utf-8-sig encoding for csv/tsv (for excel).

Fixes #18.

tablib/formats/_csv.py

@@ -3,10 +3,6 @@
 """ Tablib - CSV Support.
 """
 
-
-import os
-
-import tablib
 from tablib.compat import is_py3, csv, StringIO
 
 
@@ -14,7 +10,7 @@ title = 'csv'
 extentions = ('csv',)
 
 
-DEFAULT_ENCODING = 'utf-8'
+DEFAULT_ENCODING = 'utf-8-sig'
 
 
 
@@ -53,7 +49,7 @@ def import_set(dset, in_stream, headers=True):
 def detect(stream):
     """Returns True if given stream is valid CSV."""
     try:
-        rows = dialect = csv.Sniffer().sniff(stream)
+        csv.Sniffer().sniff(stream)
         return True
     except csv.Error:
         return False

tablib/formats/_tsv.py

@@ -3,9 +3,6 @@
 """ Tablib - TSV (Tab Separated Values) Support.
 """
 
-import os
-
-import tablib
 from tablib.compat import is_py3, csv, StringIO
 
 
@@ -13,16 +10,17 @@ from tablib.compat import is_py3, csv, StringIO
 title = 'tsv'
 extentions = ('tsv',)
 
-DEFAULT_ENCODING = 'utf-8'
+DEFAULT_ENCODING = 'utf-8-sig'
 
 def export_set(dataset):
     """Returns a TSV representation of Dataset."""
+
     stream = StringIO()
 
     if is_py3:
-        _tsv = csv.writer(stream, delimiter="\t")
+        _tsv = csv.writer(stream, delimiter='\t')
     else:
-        _tsv = csv.writer(stream, encoding=DEFAULT_ENCODING, delimiter="\t")
+        _tsv = csv.writer(stream, encoding=DEFAULT_ENCODING, delimiter='\t')
 
     for row in dataset._package(dicts=False):
         _tsv.writerow(row)
@@ -32,6 +30,7 @@ def export_set(dataset):
 
 def import_set(dset, in_stream, headers=True):
     """Returns dataset from TSV stream."""
+
     dset.wipe()
 
     if is_py3:
@@ -54,7 +53,7 @@ def import_set(dset, in_stream, headers=True):
 def detect(stream):
     """Returns True if given stream is valid TSV."""
     try:
-        rows = dialect = csv.Sniffer().sniff(stream, delimiters='\t')
+        csv.Sniffer().sniff(stream, delimiters='\t')
         return True
     except csv.Error:
         return False