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Hi,
So far my Python based QCAlgorithm used PivotPointsHighLow and it all work fine, but it seems that this latest commit (part of the latest 13062 release to master) presents a breaking change as it modifies the name of first constructor parameters (from “length” to "surroundingBarsCount"):
https://github.com/QuantConnect/Lean/commit/67081a8a056eb73a4ac371390358a1389142eae7
As a result backtests started failing with “TypeError : No constructor matches given arguments” error, and I wonder how it might effect my live node soon.
Could you please provide details on how should one handle such breaking changes in advance, before they make their way to live nodes and backtests?
Erez.
Jared Broad
Hey Erez!
Sorry if this was a breaking one for you. Most people just use the relative argument positions, not the named args so it doesn't impact many people.
Generally, we don't make breaking changes; when we do we weigh the number of people impacted; the difficulty of transitioning to the new format, and the importance of the fix. If it only impacts a handful of talented engineers then we are confident they'll be able to make the transition to the new, better API and we lean towards updating it even if there are breaking changes.
We offer the trading firm plan which allows pinning the LEAN version until there is a new “minimum” version of LEAN to run in the cloud. It takes a few seconds longer to start than running the master branch.
We generally don't give advance notice when the impact is in the 10's, but we endeavor to always explain it in the forums when it impacts 100+.
Best,
Jared
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Erez Tison
The material on this website is provided for informational purposes only and does not constitute an offer to sell, a solicitation to buy, or a recommendation or endorsement for any security or strategy, nor does it constitute an offer to provide investment advisory services by QuantConnect. In addition, the material offers no opinion with respect to the suitability of any security or specific investment. QuantConnect makes no guarantees as to the accuracy or completeness of the views expressed in the website. The views are subject to change, and may have become unreliable for various reasons, including changes in market conditions or economic circumstances. All investments involve risk, including loss of principal. You should consult with an investment professional before making any investment decisions.
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