Question

I’m attempting to use Map to reference a class function, but am having difficulty with formatting/ordering. I have heard that using map is sort of obsolete so I am definitely open to alternative solutions (for loops?) Thanks in advance.

lognames =  [ "C:\Users\makker1\Desktop\logs\loga.txt",
              "C:\Users\makker1\Desktop\logs\logb.txt",
              "C:\Users\makker1\Desktop\logs\logc.txt" ]

class LogFile:
    def __init__(self,filepath):
        self.logfile = open(filepath, "r")
        self.head = None

    def __str__(self):
        return "x=" + str(self.x) + "y="+str(self.y)

    def readline (self):
        if self.head != None:
            self.head = self.logfile.readline()

    def previewline (self):
        if self.head == None:
            self.head = self.logfile.readline()

    def close (self):
        self.logfile.close()



logs = map(LogFile(self,filepath).__init__(), lognames)
heads = map(lambda log: None, logs)


>>> 
Traceback (most recent call last):
  File "C:\Users\makker1\Desktop\mergesort-final.py", line 30, in <module>
    logs = map(LogFile(self,filepath).__init__, lognames)
NameError: name 'self' is not defined
>>> 

If any more info is needed, please let me know. I realize that there are tons of posts about this very problem and have sorted through many of them with no avail.

Answer 1

You don’t have to call __init__ explicitly. Try:

logs = map(LogFile, lognames)

Sometimes it helps to think of a class as being callable. You can think of a class as something like the following:

def LogFile(filepath):
    class _LogFile:
        def __init__(self, path):
            ...
    return _LogFile(filepath)

Basically, a class can be thought of as something that you call to create an object instance. This isn’t really true, but in many cases it will appear to be.