Mailing-List: contact zsh-workers-help@zsh.org; run by ezmlm
Precedence: bulk
From: Bart Schaefer <schaefer@brasslantern.com>
Message-Id: <160114185941.ZM18307@torch.brasslantern.com>
Date: Thu, 14 Jan 2016 18:59:41 -0800
In-Reply-To: <20160114171631.GC12351@cventin.lip.ens-lyon.fr>
Comments: In reply to Vincent Lefevre <vincent@vinc17.net>
        "prompt update and TRAPCHLD" (Jan 14,  6:16pm)
References: <20160114171631.GC12351@cventin.lip.ens-lyon.fr>
To: zsh-workers@zsh.org
Subject: Re: prompt update and TRAPCHLD
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii

On Jan 14,  6:16pm, Vincent Lefevre wrote:
} Subject: prompt update and TRAPCHLD
}
} There seems to be a bug in the prompt update. The change of psvar[1]
} in TRAPCHLD is not taken into account for the next prompt display,
} but for the following one.

That's because the prompt is being redrawn before TRAPCHILD executes.
If you change it to:

TRAPCHLD() { psvar[1]=$RANDOM; print "set $psvar[1]" }

You can see where the print output appears relative to the prompt:

18:50:09-% sleep 7 & sleep 5 & sleep 9 &
[1] 18276
[2] 18277
[3] 18278
18:50:11-% 
[2]  - done       sleep 5
18:50:16-% set 23539

[1]  - done       sleep 7
18:50:18-23539% set 5119

[3]  + done       sleep 9
18:50:20-5119% set 17622

The right thing is to explicitly tell ZLE to update the prompt:

TRAPCHLD() {
  psvar[1]=$RANDOM
  [[ -o zle ]] && zle reset-prompt
}  

Or perhaps your complaint is that the TRAP* function should run sooner?