topic Re: Scientific notation in entity handles in Visual LISP, AutoLISP and General Customization Forum

Scientific notation in entity handles

Anonymous — Sun, 29 Aug 2021 15:45:38 GMT

Hi.

This question exists on the forums https://forums.autodesk.com/t5/vba/handles-getting-modified-when-put-in-excel/m-p/1865322#M79968
which details the problem with hex handles being exported and converted to scientific notation.

My problem is not exporting to excel, but directly in autocad.

(vl-prin1-to-string 124E4) (vl-princ-to-string 124E4)

I store a structure on a DXF record in an xdictionary on an entity.
These structures have an entity handle reference.

The structure is a list, or list of lists that are stored as a string in the record, and (read) back into the lisp runtime to be manipulated and then stored back as a string.

I have to do a (vl-prin*) to put the structure into a string and be able to read it back.

My question is: can I set the lisp reader to ignore that conversion for the function in question?

Do I even have access to the lisp reader in autolisp?

Thnaks

Re: Scientific notation in entity handles

Sea-Haven — Sun, 29 Aug 2021 23:46:18 GMT

1st hex is 2 characters 124E4 is only 5 not 6 ? If you export as "ABAEE4" in csv file will work you need to make the string a double "\"ABAEE4\"" so it appears as a string.

Re: Scientific notation in entity handles

Anonymous — Mon, 30 Aug 2021 07:43:51 GMT

Thanks for the reply; but the problem is a little more fundamental than that.

(setq A '(1 "just" "a" "list" "124E4") ;; even "12E44" and so forth A1 (cons 1 (vl-princ-to-string A)) A2 (read (cdr A1)))

A2 now holds a converted SN symbol.

If I was to build the stringify and read functions using (vl-prin1-to-string), the read back structure breaks in interesting ways since the prin1 function is compatible with (load) function, and not (read) function.
I have discovered why prin1 is not useful, but call me stumped if I could find the reason in the reams of code I have. It just breaks something even more important.

My last resort is handling entity handles differently, as you suggest, breaking the notational representation by maybe replacing 'E' with '-' in those string handles passing through the structure handler functions.

But come on, do I not have access to the reader?

Re: Scientific notation in entity handles

Sea-Haven — Mon, 30 Aug 2021 08:33:14 GMT

(handent handle)

Re: Scientific notation in entity handles

hak_vz — Mon, 30 Aug 2021 09:05:30 GMT

(setq A (list 1 "just" "a" "list" (strcat "\"" "124E4" "\"")) A1 (cons 1 (vl-princ-to-string A)) A2 (read (cdr A1)) )

A --> (1 "just" "a" "list" "\"124E4\"") A1 --> (1 . "(1 just a list \"124E4\")") A2 --> (1 JUST A LIST "124E4")

Re: Scientific notation in entity handles

Anonymous — Mon, 30 Aug 2021 09:09:11 GMT

Thank you.

Re: Scientific notation in entity handles

hak_vz — Mon, 30 Aug 2021 09:12:59 GMT

Not a problem. I hope you understand how it works.

Re: Scientific notation in entity handles

Anonymous — Mon, 30 Aug 2021 09:29:28 GMT

Oh yes, quoting the contents of the string redirects the reader to dump a string, not a symbol it believes is a representation of scientific notation.
I missed that obvious nugget.