python3-notes-d-001-Exceptions and assertions

Import Sys
# ===Catching exceptions(can be flexibly combined) ===
DefEXCEP ():
 #-Try except-
 Try
 Print (ex)
 Except#Catch all exceptions
 Print"Catching exceptions!")

 Try
 Print (ex)
 Except#Get exception information by function
Types, value, back = Sys.exc_info ()#Catching exceptions
Sys.excepthook (types, value, back)#Printing exceptions

 Try
 Print (ex)
 ExceptNameerror:#Capturing the specified exception
 Print"Catch name undefined exception!")
 ExceptIOError:
 Print"CaptureIoAbnormal!")
 Except
 Print"Catch all exceptions!")

 Try
 Print (ex)
 Except (Nameerror,IOError)As e:#Capturing multiple exceptions at the same time,And tell the cause of the anomaly
 Print"Capturing multiple exceptions!")
 Print (e)
 Except
 Print"Catch all exceptions!")


 #-Try except else-
 Try
 Pass
Except
 Print"Catching exceptions!")
 Else#No exception occurs when the code block is executed
 Print"Operating normally.")

 #-Try except else finally-
 Try
 Pass
Except
 Print"Catching exceptions!")
 Else
 Print"Operating normally.")
 Finally#Executes regardless of whether an exception occurred
 Print"Executes regardless of whether an exception occurred")




# ===Custom exceptions===
# -Writing custom Exceptions-
Class Myerror (Exception):#InheritedException

#Rewrite andSuperStructure
 Def__INIT__ (Self, mes ="Throws an exception."):
 Exception.__INIT__ (Self
 Self.message = mes

 Def__STR__ (Self):
return Self.message


#- Use custom exceptions -
def Myerr ():
Try:
Raise Myerror (" throw exception !") # throws an exception
except Myerror as e: # catching exceptions
Print (e)

# ===Assertion statement===
DefAssertdemo ():
    #Assertions are typically used for testing,If the test result isFlase,Will throwAssertionerrorAbnormal
 AssertType"String")is str 
  assert 3 < 4 
  assert 4< Span style= "COLOR: #cc7832",  " throw assertionerror exception " Span style= "COLOR: #6a8759" > 
 # =======  function call  ====== 
 if __name__ =  "__main__": 
 Excep () 
 Myerr () 
 Assertdemo ()            

python3-Note-d-001-exceptions and assertions