追蹤或跟蹤 Python 語句執行(跟蹤)
Python 庫中 'trace' 模組中的函式生成程式執行的跟蹤,以及帶註釋的語句覆蓋率。它還具有透過生成呼叫者關係來列出執行期間呼叫的函式的功能。
以下兩個 Python 指令碼用作示例來演示 trace 模組的功能。
#myfunctions.py import math def area(x): a = math.pi*math.pow(x,2) return a def factorial(x): if x==1: return 1 else: return x*factorial(x-1)
#mymain.py import myfunctions def main(): x = 5 print ('area=',myfunctions.area(x)) print ('factorial=',myfunctions.factorial(x)) if __name__=='__main__': main()
'trace' 模組具有命令列介面。模組中的所有函式都可以使用命令列開關呼叫。最重要的選項是 **--trace**,它在執行時顯示程式行。在以下示例中,使用了另一個選項 **--ignore-dir**。它在生成跟蹤時忽略指定的目錄。
E:\python37>python -m trace --ignore-dir=../lib --trace mymain.py
輸出
mymain.py(2): def main(): mymain.py(7): if __name__=='__main__': mymain.py(8): main() --- modulename: mymain, funcname: main mymain.py(3): x=5 mymain.py(4): print ('area=',myfunctions.area(x)) --- modulename: myfunctions, funcname: area myfunctions.py(3): a=math.pi*math.pow(x,2) myfunctions.py(4): return a area= 78.53981633974483 mymain.py(5): print ('factorial=',myfunctions.factorial(x)) --- modulename: myfunctions, funcname: factorial myfunctions.py(6): if x==1: myfunctions.py(9): return x*factorial(x-1) --- modulename: myfunctions, funcname: factorial myfunctions.py(6): if x==1: myfunctions.py(9): return x*factorial(x-1) --- modulename: myfunctions, funcname: factorial myfunctions.py(6): if x==1: myfunctions.py(9): return x*factorial(x-1) --- modulename: myfunctions, funcname: factorial myfunctions.py(6): if x==1: myfunctions.py(9): return x*factorial(x-1) --- modulename: myfunctions, funcname: factorial myfunctions.py(6): if x==1: myfunctions.py(7): return 1 factorial= 120
**--count** 選項為每個正在使用的模組生成一個檔案,副檔名為 cover。
E:\python37>python -m trace --count mymain.py area= 78.53981633974483 factorial = 120
myfunctions.cover
1: import math 1: def area(x): 1: a = math.pi*math.pow(x,2) 1: return a 1: def factorial(x): 5: if x==1: 1: return 1 else: 4: return x*factorial(x-1)
mymain.cover
1: import myfunctions 1: def main(): 1: x = 5 1: print ('area=',myfunctions.area(x)) 1: print ('factorial=',myfunctions.factorial(x)) 1: if __name__=='__main__': 1: main()
如果還使用了 –count 選項,則 **--summary** 選項會顯示簡要摘要。
E:\python37>python -m trace --count --summary mymain.py area = 78.53981633974483 factorial = 120 lines cov% module (path) 8 100% myfunctions (E:\python37\myfunctions.py) 7 100% mymain (mymain.py)
**--file** 選項指定累積多次跟蹤執行計數的檔案的名稱。
E:\python37>python -m trace --count --file report.txt mymain.py area = 78.53981633974483 factorial = 120 Skipping counts file 'report.txt': [Errno 2] No such file or directory: 'report.txt' E:\python37>python -m trace --count --file report.txt mymain.py area= 78.53981633974483 factorial= 120
**--listfuncs** 選項顯示程式執行期間呼叫的函式。
E:\python37>python -m trace --listfunc mymain.py | findstr -v importlib area= 78.53981633974483 factorial= 120 functions called: filename: E:\python37\lib\encodings\cp1252.py, modulename: cp1252, funcname: IncrementalEncoder.encode filename: E:\python37\myfunctions.py, modulename: myfunctions, funcname: <module> filename: E:\python37\myfunctions.py, modulename: myfunctions, funcname: area filename: E:\python37\myfunctions.py, modulename: myfunctions, funcname: factorial filename: mymain.py, modulename: mymain, funcname: <module> filename: mymain.py, modulename: mymain, funcname: main
**--trackcalls** 選項與 –list funcs 選項一起使用。它生成呼叫關係。
E:\python37>python -m trace --listfunc --trackcalls mymain.py | findstr -v importlib area= 78.53981633974483 factorial= 120 calling relationships: --> E:\python37\myfunctions.py *** E:\python37\lib\trace.py *** --> mymain.py trace.Trace.runctx -> mymain.<module> *** E:\python37\myfunctions.py *** myfunctions.factorial -> myfunctions.factorial *** mymain.py *** mymain.<module> -> mymain.main --> E:\python37\lib\encodings\cp1252.py mymain.main -> cp1252.IncrementalEncoder.encode --> E:\python37\myfunctions.py mymain.main -> myfunctions.area mymain.main -> myfunctions.factorial
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