22 lines
1.0 KiB
Markdown
22 lines
1.0 KiB
Markdown
# Why are unbound version constraints a bad idea?
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A version constraint without an upper bound such as `*` or `>=3.4` will allow
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updates to any future version of the dependency. This includes major versions
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breaking backward compatibility.
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Once a release of your package is tagged, you cannot tweak its dependencies
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anymore in case a dependency breaks BC - you have to do a new release but the
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previous one stays broken.
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The only good alternative is to define an upper bound on your constraints,
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which you can increase in a new release after testing that your package is
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compatible with the new major version of your dependency.
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For example instead of using `>=3.4` you should use `~3.4` which allows all
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versions up to `3.999` but does not include `4.0` and above. The `~` operator
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works very well with libraries follow [semantic versioning](http://semver.org).
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**Note:** As a package maintainer, you can make the life of your users easier
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by providing an [alias version](../articles/aliases.md) for your development
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branch to allow it to match bound constraints.
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