toejough / dictmerge Goto Github PK

the fix for #11 removed the default rule from Pedantic merge, but the correct place for the fix is in BasePedanticMerge.

right now a missing rule will just trigger a key error on an internal dictionary. That sucks.

Just having the MERGE_FUNCTIONS global is ugly. Asking users to override things there is worse.

Leave the default 'merge' function, but create a Merge class which you can customize functions in, and then call via Merge.call.

'create' is misleading - this is really a 'set' function, as it's also the function used to override an already created rule.

suggest 'set_rule' and 'unset_rule' instead of 'create/delete'.

Like key, values

currently there are inconsistent names for the API:

• set/delete rule (not set/unset or create/delete?)
• define/remove type (not define/undefine or add/remove?)

consider updating the API to be:

• create/delete rule
• define/undefine type

It should be possible to allow the user to say "if thing1 quacks and thing2 barks, use the flying-dog merge function". This is even more generic than #1 or #2, and is probably the right way to implement the extend/override functionality.

A generator will be converted to a tuple right now. If it's an infinite generator, it will cause the merge to hang forever. Generators should be caught and treated as scalars when doing a default merge, because it's not possible to know the correct behavior and account for it generically in the default library.

After reflection, while I like the idea of true duck typing, this should not be the default. The rest of python doesn't work that way. The special typing thing could stick around, but make the default be idiomatic python.

When the resolver would be called, throw the KeyConflictError

...and re-raise better error messages. Like if a user passes in an integer instead of a dictionary, or if the resolver is not callable.

What if a user wants to actually combine strings? Or generators? Or custom merge functions for a custom class?

After implementing #1, make it possible to add custom merge functions to the Merge class (as distinct from just overriding existing functions/assignments).

It's reasonable for someone to want a dictionary merge that throws an exception when there are conflicts, or a set merge that does an intersection instead of a union, or a string merge that merges strings, or a generic iterable merge-to-list, or a generic iterable merge-to-set, etc.

Provide these in some sort of 'extras' struct or package, and maybe provide a few pre-customized Merge classes/functions.

Pedantic Merge has rules for default types, even though the default type is not defined in it.