[En-Nut-Discussion] nutconfig

Duane Ellis duane at duaneellis.com
Tue Jun 24 00:54:42 CEST 2008

harald>> P.S. Not sure if your post was intended for the list.
harald>> Probably your email client specifies a Reply-To header,

Oops - I clicked wrong...

This copy is to the list for the benefit of others.


duane>  The first problem is simple to describe: the enable/disable
scheme used by nutcomponent does not support expressions.

harald> I think it does.

It does - but only at *READ* time and at no other time. I think you have
missed an important point.

Simply put, the LUA code is only when the configuration file is read by
nutcomponent.c - and never again is LUA used.

Effectively - LUA is the 'configuration file parser' - and not much else.

To explain: Today I can say this:

     Feature:  (A) requires (B)

Today in nut configure if I click and disable feature B.
Today A disabled by way of code found in nutcomponent.c

I have no means to say "A requires B and !C" or anything more complicated.
The "requires" item is effectively "group and" - ie: "B and C and D and
E ..."

Adding "NOT" or an "OR" operator -forget parens - that would require:

(1) an expression parser in some form - which does not exist
(2) code that performs that evaluation - which does not exist.


(3) LUA today is not informed that a variable has changed value.
(4) In the present code there is now way to 'evaluate' a block of LUA
code after the file is loaded.


harald>> The usage of Lua had been criticized several times.

Oh, I'm not criticizing lua - My son's WOW game uses it for interface
customization, it is a very interesting package!

haralad> The original eCos Configurator uses tcl, which I'm neither
familiar with

I am familiar with it (+12 years on and off using it)  I know I had to
explain it to many people :-(

In fact a long time ago - one version of the Linux kernel configuration
tool uses Tcl/Tk.

My issue has nothing to do with a choice of script language.


harald>> [lua problems] Luckily this seems to be solved nowadays.

My experience: LUA was fixable, the other GUI stuff just became an utter


duane> The linux kernel configure system ...

harald> I'm not familiar with Linux kernel configuration

Let me see if I can whip up a simple small example.


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