle> configuration
system. An application interested in all nodes in a particular hierarchy would
monitor <literal>arg0path='/ca/example/foo/'</literal>. Then the service could
emit a signal with zeroth argument <literal>"/ca/example/foo/bar"</literal> to
represent a modification to the “bar” property, or a signal with zeroth
argument <literal>"/ca/example/"</literal> to represent atomic modification of
many properties within that directory, and the interested application would be
notified in both cases.</para>
</entry>
</row>
</tbody>
</tgroup>