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https://issues.apache.org/jira/browse/THRIFT-162?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12638237#action_12638237
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Esteve Fernandez commented on THRIFT-162:
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You're completely right, somehow I mixed Java and Python. It's advisable to
define a custom hashCode method if you define a equals in Java, but this
doesn't apply to Python, unless objects are immutable.
I'm using a Thrift structure to wrap uuids (as two 64 bit integers), and I
needed to use them as set elements. Do you think it would be desirable to add a
returnImmutable method to Thrift structures so they can be used as set elements
and dictionary keys?
> Thrift structures are unhashable, preventing them from being used as set
> elements
> ---------------------------------------------------------------------------------
>
> Key: THRIFT-162
> URL: https://issues.apache.org/jira/browse/THRIFT-162
> Project: Thrift
> Issue Type: Bug
> Components: Compiler (Python), Library (Python)
> Reporter: Esteve Fernandez
> Priority: Minor
> Attachments: thrift_py_hash.patch
>
>
> Let Foo be a Thrift structure:
> struct Foo {
> 1: i32 bar
> }
> If you want to use it properly as a set element or a as a dictionary key, the
> autoegenerated Python code will complain about not being hashable:
> >>> f1 = Foo()
> >>> f1.bar = 1
> >>> f2 = Foo()
> >>> f2.bar = 1
> >>> f1 == f2
> True
> >>> set([f1]) & set([f2])
> set([])
> >>> d = {}
> >>> d[f1] = 2
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> TypeError: unhashable instance
> Since Thrift structures already implement __eq__ and __ne__, they should
> implement __hash__ as well. The attached patch tries to mimic the behaviour
> of the Java compiler, including a HashCodeBuilder class written in Python.
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