# `Feel.Extension.Camunda.Overloads`
[🔗](https://github.com/FeeJai/BDM/blob/feel-v0.1.0/apps/feel/lib/feel/extension/camunda/overloads.ex#L1)

The signatures that Camunda gives to functions of DMN 1.6 (D-81).

The function of DMN 1.6 runs first. Each of these answers only an error of it, or a number of arguments it does not
take, and says `:next` when the arguments are not its own (`Feel.Builtin.Function.with_overloads/2`, D-81), so a call
that DMN 1.6 answers gives what it gave.

| Call | Camunda |
| ---- | ------- |
| `number("1,500", ",")` | the text with the grouping separator taken out, as `number(from, grouping separator, null)` |
| `date and time(date and time, timezone)` | the same instant at the zone: `Z`, an offset or the id of a zone |
| `string join(list, delimiter, prefix, suffix)` | the joined text with the prefix before and the suffix after |
| `get value(context, keys)` | the entry at the path of the keys, `null` if there is none or the keys are none |
| `context put(context, keys, value)` | the entries of the path that are not there are made |
| `substring(string, start position, length)` | a length past the end is the rest of the string |

Three of them answer a call that DMN 1.6 refuses by what it asks for, and are deviations from the TCK where it has a
case; `apps/bdm_tck/test/fixtures/tck/deviations/camunda_overloads.txt` names each, with the reason.

**`date and time(date and time, timezone)` does not take a date and time without a zone.** It has no instant, and
Camunda reads it in the zone of the machine it runs on, so the result depends on the machine: the example of its
documentation, `date and time(@"2020-07-31T14:27:30", "Z")` is `12:27:30Z` where the zone is Berlin in summer. Here that
is the error of DMN 1.6.

**Nor does it take an instant that its zone cannot write.** Where the clocks go back, a local time happens twice and the
library reads it as the earlier (`Feel.Value.Zone`), so the later of the two instants has no `date and time` in that
zone and is the error of DMN 1.6, and not the other instant.

**`context put` makes the entries that are not there, and only those.** A key of the path that is an entry which is not
a context stays the error of DMN 1.6, as the TCK has it (`1146#nested009`).

It is `:camunda_overloads`, and part of `:camunda`.

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*Consult [api-reference.md](api-reference.md) for complete listing*