I know it can be overwhelming but I really think it would behoove you to thoroughly read all of the application, guides, and regional guides completely.
"You must select the visa office that serves your country of nationality or the country where you have been legally admitted for at least one year."
http://www.cic.gc.ca/english/information/offices/apply-where.asp You will note if you scroll to Tunisia it says Paris. ( one does not have to live in FRANCE, as noted in the link in my first response, This office processes immigrant application for all of the following places Algeria, Andorra, Azores, Belgium, Canary Islands, France, Gibraltar, Libya, Liechtenstein, Luxembourg, Madeira, Monaco, Portugal, Spain, Switzerland, Tunisia)
On the Canadian Embassy in Tunisia it says "
*Immigrant applications are not accepted in Tunisia. Please visit the website of our Visa Section in Paris"
http://www.canadainternational.gc.ca/tunisia-tunisie/visas/index.aspx?menu_id=2&view=dIf the applicant has been legally admitted to Italy for a period of a year then the applicant can apply through the ROME visa office. (Rome also handles Albania, Greece, Italy, Malta, San Marino, Vatican City)
The choice is the applicants, you may want to look at times for both offices. In either case one will need to use the regional guide for Africa.