2019Q1 - can't set "doc": var is read-only

[Pietro Cerutti]

On Mar 13 2019, 18:15 UTC, Dan Langille <dan at langille.org> wrote:
>One of our in-house tcl applications is getting an error:
>
>% set sec_comp [$test createComponent security #auto 1 2]
>can't set "doc": var is read-only

Hi Dan,

which version of Tcl are you using? I assume your in-house application 
uses the C interface to Tcl, not just Tcl as a scripting language. If 
that's the case, the error you're seeing is similar to what you'd get if 
you tryied to write to a linked variable defined as read-only:

http://tcl.tk/man/tcl8.7/TclLib/LinkVar.htm

Does this sound familiar?

Alternatively, you might have a trace set up to intercept writes to a 
variable, but that'd need to be either in your code or in some Tcl code 
you're using as a pkg. Example:
http://core.tcl.tk/tcl/artifact/a057a170260b246e?ln=733,740

>In a test environment, I have narrowed it down to something between 
>2018Q4 and 2019Q1
>
>The devs say "something changed" and an internal structure they used to 
>write to can no longer be written to.
>
>Does this ring any bells to folks?

Internal to Tcl? Doesn't make any rings bell here :(

>I'm going to start updating pkgs one by one to see which one breaks it, 
>but wanted feedkback in case this is a known issue.
>
>My searches fail.
>
>Thank you.

Let me know if I can help any further.

-- 
Pietro Cerutti