Question

I’m trying to use the str.find() and it keeps raising an error, what am I doing wrong?

import codecs

    def countLOC(inFile):
        """ Receives a file and then returns the amount
            of actual lines of code by not counting commented
            or blank lines """

        LOC = 0  
        for line in inFile:
            if line.isspace():
                continue
            comment = line.find('#')
            if comment > 0:
                for letter in range(comment):
                    if not letter.whitespace:
                        LOC += 1
                        break            
        return LOC

    if __name__ == "__main__":
        while True:
            file_loc = input("Enter the file name: ").strip()
            try:
                source = codecs.open(file_loc)
            except:
                print ("**Invalid filename**")
            else:
                break 
        LOC_count = countLOC(source)

        print ("\nThere were {0} lines of code in {1}".format(LOC_count,source.name))

Error

  File "C:\Users\Justen-san\Documents\Eclipse Workspace\countLOC\src\root\nested\linesOfCode.py", line 12, in countLOC
        comment = line.find('#')
    TypeError: expected an object with the buffer interface

Answer 1

Use the built-in function open() instead of codecs.open().

You’re running afoul of the difference between non-Unicode (Python 3 bytes, Python 2 str) and Unicode (Python 3 str, Python 2 unicode) string types. Python 3 won’t convert automatically between non-Unicode and Unicode like Python 2 will. Using codecs.open() without an encoding parameter returns an object which yields bytes when you read from it.

Also, your countLOC function won’t work:

for letter in range(comment):
    if not letter.whitespace:
        LOC += 1
        break            

That for loop will iterate over the numbers from zero to one less than the position of '#' in the string (letter = 0, 1, 2...); whitespace isn’t a method of integers, and even if it were, you’re not calling it.

Also, you’re never incrementing LOC if the line doesn’t contain #.

A “fixed” but otherwise faithful (and inefficient) version of your countLOC:

def countLOC(inFile):
    LOC = 0  
    for line in inFile:
        if line.isspace():
            continue
        comment = line.find('#')
        if comment > 0:
            for letter in line[:comment]:
                if not letter.isspace():
                    LOC += 1
                    break
        else:
            LOC += 1
    return LOC

How I might write the function:

def count_LOC(in_file):
    loc = 0  
    for line in in_file:
        line = line.lstrip()
        if len(line) > 0 and not line.startswith('#'):
            loc += 1
    return loc