[Python-Dev] [Python-ideas] Proposed addtion to urllib.parse in 3.1 (and urlparse in 2.7)

Mart Sõmermaa mrts.pydev at gmail.com
Sat Apr 18 22:42:40 CEST 2009

On Sat, Apr 18, 2009 at 3:41 PM, Nick Coghlan <ncoghlan at gmail.com> wrote:
> Yep - Guido has pointed out in a few different API design discussions
> that a boolean flag that is almost always set to a literal True or False
> is a good sign that there are two functions involved rather than just
> one. There are exceptions to that guideline (e.g. the reverse argument
> for sorted and list.sort), but they aren't common, and even when they do
> crop up, making them keyword-only arguments is strongly recommended.

As you yourself previously noted -- "it is often
better to use *args for the two positional arguments - it avoids
accidental name conflicts between the positional arguments and arbitrary
keyword arguments" -- kwargs may cause name conflicts.

But I also agree, that the current proliferation of positional args is ugly.

add_query_params_no_dups() would be suboptimal though, as there are
currently three different ways to handle the duplicates:
* allow duplicates everywhere (True),
* remove duplicate *values* for the same key (False),
* behave like dict.update -- remove duplicate *keys*, unless
explicitly passed a list (None).

(See the documentation at

Additionally, as proposed by Antoine Pitrou, removing keys could be implemented.

It feels awkward to start a PEP for such a marginal feature, but
clearly a couple of enlightened design decisions are required.

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