Convenience function for generation of recursive structures #286
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The seed still can't be set by QuickCheck users, but the new Gen constructor is useful for other crates that use QuickCheck only for its Arbitrary trait. Closes BurntSushi#277
When generating recursive structures, users will often use the size of the generator to bound the recursion depth. Dividing the size by the number of sub-structures appears to be a common practice. However, modifying the size of the generator passed to an implementation of `Arbitrary::arbitrary` would also affect the generation of sister structures if not restored after the generation of child nodes. Instead, users can create a new generator instance with the target size. Historically, this would be the only option since public API for setting the size of an existing generator was only introduced recently. This change introduces a convenience function for creating such a generator. The new function makes use of seed from the original generator rather than entropy. In addition to bounding recursive structures, this also allows to re-create those structures based on some initial seed.
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When generating recursive structures, users will often use the size of the generator to bound the recursion depth. Dividing the size by the number of sub-structures appears to be a common practice. However, modifying the size of the generator passed to an implementation of
Arbitrary::arbitrarywould also affect the generation of sister structures if not restored after the generation of child nodes. Instead, users may choose to create a new generator instance with the target size.The new function makes use of seed from the original generator rather than entropy. In addition to bounding recursive structures, this also allows to re-create those structures based on some initial seed.
This PR is based on #278 (in order to make use of
from_seed).