lookup_every_key.md

Lookup Every Key

Problem

On structures like maps or arrays there are different possibilities which keys are looked up in the KeySet and which are simply iterated.

Without any guidelines, applications would provide arbitrary inconsistent behavior.

Constraints

Assumptions

• Applications that have good reasons to ignore the guidelines (e.g. they only read from one namespace), are allowed to do so.

Considered Alternatives

• only lookup the roots and then iterate over the next keys
• let the applications do what they want without any guideline

Decision

Every key that an application wants to use, must be looked up with ksLookup using a cascading lookup key.

Rationale

• very simple rule, easy to understand, easy to follow
• provides consistent behavior (spec is always honored)
• ksLookup is quite cheap as it has only a few simple loops, only one allocation and less then 10% of CPU time in profiling, even in very simple applications with many lookups.

Implications

Needs some helper functions or support in bindings as it is a bit tricky to implement e.g. for arrays.

Related Decisions

• Arrays

Notes