You might be better off trying to avoid having to guess how to process the list objects.

However given that you are creating and executing a command from Tcl_Objs, consider using Tcl_EvalObjv, and instead of checking that the string value looks like an object name just execute the get method on the Tcl_Obj and check if there was an error.

// set up command object array (consider doing this only once in your application)
// I think this is the correct way to initalize a C array to NULLs ??
Tcl_Obj* cmd[3] = {NULL, NULL, NULL};

// second word of command is "get"
cmd[1] = Tcl_NewStringObj("get", -1);

// make sure the "get" does not disappear at an inopportune time.
Tcl_IncrRefCount(cmd[1]);

// need to decrement the reference count (Tcl_DecrRefCount(cmd[1]);)
// just before the cmd[] array goes out of scope to avoid a memory leak

....

// try executing a get method on the current list entry
// if there is a chance the sub element has a zero reference count (unlikely for a list element),
// increment it here (and remember to decrement it later to avoid a memory leak)
cmd[0] = sub_elements[i];
if (TCL_OK == Tcl_EvalObjv(interp, cmd, 0)) {
DO SOMETHING with the result in interp
} else {
TRY SOMETHING ELSE
}

I did not compile or execute this YMMV

Dave B

Le lundi 5 juin 2023 à 17:05:22 UTC+2, clt.to...@dfgh.net a écrit :
> Create the list this way:
> set myList [list 1 2 3 4 [::oo::Obj10 get] foo 10 bar]

@Rich ,
I can't, the goal here is to check each type, so I need to keep the name of the object.

> You might be better off trying to avoid having to guess how to process the list objects.
>
> However given that you are creating and executing a command from Tcl_Objs, consider using Tcl_EvalObjv, and instead of checking that the string value looks like an object name just execute the get method on the Tcl_Obj and check if there was an error.
>
> // set up command object array (consider doing this only once in your application)
> // I think this is the correct way to initalize a C array to NULLs ??
> Tcl_Obj* cmd[3] = {NULL, NULL, NULL};
>
> // second word of command is "get"
> cmd[1] = Tcl_NewStringObj("get", -1);
>
> // make sure the "get" does not disappear at an inopportune time.
> Tcl_IncrRefCount(cmd[1]);
>
> // need to decrement the reference count (Tcl_DecrRefCount(cmd[1]);)
> // just before the cmd[] array goes out of scope to avoid a memory leak
>
> ...
>
> // try executing a get method on the current list entry
> // if there is a chance the sub element has a zero reference count (unlikely for a list element),
> // increment it here (and remember to decrement it later to avoid a memory leak)
> cmd[0] = sub_elements[i];
> if (TCL_OK == Tcl_EvalObjv(interp, cmd, 0)) {
> DO SOMETHING with the result in interp
> } else {
> TRY SOMETHING ELSE
> }
>
> I did not compile or execute this YMMV

@Dave

If I understand , In that way so in Tcl :
foreach obj $myList {
if {![catch {$obj get} value]} {
# Do something
}
} Maybe I'm wrong but in pure Tcl, I would never do like that, It's maybe different in C.
That said
Below my C code :
Tcl_Obj* cmd[2];
cmd[1] = Tcl_NewStringObj ("get", -1);
Tcl_IncrRefCount(cmd[1]);

for (int i = 0; i < count; ++i) {
cmd[0] = sub_elements[i];
Tcl_IncrRefCount(cmd[0]);

if (Tcl_EvalObjv(interp, 2, cmd, 0) == TCL_OK) {
Tcl_DecrRefCount(cmd[0]);
Tcl_ListObjAppendElement(interp, data, Tcl_GetObjResult(interp));
} else {
// Do something...
}
} Tcl_DecrRefCount(cmd[1]);

I’m not sure about myself, it works , but I tested on a list of 20000 items and my performance is bad, my C code is correct ?

Thanks
Nicolas

Nicolas Robert <nicolasrobert.19000@gmail.com> wrote:
> Le lundi 5 juin 2023 à 17:05:22 UTC+2, clt.to...@dfgh.net a écrit :
>> Create the list this way:
>> set myList [list 1 2 3 4 [::oo::Obj10 get] foo 10 bar]
>
> I can't, the goal here is to check each type, so I need to keep the
> name of the object.

Then consider changing your list definition:

set myList [list val 1 val 2 val 3 val 4 obj ::oo::Obj10 val foo val 10 val bar]

Then (in Tcl) you could process something like this way:

foreach {type content} $myList {
switch -exact -- $type {
val { # do something with a value }
obj { # do a [$content get] to get the value, then do something
with the value and the object name }
}
}

A similar 'loop' in C could be crafted but I'm not going to attempt to
type that out here (it would likely contain many syntax errors).

Le mardi 6 juin 2023 à 19:00:41 UTC+2, Rich a écrit :
> Nicolas Robert <nicolasro...@gmail.com> wrote:
> > Le lundi 5 juin 2023 à 17:05:22 UTC+2, clt.to...@dfgh.net a écrit :
> >> Create the list this way:
> >> set myList [list 1 2 3 4 [::oo::Obj10 get] foo 10 bar]
> >
> > I can't, the goal here is to check each type, so I need to keep the
> > name of the object.
> Then consider changing your list definition:
>
> set myList [list val 1 val 2 val 3 val 4 obj ::oo::Obj10 val foo val 10 val bar]
>
> Then (in Tcl) you could process something like this way:
>
> foreach {type content} $myList {
> switch -exact -- $type {
> val { # do something with a value }
> obj { # do a [$content get] to get the value, then do something
> with the value and the object name }
> }
> }
>
> A similar 'loop' in C could be crafted but I'm not going to attempt to
> type that out here (it would likely contain many syntax errors).

Rich,

I do not know the type of my strings before testing them via a loop.
So my loop in Tcl is like this :
foreach content $myList {
if {[string is ...]} {...}
if {[info object isa object ...] {...}
}

I’d like to do the same in C.

Nicolas