I'd still go with the one @shirleyquirk posted. That version will only do it
for tables, and not arbitrary values, saving you from the issue that the C++
code had. Compare this:
proc `[]`[A, B, C](t: var Table[A, Table[B, C]], key: A): var Table[B, C] =
t.mgetOrPut(key, initTable[B, C]())
var nested: Table[string, Table[string, Table[string, int]]]
nested["this"]["works"]["fine"] = 42
#echo nested["this"]["doesn't"]["work"] # Will throw an exception about the
key not being found
Run
To this, which has similar behaviour to the C++ version which silently inserts
keys:
var nested: Table[string, Table[string, Table[string, int]]]
nested["this"]["works"]["fine"] = 42
discard nested["now"]["this"]["works"] # Adds a default int to the key
echo nested["now"]["this"].len # Now there is something in the
"this" table
echo nested["now"]["this"].hasKey("works") # And the works key have been
silenly added
echo nested["now"]["this"]["works"] # With the default value of an
int, which is 0
Run
The first version will still shadow-add table entries to the subtables if you
do something like `echo nested["a"]["couple"]["keys"]`, but you could always
also create a procedure like:
proc hasKey[A, B, C](t: Table[A, Table[B, C], k: A): bool = t.hasKey(k) and
t[k].len != 0
Run
To make `hasKey` behave a bit more like "has key with useful data".
