Download changed (#459)

* DownBytes added

* File.downbyte changed

* Changed file.download();Remove downbyte()

* Fixed typo

* add docstring, make custom_path and out mutually exclusive, rename downbytes to retrieve

* remove trailing whitespace

* run pre-commit hooks

telegram/file.py

@@ -65,17 +65,35 @@ class File(TelegramObject):
 
         return File(bot=bot, **data)
 
-    def download(self, custom_path=None):
+    def download(self, custom_path=None, out=None):
         """
-        Args:
-            custom_path (str):
+        Download this file. By default, the file is saved in the current working directory with its
+        original filename as reported by Telegram. If a ``custom_path`` is supplied, it will be
+        saved to that path instead. If ``out`` is defined, the file contents will be saved to that
+        object using the ``out.write`` method. ``custom_path`` and ``out`` are mutually exclusive.
 
+        Keyword Args:
+            custom_path (Optional[str]): Custom path.
+            out (Optional[object]): A file-like object. Must be opened in binary mode, if
+                applicable.
+
+        Raises:
+            ValueError: If both ``custom_path`` and ``out`` are passed.
         """
+
+        if custom_path is not None and out is not None:
+            raise ValueError('custom_path and out are mutually exclusive')
+
         url = self.file_path
 
-        if custom_path:
-            filename = custom_path
-        else:
-            filename = basename(url)
+        if out:
+            buf = self.bot.request.retrieve(url)
+            out.write(buf)
 
-        self.bot.request.download(url, filename)
+        else:
+            if custom_path:
+                filename = custom_path
+            else:
+                filename = basename(url)
+
+            self.bot.request.download(url, filename)

telegram/utils/request.py

@@ -208,6 +208,14 @@ class Request(object):
 
         return self._parse(result)
 
+    def retrieve(self, url):
+        """Retrieve the contents of a file by its URL.
+        Args:
+          url:
+            The web location we want to retrieve.
+        """
+        return self._request_wrapper('GET', url)
+
     def download(self, url, filename):
         """Download a file by its URL.
         Args:
@@ -218,6 +226,6 @@ class Request(object):
             The filename within the path to download the file.
 
         """
-        buf = self._request_wrapper('GET', url)
+        buf = self.retrieve(url)
         with open(filename, 'wb') as fobj:
             fobj.write(buf)