kopia lustrzana https://gitlab.com/sane-project/website
78 wiersze
3.6 KiB
HTML
78 wiersze
3.6 KiB
HTML
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<title>Version Control</title>
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<h2><a name="s4.1">4.1 Version Control</a></h2>
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<p>The SANE standard is expected to evolve over time. Whenever a change
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to the SANE standard is made that may render an existing frontend or
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backend incompatible with the new standard, the major version number
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must be increased. Thus, any frontend/backend pair is compatible
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provided the major version number of the SANE standard they implement
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is the same. A frontend may implement backwards compatiblity by
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allowing major numbers that are smaller than the expected major number
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(provided the frontend really can cope with the older version). In
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contrast, a backend always provides support for one and only one
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version of the standard. If a specific application does require that
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two different versions of the same backend are accessible at the same
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time, it is possible to do so by installing the two versions under
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different names.
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<p>SANE version control also includes a minor version number and a build
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revision. While control of these numbers remains with the implementor
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of a backend, the recommended use is as follows. The minor version is
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incremented with each official release of a backend. The build
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revision is increased with each build of a backend.
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<p>The SANE API provides the following five macros to manage version
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numbers.
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<blockquote>
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<dl>
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<dt><tt>SANE_CURRENT_MAJOR<a name="i6"></tt>:<dd> The value of this macro is the
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number of the SANE standard that the interface implements.
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<p> <dt><tt>SANE_VERSION_CODE<a name="i7">(<i>maj</i>,<i>min</i>,<i>bld</i>)</tt>:<dd>
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This macro can be used to build a monotonically increasing version
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code. A SANE version code consists of the SANE standard major
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version number (<i>maj</i>), the minor version number <i>min</i>,
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and the build revision of a backend (<i>bld</i>). The major and
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minor version numbers must be in the range 0...255 and the
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build revision must be in the range 0...65535.
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<p> Version codes are monotonic in the sense that it is possible to
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apply relational operators (e.g., equality or less-than test)
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directly on the version code rather than individually on the three
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components of the version code.
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<p> Note that the major version number alone determines whether a
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frontend/backend pair is compatible. The minor version and the
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build revision are used for informational and bug-fixing purposes
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only.
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<dt><tt>SANE_VERSION_MAJOR<a name="i8">(<i>vc</i>)</tt>:<dd> This macro returns the
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major version number component of the version code passed in
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argument <i>vc</i>.
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<dt><tt>SANE_VERSION_MINOR(<i>vc</i>)</tt>:<dd> This macro returns the
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minor version number component of the version code passed in
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argument <i>vc</i>.
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<dt><tt>SANE_VERSION_BUILD(<i>vc</i>)</tt>:<dd> This macro returns the
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build revision component of the version code passed in argument
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<i>vc</i>.
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</dl>
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</blockquote>
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