[Doc-SIG] Proposal: don't nest optional brackets

[Georg Brandl]

A.M. Kuchling schrieb:
> To show a series of optional parameters, currently we nest square
> brackets.
> 
> http://docs.python.org/dev/library/warnings.html#warnings.filterwarnings
> 
> warnings.filterwarnings(action[, message[, category[, module[,
> lineno[, append]]]]])
> 
> My proposal is that we drop the nesting and write this as:
> 
> warnings.filterwarnings(action [, message, category, module, lineno, append])
> 
> Currently the stylesheets make the brackets very big and dark, so I've
> also added a space before the bracket.

Which will be ignored by the signature parser :)

> This change means we'd lose the ability to show when two optional
> arguments must be supplied at the same time, which could currently be
> written like this:
> 
> warnings.filterwarnings(action[, message, category[, module]])
> 
> In this hypothetical example, if you supply 'message' you must also
> supply 'category'.  But I think that for most functions, you can
> supply each optional argument or not; you rarely need to supply two
> optional arguments that are tied in this way, and we can handle such
> cases by adding a sentence such as "Both message and category parameters 
> must be supplied."  

That's reasonable. I can't remember if there's a function like this
anywhere (with only the signature as a sign of this calling requirement).

> A few places (difflib, doctest, probably others) use this format:
> 
> ... function:: context_diff(a, b[, fromfile][, tofile][, fromfiledate][, tofiledate][, n][, lineterm])
> 
> It's better than the nested version -- at least it avoids the ]]]]])
> at the end -- but I think having a single set of square brackets also
> works and reduces the symbolic noise further.
> 
> ... function:: context_diff(a, b [, fromfile, tofile, fromfiledate, tofiledate, n, lineterm])
> 
> The brackets are large enough that I think this would still be quite
> readable; it doesn't seem likely that readers will miss that these
> parameters are optional.
> 
> What does everyone think?

I'm +0. I'd like to hear Fred's opinion since (I guess) he introduced the
nested bracket notation. If he's okay with it, I'll write a script that
converts the signatures in the whole documentation.

cheers,
Georg

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