Handy utilities = Friday Filosofical Finking

[DL Neil]

How do you keep, use, and maintain those handy snippets, functions, 
classes... - units of code, which you employ over-and-over again?


Having coded 'stuff' once, most of us will keep units of code, 
"utilities", which we expect will be useful in-future (DRY principle), 
eg functions to rename files, choose unique back-up/new fileNMs, 
accessing a DB, journalling (logging) start/stop msgs, building specs 
from YAML/JSON/XML/.ini config files (tongue~cheek), etc.

Do you 'keep' these, or perhaps next time you need something you've 
'done before' do you remember when/where a technique was last 
used/burrow into 'history'?
(else, code it from scratch, all over again)

How do you keep them updated, ie if add some new idea, better 
err-checking, re-factor - how to add these 'back' into previous places 
utility is used?
(who wants more "technical debt", plus handling classic 
update/versioning issue)

How do you keep these? eg special file/dir, within IDE, leave in app and 
'remember', on paper, ... If the former, how do you access/import them 
from the various applications/systems?
(Python's import rules and restrictions, change control/version control)


Am interested to hear your tactics; to learn, compare, and contrast...
-- 
Regards,
=dn