Comments on: Gotcha — forgetting parentheses

By: Michael Buckley

Michael Buckley — Sat, 06 Nov 2010 08:23:07 +0000

The first time I stumbled across code like this was in a programming exam paper. I had a little fun with it as the expense of the lecturer after I became a tutor for the subject

By: jesus

jesus — Sun, 03 Oct 2010 19:31:58 +0000

I’m new to python and this gotcha just got me, I spent ages looking for a bug elsewhere in the code because I didn’t know of this feature of python. So I’m just commenting to call olilo an idiot.

By: Nathon

Nathon — Wed, 07 Apr 2010 17:53:42 +0000

The reason this is a gotcha is that it can bite newbie programmers or programmers unfamiliar with Python. Obviously it’s an important language feature that functions and methods can be passed around as arguments and stored in collections. However, someone new to Python and the concept of functions as first class citizens might expect the interpreter to catch the error just like how they would expect Python to alert them if they had passed 12 parameters to a function that only takes 2. They also might actually expect the function to be called, since languages like Ada allow subroutines with zero parameters to be called without parentheses.

By: olilo

olilo — Tue, 17 Mar 2009 14:29:00 +0000

Hi,

Just to tell you that it's not a gotcha at all. The syntax requires you to call a method with parenthesis.

How would you pass a function reference to another method (a callback method, for example) without this 'gotcha' ?

You don't have to be particularly carefull about it. If you want to call the method, you need parenthesis. If you need to use the function object for referencing, you don't add parenthesis.

But calling it a gotcha is strange to me.

PS: beside that, thank you for your website. It's very interesting.

Regards,