我有一个谓词列表
public List<Func<Album, bool>> Predicates { get; set; }
我想检查列表是否包含特定谓词。
我的工作是：
bool check = Predicates.Contains(x=>x.AlbumName == "Winter");
但即使列表中有这样的谓词，这也总是返回false。我认为这是因为谓词是匿名方法，每种方法都是独一无二的，但仍然可以以某种方式比较它们吗？
答案 0 :(得分：5)
我担心答案基本上是＆＃34;没有＆＃34;。如果你有表达式树而不是委托，那么你可以可能比较那些努力，但基本上你已经引用了不同的方法。您需要检查方法中的IL，以比较它们是否相同。
当然，如果你有一组谓词运行的对象，你可以发现你是否有任何谓词与你的＆＃34; target＆＃34;相匹配的子集。谓词，但这与测试谓词实际上是否相同并不相同。
答案 1 :(得分：0)
切换到 表达式来; FUNC＆LT;专辑，布尔＆gt;＆gt;名单 并创建自定义比较器
答案 2 :(得分：0)
完全可以进行谓词比较。您做错了，您正在使用lambda表达式，基本上是为每个谓词声明新方法（并对其进行比较）！ ：）
使用正常函数代替lambda。
例如，声明：[Fri Feb 15 09:49:15.899753 2019] [wsgi:error] [pid 2489] GETTING NEW TEST
[Fri Feb 15 09:49:15.957897 2019] [wsgi:error] [pid 2489] Saving the test dictionary
[Fri Feb 15 09:49:16.006470 2019] [wsgi:error] [pid 2489] Internal Server Error: /test/addohm/
[Fri Feb 15 09:49:16.006506 2019] [wsgi:error] [pid 2489] Traceback (most recent call last):
[Fri Feb 15 09:49:16.006509 2019] [wsgi:error] [pid 2489] File "/path/to/website/venv/lib/python3.5/site-packages/django/core/handlers/exception.py", line 34, in in$
[Fri Feb 15 09:49:16.006511 2019] [wsgi:error] [pid 2489] response = get_response(request)
[Fri Feb 15 09:49:16.006514 2019] [wsgi:error] [pid 2489] File "/path/to/website/venv/lib/python3.5/site-packages/django/core/handlers/base.py", line 126, in _get_r$
[Fri Feb 15 09:49:16.006517 2019] [wsgi:error] [pid 2489] response = self.process_exception_by_middleware(e, request)
[Fri Feb 15 09:49:16.006520 2019] [wsgi:error] [pid 2489] File "/path/to/website/venv/lib/python3.5/site-packages/django/core/handlers/base.py", line 124, in _get_r$
[Fri Feb 15 09:49:16.006522 2019] [wsgi:error] [pid 2489] response = wrapped_callback(request, *callback_args, **callback_kwargs)
[Fri Feb 15 09:49:16.006525 2019] [wsgi:error] [pid 2489] File "/path/to/website/duotool/main/views.py", line 125, in test
[Fri Feb 15 09:49:16.006531 2019] [wsgi:error] [pid 2489] form = TestForm(wordsdict)
[Fri Feb 15 09:49:16.006533 2019] [wsgi:error] [pid 2489] File "/path/to/website/duotool/main/forms.py", line 21, in __init__
[Fri Feb 15 09:49:16.006536 2019] [wsgi:error] [pid 2489] json.dumps(test_dict, f, indent=2, ensure_ascii=False)
[Fri Feb 15 09:49:16.006538 2019] [wsgi:error] [pid 2489] File "/usr/lib/python3.5/json/__init__.py", line 179, in dump
[Fri Feb 15 09:49:16.006541 2019] [wsgi:error] [pid 2489] fp.write(chunk)
[Fri Feb 15 09:49:16.006545 2019] [wsgi:error] [pid 2489] UnicodeEncodeError: 'ascii' codec can't encode character '\\u7ea6' in position 1: ordinal not in range(128)
[Fri Feb 15 09:49:16.006550 2019] [wsgi:error] [pid 2489]
[Fri Feb 15 09:51:36.924025 2019] [wsgi:error] [pid 2627] [client 124.9.54.252:55825] Timeout when reading response headers from daemon process 'duotool.addohm.net': /var/www/django/du$
[Fri Feb 15 09:51:43.283083 2019] [wsgi:error] [pid 2631] [client 124.9.54.252:55971] Truncated or oversized response headers received from daemon process 'duotool.addohm.net': /var/ww$
[Fri Feb 15 09:51:43.283324 2019] [wsgi:error] [pid 2630] [client 124.9.54.252:55888] Truncated or oversized response headers received from daemon process 'duotool.addohm.net': /var/ww$
[Fri Feb 15 09:53:18.572055 2019] [wsgi:error] [pid 2489] GETTING NEW TEST
[Fri Feb 15 09:53:18.631474 2019] [wsgi:error] [pid 2489] Saving the test dictionary
[Fri Feb 15 09:53:18.675315 2019] [wsgi:error] [pid 2489] Internal Server Error: /test/addohm/
[Fri Feb 15 09:53:18.675335 2019] [wsgi:error] [pid 2489] Traceback (most recent call last):
[Fri Feb 15 09:53:18.675338 2019] [wsgi:error] [pid 2489] File "/path/to/website/venv/lib/python3.5/site-packages/django/core/handlers/exception.py", line 34, in in$
[Fri Feb 15 09:53:18.675341 2019] [wsgi:error] [pid 2489] response = get_response(request)
[Fri Feb 15 09:53:18.675344 2019] [wsgi:error] [pid 2489] File "/path/to/website/venv/lib/python3.5/site-packages/django/core/handlers/base.py", line 126, in _get_r$
[Fri Feb 15 09:53:18.675347 2019] [wsgi:error] [pid 2489] response = self.process_exception_by_middleware(e, request)
[Fri Feb 15 09:53:18.675349 2019] [wsgi:error] [pid 2489] File "/path/to/website/venv/lib/python3.5/site-packages/django/core/handlers/base.py", line 124, in _get_r$
[Fri Feb 15 09:53:18.675352 2019] [wsgi:error] [pid 2489] response = wrapped_callback(request, *callback_args, **callback_kwargs)
[Fri Feb 15 09:53:18.675354 2019] [wsgi:error] [pid 2489] File "/path/to/website/duotool/main/views.py", line 125, in test
[Fri Feb 15 09:53:18.675357 2019] [wsgi:error] [pid 2489] form = TestForm(wordsdict)
[Fri Feb 15 09:53:18.675359 2019] [wsgi:error] [pid 2489] File "/path/to/website/duotool/main/forms.py", line 21, in __init__
[Fri Feb 15 09:53:18.675362 2019] [wsgi:error] [pid 2489] json.dumps(test_dict, f, indent=2, ensure_ascii=False)
[Fri Feb 15 09:53:18.675365 2019] [wsgi:error] [pid 2489] File "/usr/lib/python3.5/json/__init__.py", line 179, in dump
[Fri Feb 15 09:53:18.675367 2019] [wsgi:error] [pid 2489] fp.write(chunk)
[Fri Feb 15 09:53:18.675371 2019] [wsgi:error] [pid 2489] UnicodeEncodeError: 'ascii' codec can't encode character '\\u90fd' in position 1: ordinal not in range(128)
[Fri Feb 15 09:53:18.675376 2019] [wsgi:error] [pid 2489]
[Fri Feb 15 09:53:19.498167 2019] [wsgi:error] [pid 2652] /path/to/website/duotool
您将可以将bool AlbumNameFilter(Album album) {return album.Name == "Winter";}添加到AlbumNameFilter列表中，以后再Predicates进行添加：
Find