[Python-ideas] Syntax idea: escaping names to avoid keyword ambiguity

Carl Smith carl.input at gmail.com
Mon May 14 17:06:57 EDT 2018

Just to be clear, if `foo` was introduced as a new infix operator, projects
that used `foo`
as a name would not be able to also use `foo` as an infix operator in the
file that defines
`foo` as a name, but could use the operator throughout the rest of their

-- Carl Smith
carl.input at gmail.com

On 14 May 2018 at 21:52, Carl Smith <carl.input at gmail.com> wrote:

> I can only think of three ways to reference a name defined in a different
> file: In an import
> statement, as properties of objects and as keyword arguments.
> Import statements are implicit assignments, so if Python allowed the
> following grammar,
> you could still import the odd thing that had a reserved name, without
> bringing that name
> into your local namespace.
>     from <keyword> import <keyword> as <name>
> Property names always follow a dot, where only a name is valid, so Python
> could allow
> this too:
>     <expression>.<keyword>
> Keyword arguments are also generally unambiguous, as they have to appear
> within the
> parens of an invocation, before the equals sign:
>     <expression>(<keyword>=<expression>)
> If Python allowed those three examples (but still prevented users from
> *defining* names
> that are keywords) new keywords could be introduced without breaking old
> code , and the
> language would only require relatively minor tweaking.
> -- Carl Smith
> carl.input at gmail.com
> On 14 May 2018 at 19:11, Terry Reedy <tjreedy at udel.edu> wrote:
>> On 5/14/2018 10:02 AM, Clint Hepner wrote:
>>> On 2018 May 14 , at 6:47 a, Daniel Moisset <dmoisset at machinalis.com>
>>>> wrote:
>>>> Following up some of the discussions about the problems of adding
>>>> keywords and Guido's proposal of making tokenization context-dependent, I
>>>> wanted to propose an alternate way to go around the problem.
>>> My main objection to what follows is that it doesn't seem to offer any
>>> benefit over the current practice of appending an underscore (_) to a
>>> keyword to make it a valid identifier.
>> Tkinter uses this convention for a few option names that clash.
>> --
>> Terry Jan Reedy
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