Allow the usage of lambdas for InputPort default values
#3465
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Ah, I see @chrisjsewell has me beat by 1 minute ;-) |
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ltalirz
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This is made possible by upgrading `plumpy` to version `0.14.3`. This functionality is useful to define defaults that should change at each invocation, for example the generation of a seed. However, it also provides a way to avoid the issues that arise when defining a default to be an instance of a `Node`. Since a node instance is always regarded as a mutable type by python, regardless whether it is stored or not, it can cause unexpected behavior. For example when the node appointed to the default value of a port is deleted in the database, the memory instance remains and points to a no longer existing database row. The next time it is accessed an exception will be thrown. Using a lambda avoids this problem.
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Fixes #1604
This is made possible by upgrading
plumpyto version0.14.3. Thisfunctionality is useful to define defaults that should change at each
invocation, for example the generation of a seed. However, it also
provides a way to avoid the issues that arise when defining a default to
be an instance of a
Node. Since a node instance is always regarded asa mutable type by python, regardless whether it is stored or not, it can
cause unexpected behavior. For example when the node appointed to the
default value of a port is deleted in the database, the memory instance
remains and points to a no longer existing database row. The next time
it is accessed an exception will be thrown. Using a lambda avoids this
problem.
Edit: this will also address #2515 and #3143 indirectly. It will still require users to replace mutable defaults with lambdas. Therefore I prefer to close them in a separate PR where the
InputPortconstructor implementation will warn when mutable values are specified for the port's default