45 lines
1.9 KiB
Markdown
45 lines
1.9 KiB
Markdown
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Versioning
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==========
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### current
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The number of the current interface exported by the library. A current value
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of '1', means that you are calling the interface exported by this library
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interface 1.
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### revision
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The implementation number of the most recent interface exported by this library.
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In this case, a revision value of `0` means that this is the first
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implementation of the interface.
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If the next release of this library exports the same interface, but has a
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different implementation (perhaps some bugs have been fixed), the revision
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number will be higher, but current number will be the same. In that case, when
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given a choice, the library with the highest revision will always be used by
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the runtime loader.
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### age
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The number of previous additional interfaces supported by this library. If age
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were '2', then this library can be linked into executables which were built with
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a release of this library that exported the current interface number, current,
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or any of the previous two interfaces. By definition age must be less than or
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equal to current. At the outset, only the first ever interface is implemented,
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so age can only be `0'.
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For every release of the library `-version-info` argument needs to be set
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correctly depending on any interface changes you have made.
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This is quite straightforward when you understand what the three numbers mean:
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If you have changed any of the sources for this library, the revision number
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must be incremented. This is a new revision of the current interface. If the
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interface has changed, then current must be incremented, and revision reset
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to '0'.
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This is the first revision of a new interface. If the new interface is a
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superset of the previous interface (that is, if the previous interface has not
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been broken by the changes in this new release), then age must be incremented.
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This release is backwards compatible with the previous release.
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