Prompt changed based on when dspy.settings.configure(lm=lm) is executed.

[mikeedjones]

If you configure the LM (dspy.settings.configure(lm=lm)) before initializing your modules you get a different prompt to if you configure your LM after initializing your modules.

    dspy.settings.configure(lm=lm)
    pot = ChainOfThought(BasicQA)

Adds "reasoning" to the output signature.

    pot = ChainOfThought(BasicQA)
    dspy.settings.configure(lm=lm)

Adds "rationale" to the output signature.

Think its because the dspy.settings.lm is referenced in ChainOfThought.__init__:

        # Add "rationale" field to the output signature.
        if isinstance(dspy.settings.lm, dspy.LM):
            extended_signature = signature.prepend("reasoning", rationale_type, type_=str)
        else:
            extended_signature = signature.prepend("rationale", rationale_type, type_=str)

Maybe something to flag in migration docs or just to be aware of before this logic is removed when dsp.LM is removed.

[okhat]

Very interesting, thanks for the catch @mikeedjones ! Good reason to migrate fully in 2.6 soon

[okhat]

Since this could be fairly annoying, I'm thinking the following: if we don't release 2.6 (which deletes old clients) within a very short time, we should make them only work if dspy.configure(legacy=True) before any DSPy usage. Once legacy is turned on, it cannot be turned off, i.e. you cannot mix and match 2.5 and 2.4 style DSPy.

That way, we can greatly simplify the if statement causing this issue.

[mikeedjones]

As far as I can tell this change only affects ChainOfThought and Predict - could there be a ChainOfThoughtv2 or something for the change over period?