From: Wayne Davison <wayned@users.sourceforge.net>
To: Peter Stephenson <pws@csr.com>
Cc: Zsh hackers list <zsh-workers@sunsite.dk>
Subject: Re: PATCH: PROMPT_SP
Date: Mon, 18 Jul 2005 11:13:30 -0700 [thread overview]
Message-ID: <20050718181330.GA19066@blorf.net> (raw)
In-Reply-To: <200507181032.j6IAWB4q022520@news01.csr.com>
On Mon, Jul 18, 2005 at 11:32:11AM +0100, Peter Stephenson wrote:
> Here's an update to the FAQ entry.
Good idea. I think it might be better to do a bigger rewrite, though,
so that we indicate early on that this FAQ entry's problem is largely
solved by PROMPT_SP.
What do you think of the following? (Hopefully my improved precmd
function is not too complex.)
--- Etc/FAQ.yo 18 Jul 2005 14:54:11 -0000 1.20
+++ Etc/FAQ.yo 18 Jul 2005 18:03:36 -0000
@@ -1640,43 +1640,49 @@
sect(How do I prevent the prompt overwriting output when there is no newline?)
- The problem is, for example,
+ The problem is normally limited to zsh versions prior to 4.3.0 due to the
+ advent of the PROMPT_SP option (which is enabled by default, and eliminates
+ this problem for most terminals). An example of the overwriting is:
verb(
% echo -n foo
%
)
- and the tt(foo) has been overwritten by the prompt tt(%). The reason this
- happens is that the option tt(PROMPT_CR) is enabled by default, and it
- outputs a carriage return before the prompt in order to ensure that the
- line editor knows what column it is in (this is needed to position the
- right-side prompt correctly (mytt($RPROMPT), mytt($RPS1)) and to avoid screen
- corruption when performing line editing). If you add tt(unsetopt promptcr)
- to your tt(.zshrc), you will see any partial output, but your screen may
- look weird until you press return or refresh the screen.
-
- Another solution for many terminals is to define a precmd function that
- outputs a screen-width of spaces, like this:
- verb(
- function precmd {
- echo -n ${(l:$COLUMNS:::):-}
- }
- )
- (Explanation: an empty parameter expansion is padded out to the number of
- columns on the screen.) That precmd function will only bump the screen
- down to a new line if there was output on the prompt line, otherwise the
- extra spaces get removed by the tt(PROMPT_CR) action. Although this
- typically looks fine it may result in the preceding spaces being included
- when you select a line of text with the mouse.
+ This shows a case where the word tt(foo) was output without a newline, and
+ then overwritten by the prompt line tt(%). The reason this happens is that
+ the option tt(PROMPT_CR) is enabled by default, and it outputs a carriage
+ return before the prompt in order to ensure that the line editor knows what
+ column it is in (this is needed to position the right-side prompt correctly
+ (mytt($RPROMPT), mytt($RPS1)) and to avoid screen corruption when performing
+ line editing). If you add tt(unsetopt promptcr) to your tt(.zshrc), you
+ will see any partial output, but your screen may look weird until you press
+ return or refresh the screen.
+
+ A better solution than disabling PROMPT_CR (for most terminals) is adding
+ a simpler version of the PROMPT_SP functionality to an older zsh using a
+ custom precmd function, like this one:
+ verb(
+ # Skip defining precmd if the PROMPT_SP option is available.
+ if ! eval '[[ -o promptsp ]] 2>/dev/null'; then
+ function precmd {
+ # An efficient version using termcap multi-right:
+ echo -n ' ' # Output 1 space
+ echotc RI $((COLUMNS - 3))
+ echo -n ' ' # Output 2 spaces
+ # Alternately, try replacing the above 3 lines with this echo
+ # that outputs a screen-column-width of spaces:
+ #echo -n ${(l:$COLUMNS:::):-}
+ }
+ fi
+ )
+ That precmd function will only bump the screen down to a new line if there
+ was output on the prompt line, otherwise the extra spaces get removed by
+ the tt(PROMPT_CR) action. Although this typically looks fine it may result
+ in the preceding spaces being included when you select a line of text with
+ the mouse.
One final alternative is to put a newline in your prompt -- see question
link(3.13)(313) for that.
- Version 3.0 of zsh includes a workaround: if the tt(PROMPT_SP) option
- is set, as it is by default, the shell will try to move the cursor to the
- start of the next screen line. This requires some support from the
- terminal which is available in most recent terminal emulators.
-
-
sect(What's wrong with cut and paste on my xterm?)
On the majority of modern UNIX systems, cutting text from one window and
..wayne..
next prev parent reply other threads:[~2005-07-18 18:13 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-07-14 18:25 Wayne Davison
2005-07-15 17:55 ` Wayne Davison
2005-07-16 16:06 ` Bart Schaefer
2005-07-16 19:56 ` Wayne Davison
2005-07-18 10:32 ` Peter Stephenson
2005-07-18 18:13 ` Wayne Davison [this message]
2005-07-23 13:55 ` Bart Schaefer
2005-07-23 16:53 ` Wayne Davison
2005-07-23 17:19 ` Wayne Davison
2005-07-24 5:27 ` Bart Schaefer
2005-07-24 6:10 ` Wayne Davison
2005-07-24 9:49 ` Bart Schaefer
2005-07-26 21:53 ` Wayne Davison
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