Struct being converted

[mauricioszabo]

On Hamster's Hamster.from documentation, there's no mention that Struct will be converted to a hash, and indeed it is really strange:

class SomeClass < Struct.new(:foo, :bar); end
obj = SomeClass.new(10, 20)
irb(main):014:0> Hamster.from({obj: obj})
# => Hamster::Hash[:obj => Hamster::Hash[:bar => 20, :foo => 10]]

The problem is that SomeClass is not a hash, it is a struct, so this will fail:

a = {obj: SomeClass.new(10, 20)}
b = {obj: SomeClass.new(10, 20)}
Hamster.to_ruby(Hamster.from(a)) == b
# => false

# While these are true:
a == b
Hamster.to_ruby(Hamster.from(a)) == Hamster.to_ruby(Hamster.from(b))

The problem is that Hamster.from loses the struct information, so it's impossible to get back the original object, and the documentation doesn't mention anything.

[dubek]

I looked at the history and it seems that this behaviour was deliberately added in commit e7a8f12 (includes tests-cases). However, as you mention, the documentation doesn't mention this one-way behaviour: Hamster.from converts Struct to Hamster::Hash but Hamster.to_ruby doesn't (cannot) convert it back.

A PR with documentation changes for Hamster.from and Hamster.to_ruby would be appreciated...

[alexdowad]

Hmm. Don't remember what the reasoning behind this was. ☹️

…

On Wed., Jul. 24, 2019, 8:57 a.m. Dov Murik, ***@***.***> wrote: I looked at the history and it seems that this behaviour was deliberately added in commit e7a8f12 <e7a8f12> (includes tests-cases). However, as you mention, the documentation doesn't mention this one-way behaviour: Hamster.from converts Struct to Hamster::Hash but Hamster.to_ruby doesn't (cannot) convert it back. A PR with documentation changes for Hamster.from and Hamster.to_ruby would be appreciated... — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#249?email_source=notifications&email_token=AAIESX7WJ2RIQCAKFCUNWD3QA74LZA5CNFSM4IF3X5JKYY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOD2VLY2Y#issuecomment-514505835>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAIESX2QJ3M2RRGTRWUUP4DQA74LZANCNFSM4IF3X5JA> .

[mauricioszabo]

I saw that it was deliberate too, but I think that it probably violates the principle of less surprise, as it looses information on the conversion (something that don't happen if I try to convert only hashes, arrays and sets).

I would vote for another solution on Struct's conversion, but if it's not possible an update on documentation would be great too :)