Python object type judgment and function overloading

1. Determine the object type

You can know the type of the object through the type function. The sample code is as follows:

x = 'Hello'
s = type(x)
print s
x = 'Hello'
s = type(x)
print s

2. Function overloading

When writing functions, we often encounter the need to deal with different parameter types and case of different number of parameters.

In C++, multiple functions with the same name but different parameters are usually defined to achieve overloading.

But overloading in Python can be achieved by another method: parameter type judgment + default value

import os, sys
def tracelog(s='', n=40):
    if isinstance(n, int):
        print '-'*n
    else:
        print '-'*40
    if isinstance(s, str):
        print s
    elif isinstance(s, list):
        s1 = ''
        for x in s:
            s1 = s1 + ' ' + x
        print s1
   
def main():
    tracelog(n=50)
    tracelog(sys.argv)
    tracelog(n=20)

​​​

main( )

import os, sys
  
def tracelog(s='', n=40):
    if isinstance(n, int):
        print '-'*n
    else:
        print '-'*40
    if isinstance(s, str):
        print s
    elif isinstance(s, list):
        s1 = ''
        for x in s:
            s1 = s1 + ' ' + x
        print s1
  
def main():
    tracelog(n=50)
    tracelog(sys.argv)
    tracelog(n=20)
main()

The above code defines a function tracelog. This function will print out the s parameter. The s parameter can be a string or a list, and it can also print a horizontal line of a specified length

Among them: isinstance function It is a function used to determine whether an object is of a specific type. The second parameter is the object type, which can be queried through the type function.