Merge #10781: Python cleanups

7821458 Use for-loop instead of list comprehension (practicalswift)
8239794 Use the variable name _ for unused return values (practicalswift)
2e6080b Remove unused variables and/or function calls (practicalswift)
9b94054 Avoid reference to undefined name: stderr does not exist, sys.stderr does (practicalswift)
51cb6b8 Use print(...) instead of undefined printf(...) (practicalswift)
25cd520 Use sys.exit(...) instead of exit(...): exit(...) should not be used in programs (practicalswift)

Pull request description:

  Python cleanups:
  * Avoid reference to undefined name: `stderr` does not exist, `sys.stderr` does
  * Use `print(...)` instead of undefined `printf(...)`
  * Avoid redefinition of variable (`tx`) in list comprehension
  * Remove unused variables and/or function calls
  * Use `sys.exit(...)` instead of `exit(...)`: [`exit(...)` should not be used in programs](bitcoin/bitcoin#10753 (comment))

Tree-SHA512: 1238dfbc1d20f7edadea5e5406a589f293065638f6234809f0d5b6ba746dffe3d276bc5884c7af388a6c798c61a8759faaccf57f381225644754c0f61914eb4b

Author: MarcoFalke

contrib/devtools/check-doc.py

@@ -12,6 +12,7 @@
 
 from subprocess import check_output
 import re
+import sys
 
 FOLDER_GREP = 'src'
 FOLDER_TEST = 'src/test/'
@@ -39,7 +40,7 @@ def main():
   print "Args unknown     : %s" % len(args_unknown)
   print args_unknown
 
-  exit(len(args_need_doc))
+  sys.exit(len(args_need_doc))
 
 if __name__ == "__main__":
     main()

contrib/devtools/github-merge.py

@@ -20,6 +20,7 @@
 import argparse
 import hashlib
 import subprocess
+import sys
 import json,codecs
 try:
     from urllib.request import Request,urlopen
@@ -158,11 +159,11 @@ def main():
     if repo is None:
         print("ERROR: No repository configured. Use this command to set:", file=stderr)
         print("git config githubmerge.repository <owner>/<repo>", file=stderr)
-        exit(1)
+        sys.exit(1)
     if signingkey is None:
         print("ERROR: No GPG signing key set. Set one using:",file=stderr)
         print("git config --global user.signingkey <key>",file=stderr)
-        exit(1)
+        sys.exit(1)
 
     host_repo = host+":"+repo # shortcut for push/pull target
 
@@ -173,7 +174,7 @@ def main():
     # Receive pull information from github
     info = retrieve_pr_info(repo,pull)
     if info is None:
-        exit(1)
+        sys.exit(1)
     title = info['title'].strip()
     body = info['body'].strip()
     # precedence order for destination branch argument:
@@ -194,27 +195,27 @@ def main():
         subprocess.check_call([GIT,'checkout','-q',branch])
     except subprocess.CalledProcessError as e:
         print("ERROR: Cannot check out branch %s." % (branch), file=stderr)
-        exit(3)
+        sys.exit(3)
     try:
         subprocess.check_call([GIT,'fetch','-q',host_repo,'+refs/pull/'+pull+'/*:refs/heads/pull/'+pull+'/*'])
     except subprocess.CalledProcessError as e:
         print("ERROR: Cannot find pull request #%s on %s." % (pull,host_repo), file=stderr)
-        exit(3)
+        sys.exit(3)
     try:
         subprocess.check_call([GIT,'log','-q','-1','refs/heads/'+head_branch], stdout=devnull, stderr=stdout)
     except subprocess.CalledProcessError as e:
         print("ERROR: Cannot find head of pull request #%s on %s." % (pull,host_repo), file=stderr)
-        exit(3)
+        sys.exit(3)
     try:
         subprocess.check_call([GIT,'log','-q','-1','refs/heads/'+merge_branch], stdout=devnull, stderr=stdout)
     except subprocess.CalledProcessError as e:
         print("ERROR: Cannot find merge of pull request #%s on %s." % (pull,host_repo), file=stderr)
-        exit(3)
+        sys.exit(3)
     try:
         subprocess.check_call([GIT,'fetch','-q',host_repo,'+refs/heads/'+branch+':refs/heads/'+base_branch])
     except subprocess.CalledProcessError as e:
         print("ERROR: Cannot find branch %s on %s." % (branch,host_repo), file=stderr)
-        exit(3)
+        sys.exit(3)
     subprocess.check_call([GIT,'checkout','-q',base_branch])
     subprocess.call([GIT,'branch','-q','-D',local_merge_branch], stderr=devnull)
     subprocess.check_call([GIT,'checkout','-q','-b',local_merge_branch])
@@ -236,30 +237,30 @@ def main():
         except subprocess.CalledProcessError as e:
             print("ERROR: Cannot be merged cleanly.",file=stderr)
             subprocess.check_call([GIT,'merge','--abort'])
-            exit(4)
+            sys.exit(4)
         logmsg = subprocess.check_output([GIT,'log','--pretty=format:%s','-n','1']).decode('utf-8')
         if logmsg.rstrip() != firstline.rstrip():
             print("ERROR: Creating merge failed (already merged?).",file=stderr)
-            exit(4)
+            sys.exit(4)
 
         symlink_files = get_symlink_files()
         for f in symlink_files:
             print("ERROR: File %s was a symlink" % f)
         if len(symlink_files) > 0:
-            exit(4)
+            sys.exit(4)
 
         # Put tree SHA512 into the message
         try:
             first_sha512 = tree_sha512sum()
             message += '\n\nTree-SHA512: ' + first_sha512
         except subprocess.CalledProcessError as e:
-            printf("ERROR: Unable to compute tree hash")
-            exit(4)
+            print("ERROR: Unable to compute tree hash")
+            sys.exit(4)
         try:
             subprocess.check_call([GIT,'commit','--amend','-m',message.encode('utf-8')])
         except subprocess.CalledProcessError as e:
-            printf("ERROR: Cannot update message.",file=stderr)
-            exit(4)
+            print("ERROR: Cannot update message.", file=stderr)
+            sys.exit(4)
 
         print_merge_details(pull, title, branch, base_branch, head_branch)
         print()
@@ -268,7 +269,7 @@ def main():
         if testcmd:
             if subprocess.call(testcmd,shell=True):
                 print("ERROR: Running %s failed." % testcmd,file=stderr)
-                exit(5)
+                sys.exit(5)
 
             # Show the created merge.
             diff = subprocess.check_output([GIT,'diff',merge_branch+'..'+local_merge_branch])
@@ -279,7 +280,7 @@ def main():
                 if reply.lower() == 'ignore':
                     print("Difference with github ignored.",file=stderr)
                 else:
-                    exit(6)
+                    sys.exit(6)
         else:
             # Verify the result manually.
             print("Dropping you on a shell so you can try building/testing the merged source.",file=stderr)
@@ -292,7 +293,7 @@ def main():
         second_sha512 = tree_sha512sum()
         if first_sha512 != second_sha512:
             print("ERROR: Tree hash changed unexpectedly",file=stderr)
-            exit(8)
+            sys.exit(8)
 
         # Sign the merge commit.
         print_merge_details(pull, title, branch, base_branch, head_branch)
@@ -306,7 +307,7 @@ def main():
                     print("Error while signing, asking again.",file=stderr)
             elif reply == 'x':
                 print("Not signing off on merge, exiting.",file=stderr)
-                exit(1)
+                sys.exit(1)
 
         # Put the result in branch.
         subprocess.check_call([GIT,'checkout','-q',branch])
@@ -326,7 +327,7 @@ def main():
             subprocess.check_call([GIT,'push',host_repo,'refs/heads/'+branch])
             break
         elif reply == 'x':
-            exit(1)
+            sys.exit(1)
 
 if __name__ == '__main__':
     main()

contrib/devtools/security-check.py

@@ -212,5 +212,5 @@ def identify_executable(executable):
         except IOError:
             print('%s: cannot open' % filename)
             retval = 1
-    exit(retval)
+    sys.exit(retval)
 

contrib/devtools/symbol-check.py

@@ -159,6 +159,6 @@ def read_libraries(filename):
                 print('%s: NEEDED library %s is not allowed' % (filename, library_name.decode('utf-8')))
                 retval = 1
 
-    exit(retval)
+    sys.exit(retval)
 
 

contrib/devtools/update-translations.py

@@ -36,12 +36,12 @@ def check_at_repository_root():
     if not os.path.exists('.git'):
         print('No .git directory found')
         print('Execute this script at the root of the repository', file=sys.stderr)
-        exit(1)
+        sys.exit(1)
 
 def fetch_all_translations():
     if subprocess.call([TX, 'pull', '-f', '-a']):
         print('Error while fetching translations', file=sys.stderr)
-        exit(1)
+        sys.exit(1)
 
 def find_format_specifiers(s):
     '''Find all format specifiers in a string.'''

contrib/linearize/linearize-hashes.py

@@ -87,7 +87,7 @@ def get_block_hashes(settings, max_blocks_per_call=10000):
 		for x,resp_obj in enumerate(reply):
 			if rpc.response_is_error(resp_obj):
 				print('JSON-RPC: error at height', height+x, ': ', resp_obj['error'], file=sys.stderr)
-				exit(1)
+				sys.exit(1)
 			assert(resp_obj['id'] == x) # assume replies are in-sequence
 			if settings['rev_hash_bytes'] == 'true':
 				resp_obj['result'] = hex_switchEndian(resp_obj['result'])
@@ -140,7 +140,7 @@ def get_rpc_cookie():
 	if 'datadir' in settings and not use_userpass:
 		use_datadir = True
 	if not use_userpass and not use_datadir:
-		print("Missing datadir or username and/or password in cfg file", file=stderr)
+		print("Missing datadir or username and/or password in cfg file", file=sys.stderr)
 		sys.exit(1)
 
 	settings['port'] = int(settings['port'])

contrib/seeds/generate-seeds.py

@@ -114,7 +114,7 @@ def process_nodes(g, f, structname, defaultport):
 def main():
     if len(sys.argv)<2:
         print(('Usage: %s <path_to_nodes_txt>' % sys.argv[0]), file=sys.stderr)
-        exit(1)
+        sys.exit(1)
     g = sys.stdout
     indir = sys.argv[1]
     g.write('#ifndef BITCOIN_CHAINPARAMSSEEDS_H\n')

contrib/zmq/zmq_sub.py

@@ -32,7 +32,7 @@
 
 if not (sys.version_info.major >= 3 and sys.version_info.minor >= 5):
     print("This example only works with Python 3.5 and greater")
-    exit(1)
+    sys.exit(1)
 
 port = 28332
 

contrib/zmq/zmq_sub3.4.py

@@ -36,7 +36,7 @@
 
 if not (sys.version_info.major >= 3 and sys.version_info.minor >= 4):
     print("This example only works with Python 3.4 and greater")
-    exit(1)
+    sys.exit(1)
 
 port = 28332
 

share/qt/extract_strings_qt.py

@@ -58,7 +58,7 @@ def parse_po(text):
 if not XGETTEXT:
     print('Cannot extract strings: xgettext utility is not installed or not configured.',file=sys.stderr)
     print('Please install package "gettext" and re-run \'./configure\'.',file=sys.stderr)
-    exit(1)
+    sys.exit(1)
 child = Popen([XGETTEXT,'--output=-','-n','--keyword=_'] + files, stdout=PIPE)
 (out, err) = child.communicate()