[SPARK-9093][SparkR] Fix single-quotes strings in SparkR

[yu-iskw]

[SPARK-9093] Fix single-quotes strings in SparkR - ASF JIRA

This is the result of lintr at the rivision:011551620faa87107a787530f074af3d9be7e695
[SPARK-9093] The result of lintr at 011551620faa87107a787530f074af3d9be7e695

[yu-iskw]

@shivaram Could you review it when you have time? Thanks!

[SparkQA]

Test build #37486 has finished for PR 7439 at commit 61c391e.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[sarutak]

Should we insert a white space into both sides of = ?
Could you fix this as well?

[yu-iskw]

Maybe. But personally, I think fixing it would be better with another issue. Since we haven't discussed the validation rule for the spaces for parameters yet.

[sarutak]

I've left minor comments. Otherwise, LGTM.

[yu-iskw]

@sarutak Thank you for reviewing it!

[shivaram]

@yu-iskw FWIW we already have an (admittedly unwritten) style rule of putting space around both sides of =. We discussed this I think before SparkR was merged and its also a part of Hadley's style guide.
http://adv-r.had.co.nz/Style.html

BTW does lintr catch these or not ?

[yu-iskw]

@shivaram Oh, sorry. I had fogotten.. Hmm, it seems that lintr couldn't catch these warnings. I'll check and get back to you.

Anyway, I'll fix them as @sarutak suggested.

[shivaram]

Actually it comes up in a few more places but mostly in example code I guess
You can see this by running grep -r "[^ ]=[^ ]" $SPARK_HOME/R/pkg/R

[yu-iskw]

@shivaram I have just experimented the infix operator warnings at function's optional parameters. According to the result, it seems that lintr can't catch them which are optional parameters.
https://gist.github.com/yu-iskw/be8398c17dc48f82c293

[yu-iskw]

After all, I think it would be better to deal with the spaces problems on another issue. Because there is no linter about that, it is not easy to validate them now. Plus, we should focus on getting rid of the warnings about single-quotes strings on this PR.

[sarutak]

Alright, let's focus on the single-quote string literals on this PR.
For now, I'm merging this into master and branch-1.4 and then, we can focus on another one.
@yu-iskw , thanks for your contribution!

[sarutak]

I got merge conflicts to branch-1.4. because #7395 is not merged into branch-1.4.
After #7395 is backported, we can easily backport this change too.
Feel free to open PRs for them.

[shivaram]

Yeah backporting style improvements didn't seem very important to me. The only reason to backport them would be to avoid conflicts for other backport PRs -- Feel free to open a new JIRA / PRs if you think it'll make things easier in the future.