Last active
April 12, 2023 23:52
-
-
Save arccoder/27609d200612babf11fb09f713a15c33 to your computer and use it in GitHub Desktop.
Python: Read only dictionary
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| class ReadOnlyDict(dict): | |
| def __setitem__(self, key, value): | |
| raise RuntimeError("Modification not supported") | |
| rw_dict = {'key': 'original'} | |
| print('Dict: ' + str(rw_dict)) | |
| ro_dict = ReadOnlyDict(rw_dict) | |
| print('ReadOnlyDict: ' + str(ro_dict)) | |
| rw_dict['key'] = 'modified' | |
| print('Dict: ' + str(rw_dict)) | |
| ro_dict['key'] = 'modified' # RuntimeError: Modification not supported | |
| print('ReadOnlyDict: ' + str(ro_dict)) |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| import copy | |
| def method(in_dict): | |
| print('Method: ' + str(in_dict)) | |
| in_dict['key'] = 'modified' | |
| print('Method: ' + str(in_dict)) | |
| rw_dict = {'key': 'original'} | |
| print('Original: ' + str(rw_dict)) | |
| method(copy.deepcopy(rw_dict)) | |
| print('Original: ' + str(rw_dict)) |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| from types import MappingProxyType | |
| rw_dict = {'key': 'original'} | |
| ro_dict = MappingProxyType(rw_dict) | |
| # ro_dict['key'] = 'modified' # TypeError: 'mappingproxy' object does not support item assignment | |
| rw_dict['key'] = 'modified' | |
| print(ro_dict) # Output: {'key': 'modified'} |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| import threading | |
| import time | |
| from types import MappingProxyType | |
| def thread_function(name, in_dict): | |
| print("Thread %s: starting" % name) | |
| print("Thread %s: %s" % (name, str(in_dict))) | |
| print("Thread %s: wait for 5 seconds" % name) | |
| time.sleep(5) | |
| print("Thread %s: %s" % (name, str(in_dict))) | |
| print("Thread %s: finishing" % name) | |
| # in_dict['key'] = 'modified' # TypeError: 'mappingproxy' object does not support item assignment | |
| if __name__ == "__main__": | |
| rw_dict = {'key': 'original'} | |
| ro_dict = MappingProxyType(rw_dict) | |
| print("Main : " + str(ro_dict)) | |
| print("Main : before creating thread") | |
| x = threading.Thread(target=thread_function, args=(1, ro_dict,)) | |
| print("Main : before running thread") | |
| x.start() | |
| print("Main : wait for 2 seconds") | |
| time.sleep(2) | |
| rw_dict['key'] = 'modified' # Modify value | |
| print("Main : " + str(ro_dict)) | |
| print("Main : wait for the thread to finish") | |
| # x.join() | |
| print("Main : all done") |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment