Add ftp downloader example

doc/examples.rst

@@ -80,6 +80,7 @@ Additional Examples
 * :download:`context manager <../examples/context_manager.py>` - Managers and counters as context managers
 * :download:`floats <../examples/floats.py>` - Support totals and counts that are :py:class:`floats<float>`
 * :download:`multiple with logging <../examples/multiple_logging.py>` - Nested progress bars and logging
+* :download:`FTP downloader <../examples/ftp_downloader.py>` - Show progress downloading files from FTP
 
 Customization
 -------------

examples/ftp_downloader.py

@@ -0,0 +1,82 @@
+# Copyright 2018 Avram Lubkin, All Rights Reserved
+
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+"""
+Example FTP downloader
+"""
+
+import ftplib
+import os
+
+import enlighten
+
+
+SITE = 'test.rebex.net'
+USER = 'demo'
+PASSWD = 'password'
+DIR = 'pub/example'
+DEST = '/tmp'
+DEBUG = 0  # 0, 1, 2 are valid
+MANAGER = enlighten.get_manager()
+
+
+class Writer(object):
+    """
+    Context manager for handling download writes
+    """
+
+    def __init__(self, filename, size, directory=None):
+        self.filename = filename
+        self.size = size
+        if directory:
+            self.dest = os.path.join(directory, filename)
+        else:
+            self.dest = filename
+        self.status = self.fileobj = None
+
+    def __enter__(self):
+        self.status = MANAGER.counter(total=self.size, desc=self.filename,
+                                      unit='bytes', leave=False)
+        self.fileobj = open(self.dest, 'wb')
+        return self
+
+    def __exit__(self, *args):
+        self.fileobj.close()
+        self.status.close()
+
+    def write(self, block):
+        """
+        Write to local file and update progress bar
+        """
+        self.fileobj.write(block)
+        self.status.update(len(block))
+
+
+def download():
+    """
+    Download all files from an FTP share
+    """
+
+    ftp = ftplib.FTP(SITE)
+    ftp.set_debuglevel(DEBUG)
+    ftp.login(USER, PASSWD)
+    ftp.cwd(DIR)
+    filelist = ftp.nlst()
+    filecounter = MANAGER.counter(total=len(filelist), desc='Downloading',
+                                  unit='files')
+
+    for filename in filelist:
+
+        with Writer(filename, ftp.size(filename), DEST) as writer:
+            ftp.retrbinary('RETR %s' % filename, writer.write)
+        print(filename)
+        filecounter.update()
+
+    ftp.close()
+
+
+if __name__ == '__main__':
+    download()