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Posted to commits@cassandra.apache.org by "Brad Schoening (Jira)" <ji...@apache.org> on 2023/11/29 23:00:00 UTC
[jira] [Commented] (CASSANDRA-18914) Refactor and separate CQLSH 'Shell' repl class
[ https://issues.apache.org/jira/browse/CASSANDRA-18914?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17791363#comment-17791363 ]
Brad Schoening commented on CASSANDRA-18914:
--------------------------------------------
I've found the challenge here is refactoring the default parameter values which are often set in three places, .cshrc, read from the command line and in the Shell __init__ constructor.
> Refactor and separate CQLSH 'Shell' repl class
> ----------------------------------------------
>
> Key: CASSANDRA-18914
> URL: https://issues.apache.org/jira/browse/CASSANDRA-18914
> Project: Cassandra
> Issue Type: Improvement
> Components: CQL/Interpreter
> Reporter: Brad Schoening
> Assignee: Brad Schoening
> Priority: Normal
>
> CQSH's core Read-Eval-Print-Loop (REPL) class *Shell* implements the Python stdlib *Cmd* framework for writing line-oriented command interpreters. It is the core of CQLSH. While a subclass of _Lib/cmd.py,_ its currently commingled with command line parsing into a jumbo _cqlshmain.py_ file. It's role as a class is easily missed as there is only one line defining it and one line invoking it.
> This Jira will separate the class Shell (inherited from cmd.Cmd) into its own class file, shell.py.
> Benefits:
> * size - excessively large files can be ugly, and cqlshmain is almost 2400 lines.
> * separation of concerns - argument parsing and interactive interpreters are very different responsibilities. Code is improved and more reusable when unrelated behavior is in separate source file.
> * clarity - reading cqlshmain, its currently not obvious that 75% of the code is implementing interfaces in the cmd.Cmd library class. There is currently no class comment explaining how the Shell class is implemented.
> New state:
> * cqlshmain.py – existing startup and argparse code
> * shell.py – existing Shell REPL for CQL
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