diff --git a/generator.py b/generator.py
index b9aaee942..d2c9bdaf8 100755
--- a/generator.py
+++ b/generator.py
@@ -1,58 +1,101 @@
 #!/usr/bin/env python3
 
 from os import listdir
-from os.path import isfile, join
-from subprocess import call
+from os.path import isfile, isdir, join
+import subprocess
 import sys
 
-need_rebuild = False
 
-def update_workspace():
-    try:
-        call(['bash', '-c', 'cd gir && cargo build --release'])
-    except:
+NOTHING_TO_BE_DONE = 0
+NEED_UPDATE = 1
+FAILURE = 2
+
+
+def run_command(command, folder=None):
+    if folder is None:
+        folder = "."
+    child = subprocess.Popen(command, cwd=folder)
+    child.communicate()
+    if child.returncode != 0:
+        print("Command `{}` failed with return code `{}`...".format(command, child.returncode))
         return False
     return True
 
 
-if not isfile('./gir/src'):
-    need_rebuild = True
+def update_workspace():
+    try:
+        return run_command(['cargo', 'build', '--release'], 'gir')
+    except:
+        return False
+
+
+def def_check_submodule(submodule_path):
+    if len(listdir(submodule_path)) != 0:
+        return NOTHING_TO_BE_DONE
     print('=> Initializing gir submodule...')
-    call(['bash', '-c', 'git submodule update --init'])
+    if not run_command(['git', 'submodule', 'update', '--init']):
+        return FAILURE
     print('<= Done!')
 
-question = 'Do you want to update gir submodule? [y/N] '
-if sys.version_info[0] < 3:
-    line = raw_input(question)
-else:
-    line = input(question)
-line = line.strip()
-if line.lower() == 'y':
-    need_rebuild = True
-    print('=> Updating gir submodule...')
-    call(['bash', '-c', 'cd gir && git reset --hard HEAD && git pull -f origin master'])
-    print('<= Done!')
-
-if need_rebuild is True or not os.path.isfile('./gir/target/release/gir'):
-    print('=> Building gir...')
-    if update_workspace() is True:
-        print('<= Done!')
+    question = 'Do you want to update gir submodule? [y/N] '
+    if sys.version_info[0] < 3:
+        line = raw_input(question)
     else:
-        print('<= Failed...')
-        sys.exit(1)
+        line = input(question)
+    line = line.strip()
+    if line.lower() == 'y':
+        print('=> Updating gir submodule...')
+        if not run_command(['git', 'reset', '--hard', 'HEAD'], 'gir'):
+            return FAILURE
+        if not run_command(['git', 'pull', '-f', 'origin', 'master'], 'gir'):
+            return FAILURE
+        print('<= Done!')
+        return NEED_UPDATE
+    return NOTHING_TO_BE_DONE
 
-print('=> Regenerating crates...')
-for entry in [f for f in listdir('.') if isfile(join('.', f))]:
-    if entry.startswith('Gir_Gst') and entry.endswith('.toml'):
-        print('==> Regenerating "{}"...'.format(entry))
-        try:
-            call(['./gir/target/release/gir', '-c', entry])
-        except Exception as err:
-            print('The following error occurred: {}'.format(err))
-            line = input('Do you want to continue? [y/N] ').strip().lower()
-            if line != 'y':
-                sys.exit(1)
-        print('<== Done!')
-call(['cargo', 'fmt'])
-print('<= Done!')
-print("Don't forget to check if everything has been correctly generated!")
+
+def build_gir_if_needed(updated_submodule):
+    if updated_submodule == FAILURE:
+        return False
+    elif updated_submodule == NEED_UPDATE or not isfile('./gir/target/release/gir'):
+        print('=> Building gir...')
+        if update_workspace() is True:
+            print('<= Done!')
+        else:
+            print('<= Failed...')
+            return False
+    return True
+
+
+def regen_crates():
+    for entry in [f for f in listdir('.') if isfile(join('.', f))]:
+        if entry.startswith('Gir_Gst') and entry.endswith('.toml'):
+            print('==> Regenerating "{}"...'.format(entry))
+            try:
+                run_command(['./gir/target/release/gir', '-c', entry])
+            except Exception as err:
+                print('The following error occurred: {}'.format(err))
+                line = input('Do you want to continue? [y/N] ').strip().lower()
+                if line != 'y':
+                    sys.exit(1)
+            print('<== Done!')
+
+
+def main():
+    if def_check_submodule("gir-files") == FAILURE:
+        return 1
+    if not build_gir_if_needed(def_check_submodule("gir")):
+        return 1
+
+    print('=> Regenerating crates...')
+    if not regen_crates():
+        return 1
+    if not run_command(['cargo', 'fmt']):
+        return 1
+    print('<= Done!')
+    print("Don't forget to check if everything has been correctly generated!")
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())