Use common datetime part when naming output files across all formats

[jdvorak001]

Describe your changes

Fix #2901

• the datetime is fetched just once
• it is then passed to the functions that start the output files, always as arg1

A question: Shouldn’t we put ’T’ between the date and the time instead of the dash? That way we’d be consistent with the ISO 8601 standard.

What is your pull request about?

• Bug fix
• Improvement
• New feature (adds functionality)
• Breaking change (bug fix, feature or improvement that would cause existing functionality to not work as expected)
• Typo fix
• Documentation update
• Update of other files

If it's a code change please check the boxes which are applicable

• For the main program: My edits contain no tabs, indentation is five spaces and any line endings do not contain any blank chars
• I've read CONTRIBUTING.md and Coding_Convention.md
• I have tested this fix or improvement against >=2 hosts and I couldn't spot a problem
• I have tested this new feature against >=2 hosts which show this feature and >=2 host which does not (in order to avoid side effects) . I couldn't spot a problem
• For the new feature I have made corresponding changes to the documentation and / or to help()
• If it's a bigger change: I added myself to CREDITS.md (alphabetical order) and the change to CHANGELOG.md

[drwetter]

Hi @jdvorak001 ,

thanks for taking action!

A question: Shouldn’t we put ’T’ between the date and the time instead of the dash? That way we’d be consistent with the ISO 8601 standard.

How it should be like, is a matter of YMMV ;-) At the moment in this PR I wouldn't vote for that. The format could be configurable though some time in the future.

Remarks:

• datetime_filename_part is too long and makes the code more difficult to read.
• Don't capitalize the variables, unless they are global VARS (which need to declared in the very beginning).

[jdvorak001]

Thanks for the comments on the style, I’ve adapted. However, I find datetime a bit too vague, so I’m suggesting datetime_started.

[drwetter]

looks obvious. If we want to do hair splitting that's not accurate as the date when you call the function date and not when the scan is started 😃 . It's actually more or less shortly before the files are created.

Two points are still open: lets_roll() doesn't have a declaration with local . Then the current var is filled with a value in the middle of the nowhere. Either we use a date stamp when the variable is defined -- which is fine and provides better readability -- or shortly before it's being used. See comment

[drwetter]

Merged this into another PR (#2904), thus closing.

[jdvorak001]

Ok, great you had some use for this. I was laid down by a disease, unable to follow.