file i/o: use 'with' keyword

contrib/make_locale

@@ -23,7 +23,8 @@ crowdin_api_key = None
 
 filename = '~/.crowdin_api_key'
 if os.path.exists(filename):
-    crowdin_api_key = open(filename).read().strip()
+    with open(filename) as f:
+        crowdin_api_key = f.read().strip()
 
 if "crowdin_api_key" in os.environ:
     crowdin_api_key = os.environ["crowdin_api_key"]
@@ -32,8 +33,9 @@ if crowdin_api_key:
     # Push to Crowdin
     print('Push to Crowdin')
     url = ('https://api.crowdin.com/api/project/' + crowdin_identifier + '/update-file?key=' + crowdin_api_key)
-    files = {crowdin_file_name: open(locale_file_name,'rb')}
-    requests.request('POST', url, files=files)
+    with open(locale_file_name,'rb') as f:
+        files = {crowdin_file_name: f}
+        requests.request('POST', url, files=files)
     # Build translations
     print('Build translations')
     response = requests.request('GET', 'https://api.crowdin.com/api/project/' + crowdin_identifier + '/export?key=' + crowdin_api_key).content
@@ -52,9 +54,8 @@ for name in zfobj.namelist():
         if not os.path.exists(name[16:]):
             os.mkdir(name[16:])
     else:
-        output = open(name[16:], 'wb')
-        output.write(zfobj.read(name))
-        output.close()
+        with open(name[16:], 'wb') as output:
+            output.write(zfobj.read(name))
 
 # Convert .po to .mo
 print('Installing')

gui/qt/main_window.py

@@ -2235,9 +2235,8 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, PrintError):
         labelsFile = self.getOpenFileName(_("Open labels file"), "*.json")
         if not labelsFile: return
         try:
-            f = open(labelsFile, 'r')
-            data = f.read()
-            f.close()
+            with open(labelsFile, 'r') as f:
+                data = f.read()
             for key, value in json.loads(data).items():
                 self.wallet.set_label(key, value)
             self.show_message(_("Your labels were imported from") + " '%s'" % str(labelsFile))

lib/bitcoin.py

@@ -41,7 +41,8 @@ from . import segwit_addr
 def read_json_dict(filename):
     path = os.path.join(os.path.dirname(__file__), filename)
     try:
-        r = json.loads(open(path, 'r').read())
+        with open(path, 'r') as f:
+            r = json.loads(f.read())
     except:
         r = {}
     return r

lib/blockchain.py

@@ -247,10 +247,9 @@ class Blockchain(util.PrintError):
         delta = height - self.checkpoint
         name = self.path()
         if os.path.exists(name):
-            f = open(name, 'rb')
-            f.seek(delta * 80)
-            h = f.read(80)
-            f.close()
+            with open(name, 'rb') as f:
+                f.seek(delta * 80)
+                h = f.read(80)
         return deserialize_header(h, height)
 
     def get_hash(self, height):

lib/exchange_rate.py

@@ -339,7 +339,8 @@ def get_exchanges_and_currencies():
     import os, json
     path = os.path.join(os.path.dirname(__file__), 'currencies.json')
     try:
-        return json.loads(open(path, 'r').read())
+        with open(path, 'r') as f:
+            return json.loads(f.read())
     except:
         pass
     d = {}

lib/mnemonic.py

@@ -98,7 +98,8 @@ def normalize_text(seed):
 
 def load_wordlist(filename):
     path = os.path.join(os.path.dirname(__file__), 'wordlist', filename)
-    s = open(path,'r').read().strip()
+    with open(path, 'r') as f:
+        s = f.read().strip()
     s = unicodedata.normalize('NFKD', s)
     lines = s.split('\n')
     wordlist = []

lib/qrscanner.py

@@ -70,7 +70,8 @@ def _find_system_cameras():
     if os.path.exists(device_root):
         for device in os.listdir(device_root):
             try:
-                name = open(os.path.join(device_root, device, 'name')).read()
+                with open(os.path.join(device_root, device, 'name')) as f:
+                    name = f.read()
             except IOError:
                 continue
             name = name.strip('\n')

lib/simple_config.py

@@ -149,9 +149,8 @@ class SimpleConfig(PrintError):
             return
         path = os.path.join(self.path, "config")
         s = json.dumps(self.user_config, indent=4, sort_keys=True)
-        f = open(path, "w")
-        f.write(s)
-        f.close()
+        with open(path, "w") as f:
+            f.write(s)
         os.chmod(path, stat.S_IREAD | stat.S_IWRITE)
 
     def get_wallet_path(self):