Python equivialent of C programming techniques (while loops)

Question

In the C programming language, I often have done the following:

while ((c = getch()) != EOF) {
 /* do something with c */
}

In Python, I have not found anything similar, since I am not allowed to set variables inside the evaluated expression. I usually end up with having to setup the evaluated expression twice!

c = sys.stdin.read(1)
while not (c == EOF):
 # Do something with c
 c = sys.stdin.read(1)

In my attempts to find a better way, I've found a way that only require to setup and the evaluated expression once, but this is getting uglier...

while True:
 c = sys.stdin.read(1)
 if (c == EOF): break
 # do stuff with c

So far I've settled with the following method for some of my cases, but this is far from optimal for the regular while loops...:

class ConditionalFileObjectReader:
 def __init__(self,fobj, filterfunc):
  self.filterfunc = filterfunc
  self.fobj = fobj
 def __iter__(self):
  return self
 def next(self):
  c = self.fobj.read(1)
  if self.filterfunc(c): raise StopIteration
  return c

for c in ConditionalFileObjectReader(sys.stdin,lambda c: c == EOF):
 print c

All my solutions to solve a simple basic programming problem has become too complex... Do anyone have a suggestion how to do this the proper way?

Answer 1

You would usually use a for loop in Python:

for c in sys.stdin.read():
    # whatever

If you don't want to buffer the whole stdin in memory at once, you can also add some buffering with a smaller buffer yourself.

Note that the constant EOF does not exist in Python. read() will simply return an empty string if no data is left in the stream.