Debug-time environment variables can be set with set_env.py

1 files changed, 95 insertions, 0 deletions

diff --git a/lab/set_env.py b/lab/set_env.py
new file mode 100755
index 00000000..184649ee
--- /dev/null
+++ b/lab/set_env.py
@@ -0,0 +1,95 @@
+#!/usr/bin/env python3
+#
+# Run this like:
+#
+#   $ $(lab/set_env.py)
+#
+
+import functools
+import glob
+import itertools
+import os
+import re
+import sys
+
+pstderr = functools.partial(print, file=sys.stderr)
+
+SETTINGS = []
+
+line_pattern = r"\$set_env.py: (\w+) - (.*)"
+globs = "*/*.py *.py"
+
+filenames = itertools.chain.from_iterable(glob.glob(g) for g in globs.split())
+files = 0
+for filename in filenames:
+    files += 1
+    with open(filename) as f:
+        for line in f:
+            m = re.search(line_pattern, line)
+            if m:
+                SETTINGS.append(m.groups())
+pstderr("Read {} files".format(files))
+
+
+def read_them():
+    values = {}
+    for name, _ in SETTINGS:
+        values[name] = os.environ.get(name)
+    return values
+
+def show_them(values):
+    for i, (name, description) in enumerate(SETTINGS, start=1):
+        value = values[name]
+        if value is None:
+            eq = ' '
+            value = ''
+        else:
+            eq = '='
+            value = repr(value)
+        pstderr("{:2d}: {:>30s} {} {:12s}   {}".format(i, name, eq, value, description))
+
+def set_by_num(values, n, value):
+    setting_name = SETTINGS[int(n)-1][0]
+    values[setting_name] = value
+
+def get_new_values(values):
+    show = True
+    while True:
+        if show:
+            show_them(values)
+            show = False
+            pstderr("")
+        pstderr("> ", end='')
+        sys.stderr.flush()
+        try:
+            cmd = input("").strip().split(None, 1)
+        except EOFError:
+            pstderr("\n")
+            break
+        if not cmd:
+            continue
+        if cmd[0] == 'q':
+            break
+        if cmd[0] == 'x':
+            set_by_num(values, cmd[1], None)
+        else:
+            try:
+                nsetting = int(cmd[0])
+            except ValueError:
+                pass
+            else:
+                set_by_num(values, nsetting, cmd[1])
+        show = True
+
+    return values
+
+def as_exports(values):
+    exports = []
+    for name, value in values.items():
+        if value is None:
+            exports.append("export -n {}".format(name))
+        else:
+            exports.append("export {}={!r}".format(name, value))
+    return "eval " + "; ".join(exports)
+
+print(as_exports(get_new_values(read_them())))