Matlab - How to check the existence of a handle -

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is there way check if handle exists or not? like: if didnt declare handle, want 0 output , else 1.

i tried ishandle,isvalid,isfield,isempty don't work on "non-existent field" receive error if didnt declare handle.. "reference non-existent field 'sp'."

if try "exist name" function works variables not handles

so:

handle.a=figure; exist handle.a;

returns 0

while

handle.a=figure; a=handle.a; exist

returns 1

but i'm looking for:

handle.a=figure; exist handle.a

ans=1

%without setting handle: exist handle.a

ans=0

i hope post understandable. thank help! klaus

let me rephrase: assigning handle field of structure. want test whether there valid handle in field, , guard against wrong: (1) there's no field, (2) it's empty, (3) it's array instead of scalar, (4) it's not handle, (5) it's not valid handle.

thus:

tf = isfield(handle,'a') && isscalar(handle.a) && ishandle(handle.a);

of course, if know of conditions can never occur, can drop respective tests.


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