From 0b53c462de7a0ec2df99e8876db8bbfa8ec5c873 Mon Sep 17 00:00:00 2001
From: Noelle Leigh <noelle@tilde.town>
Date: Mon, 2 Jun 2025 16:49:43 -0400
Subject: [PATCH] Make validate_car raise exception on failure instead of
 returning 0

---
 tilde-train.py | 29 ++++++++++++++++-------------
 1 file changed, 16 insertions(+), 13 deletions(-)

diff --git a/tilde-train.py b/tilde-train.py
index efede48..c71ff1d 100755
--- a/tilde-train.py
+++ b/tilde-train.py
@@ -90,6 +90,9 @@ default_car = [
   r"   \__/ \__/      \__/ \__/   ",
 ]
 
+class CarError(Exception):
+  """Error related validating a car."""
+
 def print_help():
   print(
     cleandoc(
@@ -206,9 +209,11 @@ def validate_car(car: list[str]):
   while car_list[(len(car_list)-1)].strip() == "":
     car_list.pop() # clear bottom
 
-  # len(choochoo_list) is the height of the train car, in number of rows.
-  if len(car_list) > max_y+1 or len(car_list) == 0:
-    return 0  # train car too tall or non-existant; skip it.
+  # len(car_list) is the height of the train car, in number of rows.
+  if len(car_list) > max_y+1:
+    raise CarError(f"Car is too tall ({len(car_list)} > {max_y + 1}).")
+  if len(car_list) == 0:
+    raise CarError(f"Car is empty.")
 
   # vertically pad short cars with 1 space (lines will be lengthened later).
   while len(car_list) < max_y:
@@ -221,9 +226,9 @@ def validate_car(car: list[str]):
 
   for idx,row in enumerate(car_list):
     if len(row) > max_x+1: # check length of each row in .choochoo file.
-      return 0 # train car too long; skip it.
+      raise CarError(f"Car is too wide ({len(row)} > {max_x + 1}).")
     elif "\t" in row or "\v" in row or "\f" in row or "\r" in row:
-      return 0 # skip if contains tabs, vert tabs, line feeds or carriage ret
+      raise CarError(f"Car contains illegal control characters.")
     elif len(row) < longest_line:
       padding = " "*(longest_line - len(row))
       car_list[idx] += padding # add padding spaces.
@@ -241,13 +246,12 @@ def print_all_cars():
         continue # the train car was too tall; skip it.
 
       car = validate_car(choochoo_list) # printing is only a DEBUG feature.
-      if car != 0:
-        print("")
-        print(fname + ":")
-        print("\n".join(car)) # print the car to stdout
+      print("")
+      print(fname + ":")
+      print("\n".join(car)) # print the car to stdout
 
     except:
-      pass;
+      pass
 
 
 def chuggachugga(stdscr: curses.window):
@@ -306,11 +310,10 @@ for fname in glob.glob('/home/*/' + traincarFN):
       continue # the train car was too tall; skip it.
 
     car = validate_car(choochoo_list) # printing is only a DEBUG feature.
-    if car != 0:
-      cars.append(car) # start a list of lists (list of cars) here.
+    cars.append(car) # start a list of lists (list of cars) here.
 
   except:
-    pass;
+    pass
 
 while len(cars) < max_cars:
   cars.append([*default_car]) # add copies of default cars if train too short