How to create a Python function which accepts multiple input arguments

Written by - 0 comments

Published on - Listed in Coding Python


While I was working on a Python script, I wanted to create a function which should print additional (verbose) output for debugging purposes.

Python coding

TypeError: function() takes 1 positional argument but N were given

To do this, I created a function "verboseoutput" which is then called later in the script (while parsing JSON data):

[...]

# Verbose output for debugging help
def verboseoutput(message) :
    print(time.strftime("%Y%m%d %H:%M:%S"), message)



# handle json input
with open('tests/input.json', 'r') as json_file:
    data = json.load(json_file)

    for item in data:
        verboseoutput("Found elements:", item['Status'], item['Name'], item['Id'])

[...]

However when the Python script was executed, the following error message showed up:

ck@linux ~ $ python3 script.py
Traceback (most recent call last):
  File "/home/ck/script.py", line 93, in <module>
    verboseoutput("Found elements:", item['Status'], item['Name'], item['Id'])
TypeError: verboseoutput() takes 1 positional argument but 4 were given

The error hints that my verboseoutput() function only supports one (1) argument, but 4 were submitted to the function:

  1. "Found elements:" (string)
  2. item['Status'] (value from the parsed JSON data)
  3. item['Name'] (value from the parsed JSON data)
  4. item['Id'] (value from the parsed JSON data)

One solution would be to adjust the verboseoutput function and enter the exact amount of arguments:

# Verbose output for debugging help
def verboseoutput(arg1, arg2, arg3, arg4) :
    print(time.strftime("%Y%m%d %H:%M:%S"), message)

However this only works if the number of arguments always remain the same number.

Allow the function to accept variable number of arguments

As you can imagine, a verbose message could just be a single string - or could contain a list of variables. This function should therefore be flexible to accept anything it's been thrown at.

This can be done by setting the function to accept a variable number of arguments:

[...]

# Verbose output for debugging help
def verboseoutput(*message) :
    print(time.strftime("%Y%m%d %H:%M:%S"), message)

# handle json input
with open('tests/input.json', 'r') as json_file:
    data = json.load(json_file)

    for item in data:
        verboseoutput("Found elements:", item['Status'], item['Name'], item['Id'])

[...]

Noticed the asterisk in front of the input argument (*message)? This tells the function to accept a variable number of arguments as input.

After this change, the Python script is executed again and the verbose output is shown as expected:

ck@linux ~ $ python3 script.py
20240215 15:24:03 ('Found elements:', {'HealthRollup': 'OK', 'State': 'Enabled'}, 'HPE MR416i-o Gen11', 'DE00E000')
20240215 15:24:03 ('Found elements:', {'HealthRollup': 'OK', 'State': 'Enabled'}, 'HPE NS204i-u Gen11 Boot Controller', 'DE00B000')
20240215 15:24:03 ('Found elements:', {'HealthRollup': 'OK', 'State': 'Enabled'}, 'HPE NS204i-u Gen11 Boot Controller', 'DE00B000')



Add a comment

Show form to leave a comment

Comments (newest first)

No comments yet.

RSS feed

Blog Tags:

  AWS   Android   Ansible   Apache   Apple   Atlassian   BSD   Backup   Bash   Bluecoat   CMS   Chef   Cloud   Coding   Consul   Containers   CouchDB   DB   DNS   Database   Databases   Docker   ELK   Elasticsearch   Filebeat   FreeBSD   Galera   Git   GlusterFS   Grafana   Graphics   HAProxy   HTML   Hacks   Hardware   Icinga   Influx   Internet   Java   KVM   Kibana   Kodi   Kubernetes   LVM   LXC   Linux   Logstash   Mac   Macintosh   Mail   MariaDB   Minio   MongoDB   Monitoring   Multimedia   MySQL   NFS   Nagios   Network   Nginx   OSSEC   OTRS   Office   PGSQL   PHP   Perl   Personal   PostgreSQL   Postgres   PowerDNS   Proxmox   Proxy   Python   Rancher   Rant   Redis   Roundcube   SSL   Samba   Seafile   Security   Shell   SmartOS   Solaris   Surveillance   Systemd   TLS   Tomcat   Ubuntu   Unix   VMWare   VMware   Varnish   Virtualization   Windows   Wireless   Wordpress   Wyse   ZFS   Zoneminder