Re: Coloring error and warning messages in the gui console

[Torsten]

On 09.05.2017 22:01, Daniel J Sebald wrote:
> 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

Dan, thank you for the reply. Just to clarify, the selection of the
color is done by the GUI depending on the user's settings. The core is
just interspersing esc-sequences for the GUI's terminal emulation into
the output stream depending on warning or error. This might later be
used for the cli-version, too, if the terminal emulation is known.

When I understand your approach correctly, the core would have to wait
during the four steps of the GUI before actually printing the message?
Wouldn't this have much more impact on the core? Or should the GUI
buffer the stream and search later for the appropriate positions for
changing color before printing?

Torsten