[THRIFT-162] Thrift structures are unhashable, preventing them from being used as set elements

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 0.10.0
• Component/s: Python - Compiler, Python - Library
• Patch Info: Patch Available
• Assignee: Nobuaki Sukegawa
• Reporter: Esteve Fernandez
• Created: 08/Oct/08 16:35
• Updated: 14/Jun/17 15:48
• Resolved: 27/Nov/15 23:09

Description

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.

Issue Links

• depends upon: THRIFT-301 Add a create() class method for factory-like instantiation
• relates to: THRIFT-3388 hash doesn't work on set/list