better error handling, corrected question typos

Author: learnbyexample

interactive_exercises/questions.json

@@ -247,7 +247,7 @@
             "always X",
             "a X"
         ],
-        "Reference solution": "re.sub(r'test.+', r'X', flags=re.I)"
+        "Reference solution": "re.sub(r'test.+', r'X', s, flags=re.I)"
     },
     "15": {
         "question": "Split the given input strings to get the corresponding output as shown below.",
@@ -423,7 +423,7 @@
         "right column": [
             "redo X credible :X: rod X"
         ],
-        "Reference solution": "re.sub(r'\\bre[ae]?d\\b', 'X', s)"
+        "Reference solution": "re.sub(r'\\bre[ae]?d\\b', r'X', s)"
     },
     "25": {
         "question": "Change whole words starting with `hand` and ending with `s` or `y` or `le` to `X.",
@@ -540,9 +540,15 @@
         "flags": "0",
         "function": "re.split",
         "left column": [
+            "food:good",
+            "food:good-cool",
+            "food:good-cool;tool",
             "42:no-op;10:car-tr:u-ck;SQ1"
         ],
         "right column": [
+            "['food:good']",
+            "['food:good-cool']",
+            "['food', 'cool', 'tool']",
             "['42', 'op', '10', 'tr:u-ck', 'SQ1']"
         ],
         "Reference solution": "re.split(r':[^-]+-([^;]+);', s)"
@@ -557,7 +563,7 @@
         "right column": [
             "a\n1<> b 2<>"
         ],
-        "Reference solution": "re.sub(r'<[^>]+>', s)"
+        "Reference solution": "re.sub(r'<[^>]+>', r'', s)"
     },
     "34": {
         "question": "Match strings whose first non-whitespace character is not a `#` character. Any string made up of only whitespace characters should not be matched.",
@@ -611,7 +617,7 @@
         "right column": [
             "X not X X X took X"
         ],
-        "Reference solution": "re.sub(r'\\b(\\w|(\\w)\\w*\\2)\\b', 'X', s, flags=re.I)"
+        "Reference solution": "re.sub(r'\\b(\\w|(\\w)\\w*\\2)\\b', r'X', s, flags=re.I)"
     },
     "38": {
         "question": "Convert the given markdown anchors to hyperlinks as shown below.",
@@ -729,7 +735,7 @@
             "{{cherry-200",
             "2-42"
         ],
-        "Reference solution": "re.search(r'\\A({{)?[a-z]+-\\d+(?(1)}})\\Z', w)"
+        "Reference solution": "re.search(r'\\A({{)?[a-z]+-\\d+(?(1)}})\\Z', s)"
     },
     "46": {
         "question": "Replace all whole words with `X` unless it is preceded by `(` character.",
@@ -743,7 +749,7 @@
             "(apple) X X)",
             "X (mango) (grape"
         ],
-        "Reference solution": "re.sub(r'(?<!\\()\\b\\w+', 'X', s)"
+        "Reference solution": "re.sub(r'(?<!\\()\\b\\w+', r'X', s)"
     },
     "47": {
         "question": "Replace all whole words with `X` unless it is followed by `)` character.",
@@ -757,7 +763,7 @@
             "(apple) X berry)",
             "X (mango) (X"
         ],
-        "Reference solution": "re.sub(r'\\b\\w+\\b(?!\\))', 'X', s)"
+        "Reference solution": "re.sub(r'\\b\\w+\\b(?!\\))', r'X', s)"
     },
     "48": {
         "question": "Replace all whole words with `X` unless it is preceded by `(` or followed by `)` characters.",
@@ -771,7 +777,7 @@
             "(apple) X berry)",
             "X (mango) (grape"
         ],
-        "Reference solution": "re.sub(r'(?<!\\()\\b\\w+\\b(?!\\))', 'X', s)"
+        "Reference solution": "re.sub(r'(?<!\\()\\b\\w+\\b(?!\\))', r'X', s)"
     },
     "49": {
         "question": "Extract all whole words that do not end with `e` or `n`.",
@@ -875,7 +881,7 @@
             "hello,nice   ice,42,2",
             "1,,stall   small"
         ],
-        "Reference solution": "re.sub(r'(?<![^,])\\s+|\\s+(?![^,])', s)"
+        "Reference solution": "re.sub(r'(?<![^,])\\s+|\\s+(?![^,])', r'', s)"
     },
     "56": {
         "question": "Match strings that satisfy all of these rules:\n* at least two alphabets\n* at least 3 digits\n* doesn't end with a whitespace character",
@@ -995,7 +1001,7 @@
             "But Cool Te",
             "it this ."
         ],
-        "Reference solution": "re.sub(r'hat.*it', r'', flags=re.S|re.I)"
+        "Reference solution": "re.sub(r'hat.*it', r'', s, flags=re.S|re.I)"
     },
     "64": {
         "question": "Delete from `start` if it is at the beginning of a line up to the next occurrence of the `end` at the end of a line. Match these markers case insensitively.",

interactive_exercises/regex_practice.py

@@ -1,8 +1,10 @@
 import json
+import os
 import re
 import sys
 import tkinter as tk
 from tkinter import ttk
+from tkinter.messagebox import showwarning, showerror
 
 class Root(tk.Tk):
     def __init__(self):
@@ -143,7 +145,6 @@ def create_button_frame(self):
 
     def initialize(self):
         self.format = {0: str, 1: repr}
-        self.format_change = {0: eval, 1: repr}
         self.previous_format = self.test_string_format.get()
 
         self.progress_file = 'user_progress.json'
@@ -153,27 +154,29 @@ def initialize(self):
         except FileNotFoundError:
             self.user_progress = {}
 
-        # todo: handle FileNotFoundError
         with open('questions.json') as f:
             all_questions = json.load(f)
         self.questions = tuple(v for k, v in all_questions.items())
         self.question_count = len(self.questions)
 
         self.question_idx = 0
-        try:
-            self.question_idx = int(sys.argv[1]) - 1
-        except (IndexError, ValueError):
-            # todo: find a better way
-            pass
-        else:
-            if self.question_idx < 0:
-                self.question_idx = 0
-            elif self.question_idx >= self.question_count:
-                self.question_idx = self.question_count - 1
+        if len(sys.argv) == 2:
+            try:
+                self.question_idx = int(sys.argv[1]) - 1
+            except ValueError:
+                showwarning("Warning!",
+                            ("Couldn't convert cli argument to integer!"
+                             "\n\nDefault question will be shown"))
+            else:
+                if self.question_idx < 0:
+                    self.question_idx = 0
+                elif self.question_idx >= self.question_count:
+                    self.question_idx = self.question_count - 1
 
         self.display_question(self.questions[self.question_idx])
         # skip already answered questions
-        for idx in range(self.question_count):
+        # selecting already answered question (via sys.argv[1]) is also skipped!
+        for idx in range(self.question_idx, self.question_count):
             progress_key = str(idx)
             if self.user_progress.get(progress_key, ('', '', 0, False))[3]:
                 self.next()
@@ -248,8 +251,11 @@ def change_format(self):
         new_format = self.test_string_format.get()
         if new_format != self.previous_format:
             self.previous_format = new_format
-            for label in self.l_test_strings:
-                label['text'] = self.format_change[new_format](label['text'])
+            fmt_func = self.format[new_format]
+            for row, t in enumerate(zip(self.left_col, self.right_col)):
+                idx = row * 2
+                self.l_test_strings[idx]['text'] = fmt_func(t[0])
+                self.l_test_strings[idx + 1]['text'] = fmt_func(t[1])
 
     def next(self, previous=False):
         self.save_progress()
@@ -355,7 +361,10 @@ def quit(self):
         self.destroy()
 
 if __name__ == '__main__':
-    root = Root()
-    root.protocol('WM_DELETE_WINDOW', root.quit)
-    root.mainloop()
+    if not os.path.isfile('questions.json'):
+        showerror("Error!", "questions.json not found!")
+    else:
+        root = Root()
+        root.protocol('WM_DELETE_WINDOW', root.quit)
+        root.mainloop()