[Lilypond-auto] [LilyIssues-auto] [testlilyissues:issues] #5906 Copy alist instead of deep copy on Grob clone

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• labels: --> Fixed_2_21_1
• status: Started --> Fixed
• Patch: push -->
• Comment:

commit a456a5946c21cb63c64640a758e7faf829d98fa2
Author:     Han-Wen Nienhuys <address@hidden>
AuthorDate: Mon Apr 13 20:57:51 2020 +0200
Commit:     Han-Wen Nienhuys <address@hidden>
CommitDate: Sun Apr 19 09:59:34 2020 +0200

    Copy alist instead of deep copy on Grob clone

    On the MSDM score, ly_deep_copy takes 1.58% of runtime according a
    gprof. Removing it shows a consistent 1.4% improvement in user
    time.

    The deep copy was introduced together with the separation of object
    properties and value properties. This is because the Grob substition
    did a recursive rewrite of the entire mutable alist, and the
    equivalent for value (ie. non-object) properties is to do a deep copy.

    The deep copy does not really solve a problem, because the reader
    calling get_property cannot distinguish grob-local values from
    immutable, shared values. The sort of modification that a deep copy
    protects against would modify the shared data in this case, leading to
    bugs.

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[issues:#5906] Copy alist instead of deep copy on Grob clone

Status: Fixed
Labels: Fixed_2_21_1
Created: Mon Apr 13, 2020 06:58 PM UTC by Han-Wen Nienhuys
Last Updated: Sun Apr 19, 2020 06:49 AM UTC
Owner: Han-Wen Nienhuys

https://codereview.appspot.com/561640045

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