types.py

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#!/usr/bin/python
# -*- coding: utf-8 -*- 
#
# This file contains conversion functions that allow the same code to be 
# used in both python 2 and python 3 with minimum modifications. 
 
import sys
import subprocess
import inspect
 
PY2 = sys.version_info[0] == 2
PY3 = sys.version_info[0] == 3
 
# =====================================================================
if PY2:
  def S(v):
    """Converts the value into a byte string.
    """
    if isinstance(v, unicode):
      return v.encode(sys.getfilesystemencoding())
      
    return str(v)
    
  def U(v):
    """Converts the value into a unicode string.
    """
    if isinstance(v, str):
      return v.decode(sys.getfilesystemencoding())
      
    return unicode(v)
    
  def Print(v, *args):
    """Print a unicode string with arguments.
    """
    print(Printf(v, *args))
    
  def PrintB(v, *args):
    """Print a byte string with arguments.
    """
    print(S(Printf(v, *args)))
    
  def Printf(v, *args):
    """Returns a formatted unicode string.
    """
    if args:
      if isinstance(args, tuple):
        args  = [U(a) for a in args]
        return U(v).format(*args)
      else:
        return U(v).format(U(args))
        
    return v
    
  def PrintL(v, localdict = None):
    """Print a string formatted with local variables.
    """
    
    if not localdict:
      localdict = inspect.currentframe().f_back.f_locals
    
    print(PrintLf(v, localdict))
    
  def PrintBL(v, localdict = None):
    """Print a byte string formatted with local variables.
    """
    
    if not localdict:
      localdict = inspect.currentframe().f_back.f_locals
    
    print(S(PrintLf(v, localdict)))
    
  def PrintLf(s, localdict  = None):
    """Returns a string formatted with local variables.
    """
    if not localdict:
      localdict = inspect.currentframe().f_back.f_locals
      
    udict = {}
    
    for k, v in localdict.iteritems():
      if isinstance(v, str):
        udict[k]  = v.decode(sys.getfilesystemencoding())
      else:
        udict[k]  = v
      
    return U(s).format(**udict)
    
# =====================================================================
elif PY3:
  def S(v):
    """Converts the value into a byte string.
    """
    if not isinstance(v, bytes):
      return bytes(v, sys.getfilesystemencoding())
      
    return v
    
  def U(v):
    """Converts the value into a unicode string.
    """
    if not isinstance(v, str):
      return str(v, sys.getfilesystemencoding())
    
    return v
    
  def Print(v, *args):
    """Prints the string with arguments.
    """
    print(Printf(v, *args))
    
  def Printf(v, *args):
    """Returns a string with converted arguments.
    """
    if args:
      if isinstance(args, tuple):
        return v.format(*args)
      else:
        return v.format(args)
        
    return v
    
  def PrintL(v, localdict = None):
    """Prints a string formatted with local variables.
    """
    if not localdict:
      localdict = inspect.currentframe().f_back.f_locals
      
    print(PrintLf(v, localdict))
    
  def PrintLf(v, localdict = None):
    """Returns a string formatted with local variables.
    """
    if not localdict:
      localdict = inspect.currentframe().f_back.f_locals
    
    return v.format(**localdict)
    
  def RunCommand(cmdlist):
    """Runs a command and returns unicode output
    """
    cmdlist = [U(t) for t in cmdlist]
    return U(subprocess.check_output(cmdlist))
    
  def RunDaemon(cmdlist):
    """Runs a command in the background
    """
    cmdlist = [U(t) for t in cmdlist]
    subprocess.Popen(cmdlist)
 
# =====================================================================
def V(d, k, default = None):
  """Utility function to get a value from a dict or object given its 
  name. Will return default if it can't be found.
 
  The V functions are convenience functions designed to ensure that 
  a value is the correct type before being used for any work. 
  """
  try:
    return d[k]
  except:
    try:
      return getattr(d, k)
    except:
      pass
 
  return default
 
# =====================================================================
def IntV(d, k, min = None, max = None, default = 0):
  """Utility function to get an int from a dict or object given its 
  name. Will return default if it can't be found.
 
  The V functions are convenience functions designed to ensure that 
  a value is the correct type before being used for any work. 
  """
  v = default
 
  try:
    v = int(d[k])
  except:
    try:
      v = int(getattr(d, k))
    except:
      return default
 
  if min is not None and v < min:
    v = min
 
  if max is not None and v > max:
    v = max
    
  return v
 
# =====================================================================
def FloatV(d, k, min = None, max = None, default = 0.0):
  """Utility function to get a float from a dict or object given its 
  name. Will return default if it can't be found.
 
  The V functions are convenience functions designed to ensure that 
  a value is the correct type before being used for any work. 
  """
  v = default
 
  try:
    v = float(d[k])
  except:
    try:
      v = float(getattr(d, k))
    except:
      return default
 
  if min is not None and v < min:
    v = min
 
  if max is not None and v > max:
    v = max
    
  return v
 
# =====================================================================
def StrV(d, k, default = ''):
  """Utility function to get a string from a dict or object given its 
  name. Will return default if it can't be found.
 
  The V functions are convenience functions designed to ensure that 
  a value is the correct type before being used for any work. 
  """
  v = default
 
  try:
    v = str(d[k])
  except:
    try:
      v = str(getattr(d, k))
    except:
      return default
 
  return v
 
# =====================================================================
def ArrayV(d, k, default = []):
  """Utility function to get an array from a dict or object given its 
  name. Will return default if it can't be found.
 
  The V functions are convenience functions designed to ensure that 
  a value is the correct type before being used for any work. 
  """
  v = default
 
  try:
    v = d[k]
  except:
    try:
      v = getattr(d, k)
    except:
      return default
 
  if not isinstance(v, list) and not isinstance(v, tuple):
    v = []
    
  return v
 
# =====================================================================
def DictV(d, k, default = {}):
  """Utility function to get a dict from a dict or object given its 
  name. Will return default if it can't be found.
 
  The V functions are convenience functions designed to ensure that 
  a value is the correct type before being used for any work. 
  """
  v = default
 
  try:
    v = d[k]
  except:
    try:
      v = getattr(d, k)
    except:
      return default
 
  if not isinstance(v, dict):
    v = {}
    
  return v