Add ascii demo infra; add demo-ping.gif to README.md

.gitignore

@@ -1,2 +1,3 @@
 /target
 /result
+/demos/*.cast

README.md

@@ -12,7 +12,9 @@ part of a pipe. When calling a program, it can decorate stdout and
 stderr differently.
 
 stdecor is specially useful when running multiple jobs in the same
-shell.
+shell. It can be used to build scripts like the following:
+
+![demo-ping](demos/demo-ping.gif)
 
 
 ## Installation

demos/build-all.sh

@@ -0,0 +1,18 @@
+#!/bin/bash
+
+# agg=agg
+agg=(docker run --rm -it -u "$(id -u):$(id -g)" -v "$PWD:/data" lpenz/agg:1.4.3)
+
+set -e -x
+
+for demofile in ./demos/*.py; do
+    name="${demofile##*/}"
+    name="${name//.py/}"
+    asciinema rec --overwrite \
+        --rows 25 --cols 100 \
+        -c "$demofile" "demos/${name}.cast"
+    "${agg[@]}" \
+        --speed 1 \
+        --theme asciinema \
+        "demos/${name}.cast" "demos/${name}.gif"
+done

demos/demo-ping.py

@@ -0,0 +1,83 @@
+#!/usr/bin/env python3
+"""Generate stdecor ping demo using pexpect"""
+
+import argparse
+import os
+import sys
+import time
+
+import pexpect
+
+
+class Session(pexpect.spawn):
+    def __init__(self):
+        env = dict(os.environ)
+        env.update({"PS1": "\\$ ", "PS2": ""})
+        pexpect.spawn.__init__(
+            self,
+            "bash",
+            ["--norc"],
+            encoding="utf-8",
+            timeout=10,
+            echo=False,
+            logfile=sys.stdout,
+            env=env,
+        )
+        self._prompt = "[#$] $"
+        self.exp_prompt()
+
+    def exp_prompt(self):
+        self.expect(self._prompt)
+
+    def send(self, string, slow=None):
+        if slow:
+            prev = self.delaybeforesend
+            self.delaybeforesend = slow
+            for char in string:
+                if char == "\r":
+                    time.sleep(slow * 5)
+                pexpect.spawn.send(self, char)
+            self.delaybeforesend = prev
+        else:
+            pexpect.spawn.send(self, string)
+
+    def send_cmd(self, cmd, slow=None):
+        self.send(cmd, slow=slow)
+        if slow:
+            time.sleep(slow * 5)
+        self.send("\r")
+        self.exp_prompt()
+
+    def done(self):
+        self.send("exit\r")
+        self.expect(pexpect.EOF)
+        self.wait()
+
+
+def do_main():
+    p = Session()
+    p.delaybeforesend = 0.01
+    for line in [
+        "cat <<END > test.sh",
+        "set -x",
+        "stdecor -p '[google]' -- ping -nc8 www.google.com &",
+        "stdecor -p '[amazon]' -- ping -nc8 www.amazon.com &",
+        "wait",
+        "END",
+    ]:
+        p.send(line + "\r", slow=0.02)
+        p.expect("\n")
+    p.exp_prompt()
+    p.send_cmd("bash test.sh", slow=0.2)
+    p.send_cmd("rm -f test.sh")
+    p.done()
+
+
+def main():
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.parse_args()
+    do_main()
+
+
+if __name__ == "__main__":
+    main()