[Rd] buggy ANSI escape sequences in R prompt

[Hugo Raguet]

Thanks for the hint. I agree with your analysis, but that still would not
explain why the continuation overrides the begining of the same line
instead of going to the next line.
I think I'll go for the two-lines prompt. If you have a Stack Overflow
account, you can post your answer and I will accept it in a couple of days.
That would also make some ad for your dynamic R prompt! It's really cool,
but overkill for my use.

Hugo

2017-02-07 14:44 GMT+01:00 Gábor Csárdi <csardi.gabor at gmail.com>:

> I guess that R does not know about ANSI sequences, and it calculates the
> width of the prompt including the characters in the sequences. You cannot
> do much about this, except maybe use a prompt that has two lines. You can
> put the colored text and whatever you like in the first line, and the
> second line can be non-ANSI.
>
> Note that this works in the terminal, but does not work in RStudio.
> RStudio does not support multi-line prompt currently.
>
> Maybe this is also interesting for you, if you want a dynamic R prompt:
> https://github.com/gaborcsardi/prompt#readme (Self-ad, sorry.)
>
> Gabor
>
> On Tue, Feb 7, 2017 at 8:59 AM, Hugo Raguet <hugo.raguet at centraliens.net>
> wrote:
>
>> When R is run interactively in a terminal which supports colors, it is
>> possible to use ANSI escape sequences in order to put colors in the
>> prompt,
>> such as
>>
>> options(prompt = "\033[0;31mThis is red\033[0m> ")
>>
>> Unfortunately, something goes wrong because for long command lines, the
>> line continuation override the prompt instead of being written in the next
>> line. The problem gets worse when using several colors, because somehow
>> each escape sequence "takes up some space" in the command line, *up to the
>> point that the end of the prompt might overwrite the beginning*. On my
>> configuration this happens with for instance
>>
>> options(prompt = paste("\033[0;31m With \033[0;32m multiple",
>>                    "\033[0;33m colors \033[0;34m this",
>>                    "\033[0;35m gets \033[0;36m really",
>>                    "\033[0;37m wrong! \033[0m"))
>>
>> Why is it so? Is there a workaround?
>>
>> PS: This rather old post seems related
>>
>> http://r.789695.n4.nabble.com/Xterm-escape-sequences-in-Prom
>> pt-td906375.html
>>
>> PPS: I posted this question on [R] section of stack overflow
>>
>> http://stackoverflow.com/questions/42072092/buggy-ansi-escap
>> e-sequences-in-r-prompt
>>
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>>
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>
>

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