Re: Coloring error and warning messages in the gui console

[Daniel J Sebald]

On 05/09/2017 02:35 PM, Torsten wrote:
> I am currently working on possible ways to color error and warning
> messages in the gui console window. The unix based terminal offers
> filters for highlighting matched "hotspots". Unfortunately, the elements
> painted for highlighting lead to ugly artefacts when scrolling.
> Consequently, this filter method is currently only used for underlining
> clickable links (files for opening in the editor or urls) when the mouse
> cursor is hovering over them.
>
> For the text colors of error and warning messages I would like to insert
> suitable escape sequences into the message strings as implemented in the
> patch attached to comment #9 of bug #35619
> (https://savannah.gnu.org/bugs/?35619#comment9)
> Before pushing this patch, I would like to know whether there are any
> objections against changing one of octaves core files (error.cc) only
> for "cosmetic" reasons.
>
> Best,
> Torsten

Thanks for asking Torsten.  I looked at the patch and I object to this 
one on the basis that it implies the core code is doing something GUI 
specific, i.e., assigning some color to the errors.  Is that something 
that should be done?  I've been against inter-mixing GUI details into 
core code from the start, for multiple reasons.  (I drafted a response 
to one of Rik's emails a couple weeks back, but hadn't sent it... I will 
follow up this email.)

The proper way to do this, as I see it, is for the core to allow some 
routine to access the previous error(s), whether that is a function or 
some type of script command.  (Unfortunately, there has always been 
lacking the simple method of calling a script from the GUI and getting 
an octave_value_list in return.)  That is, when there is an error, the 
core should have a log of what happened (a unique error message or 
classification) and the line number and file where it happened.  There 
should also be a list of available error messages, for which the GUI can 
assign the color scheme however it wants.  The steps would be:

1) GUI recognizes error occurred
2) GUI inquires what the error was
3) GUI cross references error message in the list of possible messages
4) GUI uses the index from the cross reference to look up color in its 
own table

Dan