Update Ch 17 exercise solutions

somacdivad · somacdivad · commit 302450667168 · 2019-11-14T11:57:31.000-06:00
diff --git a/ch17-graphical-user-interfaces/1-add-gui-elements-with-easygui.py b/ch17-graphical-user-interfaces/1-add-gui-elements-with-easygui.py
@@ -0,0 +1,12 @@
+# 17.1 - Add GUI Elements with EasyGUI
+# Review Exercises
+
+import easygui as gui
+
+
+# Exercise #1
+gui.msgbox(msg="Warning!", title="Watch out!", ok_button="I'll be careful")
+
+
+# Exercise #2
+gui.enterbox(msg="What is your name?")
diff --git a/ch17-graphical-user-interfaces/10-challenge-return-of-the-poet.py b/ch17-graphical-user-interfaces/10-challenge-return-of-the-poet.py
@@ -1,4 +1,4 @@
-# 17.6 - Challenge: Return of the Poet
+# 17.10 - Challenge: Return of the Poet
 # Solution to challenge
 
 # Please note that there are many ways to solve this challenge. The code
diff --git a/ch17-graphical-user-interfaces/2-example-app-pdf-page-rotator.py b/ch17-graphical-user-interfaces/2-example-app-pdf-page-rotator.py
@@ -1,9 +1,5 @@
-# 17.1 - Add GUI Elements With EasyGUI
-# Review Exercise #4
-
-# NOTE: The first three exercises in this section are instructional
-# and do not require solutions to be shown here. For this reason,
-# only the solution to the fourth exercise is presented.
+# 17.2 - Example App: PDF Page Rotator
+# Review Exercise #1
 
 import easygui as gui
 from PyPDF2 import PdfFileReader, PdfFileWriter
diff --git a/ch17-graphical-user-interfaces/3-challenge-use-gui-elements-to-help-a-user-modify-files.py b/ch17-graphical-user-interfaces/3-challenge-use-gui-elements-to-help-a-user-modify-files.py
@@ -1,30 +1,33 @@
-# 17.2 - Challenge: Use GUI Elements to Help a User Modify Files
+# 17.3 - Challenge: Use GUI Elements to Help a User Modify Files
 # Solution to challenge
 
 # save part of a PDF based on a user-supplied page range using a GUI
 
 import easygui as gui
 from PyPDF2 import PdfFileReader, PdfFileWriter
 
-# let the user choose an input file
+# 1. Ask the user to select a PDF file to open.
 input_file_path = gui.fileopenbox("", "Select a PDF to trim...", "*.pdf")
-if input_file_path is None:  # exit on "Cancel"
-    exit()
 
-# get the page length of the input file
-input_file = PdfFileReader(input_file_path)
-total_pages = input_file.getNumPages()
+# 2. If no PDF file is chosen, exit the program.
+if input_file_path is None:
+    exit()
 
-# let the user choose a beginning page
+# 3. Ask for a starting page number.
 page_start = gui.enterbox(
     "Enter the number of the first page to use:", "Where to begin?"
 )
-if page_start is None:  # exit on "Cancel"
+
+# 4. If the user does not enter a starting page number, exit the program.
+if page_start is None:
     exit()
-# check for possible problems and try again:
-#    1) input page number isn't a (non-negative) digit
-# or 2) input page number is 0
-# or 3) page number is greater than total number of pages
+
+# 5. Valid page numbers are positive integers. If the user enters an invalid page number:
+#     - Warn the user that the entry is invalid
+#     - Return to step 3.
+# This solution also checks that the starting page number is not beyond the last page of the PDF!# 3. Asl for a starting page number.
+input_file = PdfFileReader(input_file_path)  # Open the PDF
+total_pages = input_file.getNumPages()  # Get the total number of pages
 while (
     not page_start.isdigit()
     or page_start == "0"
@@ -37,17 +40,20 @@
     if page_start is None:  # exit on "Cancel"
         exit()
 
-# let the user choose an ending page
+# 6. Ask for an ending page number
 page_end = gui.enterbox(
     "Enter the number of the last page to use:", "Where to end?"
 )
+
+# 7. If the user does not enter and ending page number, exit the program.
 if page_end is None:  # exit on "Cancel"
     exit()
-# check for possible problems and try again:
-#    1) input page number isn't a (non-negative) digit
-# or 2) input page number is 0
-# or 3) input page number is greater than total number of pages
-# or 4) input page number for end is less than page number for beginning
+
+# 8. If the user enters an invalid page number:
+#     - Warn the user that the entry is invalid
+#     - Return to step 6.
+# This solution also check that the ending page number is not less than the starting
+# page number, and that it is not greater than the last page in the PDF
 while (
     not page_end.isdigit()
     or page_end == "0"
@@ -61,21 +67,29 @@
     if page_end is None:  # exit on "Cancel"
         exit()
 
-# let the user choose an output file name
+# 9. Ask for the location to save the extracted pages
 output_file_path = gui.filesavebox("", "Save the trimmed PDF as...", "*.pdf")
+
+# 10. If the user does not select a save location, exit the program.
+if output_file_path is None:
+    exit()
+
+# 11. If the chosen save location is the same as the input file path:
+#      - Warn the user that they can not overwrite the input file.
+#      - Return the step 9.
 while input_file_path == output_file_path:  # cannot use same file as input
     gui.msgbox(
         "Cannot overwrite original file!", "Please choose another file..."
     )
     output_file_path = gui.filesavebox(
         "", "Save the trimmed PDF as...", "*.pdf"
     )
-if output_file_path is None:
-    exit()  # exit on "Cancel"
+    if output_file_path is None:
+        exit()
 
-# read in file, write new file with trimmed page range and save the new file
+# 12. Perform the page extraction
 output_PDF = PdfFileWriter()
-# subtract 1 from supplied start page number to get correct index value
+
 for page_num in range(int(page_start) - 1, int(page_end)):
     page = input_file.getPage(page_num)
     output_PDF.addPage(page)
diff --git a/ch17-graphical-user-interfaces/4-control-layout-with-geometry-managers.py b/ch17-graphical-user-interfaces/4-control-layout-with-geometry-managers.py
diff --git a/ch17-graphical-user-interfaces/4-introduction-to-tkinter.py b/ch17-graphical-user-interfaces/4-introduction-to-tkinter.py
@@ -0,0 +1,24 @@
+# 17.4 - Introduction to Tkinter
+# Review exercises
+
+import tkinter as tk
+
+# Exercise 1
+window = tk.Tk()
+label = tk.Label(text="GUIs are great!")
+label.pack()
+window.mainloop()
+
+
+# Exercise 2
+window = tk.Tk()
+label = tk.Label(text="Python rocks!")
+label.pack()
+window.mainloop()
+
+
+# Exercise 3
+window = tk.Tk()
+label = tk.Label(text="Engage!")
+label.pack()
+window.mainloop()
diff --git a/ch17-graphical-user-interfaces/5-working-with-widgets.py b/ch17-graphical-user-interfaces/5-working-with-widgets.py
@@ -0,0 +1,25 @@
+# 17.4 - Introduction to Tkinter
+# Review exercises
+
+import tkinter as tk
+
+
+# Exercise 1 asks you to recreate all the windows in the chapter.
+# The source code for each window can be found in the chapter text.
+
+
+# Exercise 2
+window = tk.Tk()
+button = tk.Button(
+    width=50, height=25, bg="white", fg="blue", text="Click here"
+)
+button.pack()
+window.mainloop()
+
+
+# Exercise 3
+window = tk.Tk()
+entry = tk.Entry(width=40)
+entry.insert(0, "What is your name?")
+entry.pack()
+window.mainloop()
diff --git a/ch17-graphical-user-interfaces/6-control-layout-with-geometry-managers.py b/ch17-graphical-user-interfaces/6-control-layout-with-geometry-managers.py
diff --git a/ch17-graphical-user-interfaces/7-make-your-applications-interactive.py b/ch17-graphical-user-interfaces/7-make-your-applications-interactive.py

Original file line number	Diff line number	Diff line change
`@@ -1,4 +1,4 @@`
`1`		`-# 17.6 - Challenge: Return of the Poet`
	`1`	`+# 17.10 - Challenge: Return of the Poet`
`2`	`2`	`# Solution to challenge`
`3`	`3`
`4`	`4`	`# Please note that there are many ways to solve this challenge. The code`