Question

I want to understand why the below code throws an error, I am trying to delete an item in a dictionary if a specific key is present.

    >>> 
    >>> a = {1:1, 2:2}
    >>> type(a)
    <type 'dict'>
    >>> a.has_key(1) and del a[1]
    File "<stdin>", line 1
    a.has_key(1) and del a[1]
                   ^
    SyntaxError: invalid syntax
    >>> 

The only way to make the above code work is to use

    if a.has_key(1): del a[1]

Answer 1

del is a statement. You can’t use it as part of an expression. It’s not clear what you’re trying to do with a.has_key(1) and del a[1] anyway. Perhaps you mean:

if a.has_key(1):
    del a[1]

Or the alternative a.pop(1, None) which will also remove the 1 key from the dict.