Add delete_values() and delete_undef_values() functions

[ptomulik]

Hi,
delete_values() complements delete() for hashes - deletion is based on hash values, not keys,
delete_undef_values() may be used to filter-out "unset" parameters from hash. It then plays nicely with ensure_resource() or create_resources() - see motivating example in README.markdown. I leave this pull request if you consider this function useful enough. Tell me if i've reinvented the wheel.

Regards.

[adrienthebo]

Thank you very much for this contribution! However I have some concerns about how widely used this would be. As a general rule of thumb functions added to stdlib should be usable by 75% of the users of the module, and I'm not sure this meets that criteria. It definitely has merit but I think this function would be better suited as a module. How does this sound to you?

[ptomulik]

I wrote it for apachex module I'm currently developing and thought I could leave this for others in a place where it could persist for longer time. Thought a while about sending feature request but decided to take short cuts and just put the code here. I know, it may be too specific for a general purpose module such as puppetlabs-stdlib in its current form. What if I put few minutes and change this delete_undef_values to delete_values such that the function will delete from Hash/Array all items with given value (so it could serve also my purpose of deleting undefs)? You already have the delete() function in puppetlabs-stdlib, which can handle Hashes (deletion based on keys), and delete_values could complement it in some way?

Update: do you have a tool/method to measure what would be possible use of new functions? I've seen some measures provided in other pull requests (#161) and wonder how were they obtained? Regarding these functions in separate module - of course I can do this, but I'm just one person with no company/foundation behind me and this code would probably disappear in short time or left unmaintained.

[ptomulik]

Added delete_values() - it just complements delete() for Hash type. It appears that I can't handle properly undef's in delete_values(), because undef is converted to empty String when passed as argument to function (#13210, #15329). I leave both functions here. If you think this stuff is of no use, just close this pull request :).

[adrienthebo]

Ah yes, there is the corner case where :undef is magically turned into an empty string. :( Okay, you've convinced me of the necessity of this. I'm going to go through and add some comments on some parts of the implementation that caught my eye.

[adrienthebo]

Did you mean delete_values here?

[ptomulik]

Corrected.

[adrienthebo]

This looks like it's about ready to merge, but before I do that would you be willing to squash these changes down to a single commit?

[ptomulik]

No problem, done.

[adrienthebo]

Did you rebase all of the changes, or just the most recent changes?

[ptomulik]

All.

[adrienthebo]

There we go, when I commented I didn't see that - perhaps github hadn't updated.

[adrienthebo]

summary: merged into master in 5544be9, thanks for the contribution!