View difference between Paste ID: eHjWaDsN and kUyFAE0X

 #!/usr/bin/python3
 
 import re
 import sys
 #import pdb
 
 
 def main():
     #pdb.set_trace()
     pattern = re.compile(r"\s*((ALTER_ME_IN_THE_NEW_FILE.*),.*\);)");
-        line_list = []
+    replacement = r"#ifdef F1\n" \
                   "\1\n" \
-            for line in fhandle:
+                  "#else\n" \
-                if "ALTER_ME_IN_THE NEW_FILE" in line:
+                  "\2);\n" \
-                    new_line_to_insert = re.sub(",.*", ");", line)
+                  "#endif"
-                    newlines = (
+
-                        "#ifdef F1\n",
+
-                        line,
+
-                        "#else\n",
+            orig = fhandle.read()
-                        new_line_to_insert,
+            repl, changed = re.subn(pattern, replacement, orig)
-                        "#endif\n",
+            if changed:
-                    )
+                fhandle.seek(0)
-                    line_list.extend(newlines)
+                fhandle.write(repl)
-                else:
+
-                    line_list.append(line)
+
-            fhandle.seek(0)
+
-            fhandle.writelines(line_list)
+
 if __name__ == '__main__':
     main()