From 6dbda8b2f60a1d8dcfdd7f4443a110ac519dbcad Mon Sep 17 00:00:00 2001
From: Will McGugan <willmcgugan@gmail.com>
Date: Thu, 28 Dec 2017 13:44:23 +0000
Subject: [PATCH] added extract method

---
 fs/base.py          | 28 +++++++++++++++++++++++++++-
 fs/test.py          | 10 ++++++++++
 tests/test_ftpfs.py |  1 -
 3 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/fs/base.py b/fs/base.py
index 4672161d..a051428c 100644
--- a/fs/base.py
+++ b/fs/base.py
@@ -43,7 +43,7 @@ class FS(object):
 
     # This is the "standard" meta namespace.
     _meta = {}
-    
+
     # most FS will use default walking algorithms
     walker_class=Walker
 
@@ -404,6 +404,32 @@ def exists(self, path):
         else:
             return True
 
+    def extract(self, path, file, **options):
+        """Copies a file from the filesystem to an binary file-like
+        object.
+
+        This may be more efficient that opening and copying files
+        manually if the filesystem supplies an optimized method.
+
+        Arguments:
+            path (str): Path to a resource
+            file (file-link): A file-like object open for writing in
+                binary mode.
+            options: Implementation specific options required to open
+                the source file.
+
+        Note that the file object ``file`` will *not* be closed by this
+        method. Take care to close it after this method completes
+        (ideally with a context manager).
+
+         Example:
+            >>> with open('starwars.mov', 'wb') as write_file:
+            ...     my_fs.extract('starwars.mov', write_file)
+
+        """
+        with self.openbin(path, **options) as read_file:
+            tools.copy_file_data(read_file, file)
+
     def filterdir(self,
                   path,
                   files=None,
diff --git a/fs/test.py b/fs/test.py
index 4e3be148..f2fda2b8 100644
--- a/fs/test.py
+++ b/fs/test.py
@@ -520,6 +520,16 @@ def test_exists(self):
         self.assertTrue(self.fs.exists('/'))
         self.assertTrue(self.fs.exists(''))
 
+    def test_extract(self):
+        test_bytes = b'Hello, World'
+        self.fs.setbytes('hello.bin', test_bytes)
+        write_file = io.BytesIO()
+        self.fs.extract('hello.bin', write_file)
+        self.assertEqual(write_file.getvalue(), test_bytes)
+
+        with self.assertRaises(errors.ResourceNotFound):
+            self.fs.extract('foo.bin', write_file)
+
     def test_listdir(self):
         # Check listing directory that doesn't exist
         with self.assertRaises(errors.ResourceNotFound):
diff --git a/tests/test_ftpfs.py b/tests/test_ftpfs.py
index 92e43dbd..6a137ae9 100644
--- a/tests/test_ftpfs.py
+++ b/tests/test_ftpfs.py
@@ -79,7 +79,6 @@ def test_manager(self):
             with ftp_errors(mem_fs):
                 raise error_perm('999 foo')
 
-
 class TestFTPFS(FSTestCases, unittest.TestCase):
 
     user = 'user'