Python: Lines

One way to measure the complexity of a program is to count its number of lines of codeLinks to an external site. $($LOC$),$ excluding blank lines and comments. For instance, a program like

# Say hello

name $=$ input$("$What$\text{'}$s your name? $")$

print$($f$"$hello$,\{$name$\}")$

has just two lines of code, not four, since its first line is a comment, and its second line is blank $($i$.$e$.,$ just whitespace$).$ That$$s not that many, so odds are the program isn$$t that complex. Of course, just because a program $($or even function$)$ has more lines of code than another doesn$$t necessarily mean it$$s more complex. For instance, a function like

def is$\_$even$($n$)$:

if n $\%2==0$:

return True

else:

return False

isn$$t really twice as complex as a function like

def is$\_$even$($n$)$:

return n $\%2==0$

even though the former has $($more than$)$ twice as many lines of code. In fact, the former might arguably be simpler if it$$s easier to read! So lines of code should be taken with a grain of saltLinks to an external site..

Even so$,$ implement a program that counts the lines of a file, and outputs the number of lines of code in that file, excluding comments and blank lines. If the user does not specify exactly one command$-$line argument, or if the specified file$$s name does not end in $.$py$,$ or if the specified file does not exist, the program should instead exit via sys$.$exit.

Assume that any line that starts with #$,$ optionally preceded by whitespace, is a comment. $($A docstringLinks to an external site. should not be considered a comment.$)$ Assume that any line that only contains whitespace is blank.

Additionally, your program must include:

comments with your name, date, program name, and program purpose.

a main function with if $\_\_$name$\_\_==\text{'}\_\_$main$\_\_\text{'}$: code. See this tutorial from module $5.$

Hints

How to Test

Here$$s how to test your code manually:

Run your program with python LastNameFirstInitial$\_$Lines.py$.$ Your program should exit with sys$.$exit and provide an error message:

Too few command$-$line arguments

Create two python programs, hello.py and goodbye.py$.$ Run python LastNameFirstInitial$\_$Lines.py hello.py goodbye.py$.$ Your program should exit with sys$.$exit and provide an error message:

Too many command$-$line arguments

Create a text file called invalid$\_$extension.txt$.$ Run your program with python LastNameFirstInitial$\_$Lines.py invalid$\_$extension.txt$.$ Your program should exit with sys$.$exit and provide an error message:

Not a Python file

Run your program with python LastNameFirstInitial$\_$Lines.py non$\_$existent$\_$file.py$.$ Assuming non$\_$existent$\_$file.py doesn$$t exist, your program should exit with sys$.$exit and provide an error message:

File does not exist

Create additional python programs which vary in complexity: create some with comments, some docstrings, and some whitespace. For each of these files run python LastNameFirstInitial$\_$Lines.py FILENAME where FILENAME is the name of the file. Lines.py should output the number of lines, excluding comments and whitespace, present in the given file.