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[英]Get function signature and parameters from within current function in Python
[英]get function signature from FrameInfo or frame in python
在python中編寫自己的異常鈎子時,我想到了使用inspect
-module來向自己提供有關如何調用該函數的更多信息。
這意味着函數的簽名以及傳遞給它的參數 。
import inspect
frame_infos = inspect.trace() # get the FrameInfos
for f_idx, f_info in enumerate(frame_infos):
frame_dict.update(f_info.frame.f_locals) # update namespace with deeper frame levels
#Output basic Error-Information
print(f' File "{f_info.filename}", line {f_info.lineno}, in {f_info.function}')
for line in f_info.code_context:
print(f' {line.strip()}')
########################################################
# show signature and arguments 1 level deeper
if f_idx+1 < len(frame_infos):
func_name = frame_infos[f_idx+1].function #name of the function
try:
func_ref = frame_dict[func_name] # look up in namespace
sig = inspect.signature(func_ref) # call signature for function_reference
except KeyError: sig = '(signature unknown)'
print(f' {func_name} {sig}\n')
print(f' {frame_infos[f_idx+1].frame.f_locals}\n')
像這樣的基本示例可以很好地工作:
def test1 ( x: int, y: tuple = 0 )->list: # the types obviously dont match
return test2(y, b=x, help=0)
def test2 ( a, *args, b, **kwargs ):
return a + b / 0
try:
test1(5)
except: ...
輸出:
File "C:/test/errorHandler.py", line 136, in <module>
test1(5)
test1 (x:int, y:tuple=0) -> list
{'y': 0, 'x': 5}
File "C:/test/errorHandler.py", line 130, in test1
return test2(y, b=x, help=0)
test2 (a, *args, b, **kwargs)
{'kwargs': {'help': 0}, 'args': (), 'b': 5, 'a': 0}
File "C:/test/errorHandler.py", line 133, in test2
return a + b / 0
但是,一旦您離開1個文件,就無法將函數名稱映射到基本名稱空間。
file1:
import file2; try: file2.foo() except: ...
文件2import file2; try: file2.foo() except: ...
import file2; try: file2.foo() except: ...
file2:import file3; def foo(): file3.foo()
import file3; def foo(): file3.foo()
file3:def foo(): return 0/0
因此,從FrameInfo
,我正在尋找一種從FrameInfo
或frame
FrameInfo
獲取函數的方法(例如<function foo at 0x000002F4A43ACD08>
),但是我看到的唯一信息是名稱,文件和行。
(我不喜歡通過在特定行中查看源文件來獲得簽名的想法。)
到目前為止,最好的參考是Inspect
-documentation ,但是我還沒有找到有用的東西。
使用gc
(垃圾收集器)函數get_referrers()
可以搜索直接引用特定對象的所有對象。
通過框架的f_code
提供的代碼對象,您可以使用此函數查找框架以及該函數。
code_obj = frame.f_code
import gc #garbage collector
print(gc.get_referrers(code_obj))
# [<function foo at 0x0000020F758F4EA0>, <frame object at 0x0000020F75618CF8>]
因此,只需找到真正的功能就可以了:
# find the object that has __code__ and is actally the object with that specific code
[obj for obj in garbage_collector.get_referrers(code_obj)
if hasattr(obj, '__code__')
and obj.__code__ is code_obj][0]
現在您可以在過濾對象上使用inspect.signature()
。
來自gc.get_referrers(objs)
objs)的gc.get_referrers(objs)
:
此功能將僅定位那些支持垃圾收集的容器; 找不到引用其他對象但不支持垃圾回收的擴展類型。
import inspect
import gc
def ERROR_Printer_Inspection ( stream = sys.stderr ) :
"""
called in try: except: <here>
prints the last error-traceback in the given "stream"
includes signature and function arguments if possible
"""
stream.write('Traceback (most recent call last):\n')
etype, value, _ = sys.exc_info() # get type and value for last line of output
frame_infos = inspect.trace() # get frames for source-lines and arguments
for f_idx, f_info in enumerate(frame_infos):
stream.write(f' File "{f_info.filename}", line {f_info.lineno}, in {f_info.function}\n')
for line in f_info.code_context: # print location and code parts
stream.write(f' {line.lstrip()}')
if f_idx+1 < len(frame_infos): # signature and arguments
code_obj = frame_infos[f_idx+1].frame.f_code # codeobject from next frame
function_obj = [obj for obj in gc.get_referrers(code_obj) if hasattr(obj, '__code__') and obj.__code__ is code_obj]
if function_obj: # found some matching object
function_obj=function_obj[0] # function_object
func_name = frame_infos[f_idx + 1].function # name
stream.write(f' > {func_name} {inspect.signature(function_obj)}\n')
next_frame_locals = frame_infos[f_idx+1].frame.f_locals # calling arguments
# filter them to the "calling"-arguments
arguments = dict((key, next_frame_locals[key]) for key in code_obj.co_varnames if key in next_frame_locals.keys())
stream.write(f' -> {str(arguments)[1:-1]}\n')
stream.write(f'{etype.__name__}: {value}\n')
stream.flush()
如果在函數啟動后對其進行編輯,則顯示“調用”參數可能會誤導用戶:
def foo (a, b, **kwargs):
del a, kwargs
b = 'fail'
return 0/0
try: foo(0, 1, test=True)
except: ERROR_Printer_Inspection()
輸出:
Traceback (most recent call last):
File "C:/test/errorHandler.py", line 142, in <module>
try: foo(0, 1, test=True)
> foo (a, b, **kwargs)
-> 'b': 'fail'
File "C:/test/errorHandler.py", line 140, in foo
return 0 / 0
ZeroDivisionError: division by zero
您無法相信,但這是另一個問題。
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