Am 16.01.2024 um 16:17 schrieb Ralf Fassel:

| Can I (efficiently) access nested dicts with the C API?

I would say 'yes', since in nested dicts the values are themselves just
dicts instead of plain... well... 'values'. Haven't tried that myself, though.

I confirm that this works: nested dicts from C.
There is no buildin for it, so it should be programmed manually:

TCL_OBJ * subdict;

if (TCL_OK == Tcl_DictObjGet(interp, dictPtr, keyPtr, subdict)
&& TCL_OK == Tcl_DictObjGet(interp, subdict, keyPtr, valuePtrPtr) )

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* Alexandru <[email protected]>
| I have some C functions that perform fast operations on lists of numbers.
| Until now, I transfer Tcl data in the shape of lists to those C functions.
| In some cases the Tcl data is stored in dictionaries so I run some Tcl
| loops over the Tcl dict, put the needed data into lists and finally
| pass the lists to the C function.
| Since performance is paramount, I'm thinking that the above method might not be the fastest.
| If I would directly pass the Tcl dict to the C function, would that be faster?

Not copying data sounds always faster to me...

https://www.tcl.tk/man/tcl8.6/TclLib/DictObj.html

lists the C interface to dicts. Basically you get the TclObjs for the
keys and/or values in the dict. You would then call Tcl_GetIntFromObj()
on the value ptr.

| What if the Tcl dict is "nested" so there are multiple keys that lead to a value?

You would need some information on the nesting depth, since the value
has no "I'm a dict" label attached. You could check whether Tcl_GetIntFromObj(valueptr) is successful and if not, try to use it as multiple-level dict.

| Can I (efficiently) access nested dicts with the C API?

I would say 'yes', since in nested dicts the values are themselves just
dicts instead of plain... well... 'values'. Haven't tried that myself, though.

HTH
R'

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* Harald Oehlmann <[email protected]>
| Am 16.01.2024 um 16:17 schrieb Ralf Fassel:
| > | Can I (efficiently) access nested dicts with the C API?
| > I would say 'yes', since in nested dicts the values are themselves
| > just
| > dicts instead of plain... well... 'values'. Haven't tried that myself, though.

| I confirm that this works: nested dicts from C.
| There is no buildin for it, so it should be programmed manually:

| TCL_OBJ * subdict;

| if (TCL_OK == Tcl_DictObjGet(interp, dictPtr, keyPtr, subdict)

I *think* that needs to be

Tcl_DictObjGet(interp, dictPtr, keyPtr, &subdict)

since Tcl_DictObjGet() takes a TclObj** as last parameter.

R'

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