FileHelper

 

 

# -*- coding: utf-8 -*-
#@File name    : filehelper.py
#@Auther    : jianglb-alibaba
#@date        : 2017-03-19
import collections

def isfilelike_r(f):
    """
    Check if object 'f' is readable file-like 
    that it has callable attributes 'read' and 'close'
    """
    try:
        if isinstance(getattr(f, "read"), collections.Callable) \
            and isinstance(getattr(f, "close"), collections.Callable):
            return True
    except AttributeError:
        pass
    return False

def isfilelike_w(f):
    """
    Check if object 'f' is readable file-like 
    that it has callable attributes 'write' and 'close'
    """
    try:
        if isinstance(getattr(f, "write"), collections.Callable) \
            and isinstance(getattr(f, "close"), collections.Callable):
            return True
    except AttributeError:
        pass
    return False

def isfilelike(f):
    """
    Check if object 'f' is readable file-like 
    that it has callable attributes 'read' , 'write' and 'closer'
    """
    try:
        if isinstance(getattr(f, "read"), collections.Callable) \
            and isinstance(getattr(f, "write"), collections.Callable) \
                and isinstance(getattr(f, "close"), collections.Callable):
            return True
    except AttributeError:
        pass
    return False

def fileinoutpattern(inp, out, callback=None, inmode="r", outmode="wb"):
    """
    Make sure that 'inp' and 'out' has been 'converted' to file objects, 
    and call 'callback' with them, finally clear it up. 
    """
    # Set up
    fin = inp
    if not isfilelike_r(fin):
        fin = open(inp, inmode)
    fout = out
    if not isfilelike_w(fout):
        fout = open(out, outmode)
    
    # Call the 'callback'
    result = None
    if callback != None:
        result = callback(fin, fout)

    # Clear up
    if not isfilelike_r(inp):
        fin.close()
    if not isfilelike_w(out):
        fout.close()
    
    return result