[Python-ideas] textFromMap(seq , map=None , sep='' , ldelim='', rdelim='') (original) (raw)

Boris Borcic bborcic at gmail.com
Tue Oct 26 16:32:10 CEST 2010

Nick Coghlan wrote:

With the str method, while some people may find it odd to have the method invocation on the separator, they typically don't forget the order once they learn it for the first time.

OTOH, it is a pain that join and split aren't both methods on the separator. Imho, 71% of what makes it strange for join to be a method on the separator, is that split doesn't follow the same convention. But split only makes sense for strings, not arbitrary sequences. It's the other way around for join.

I don't feel your "the other way around" makes clear sense. The /split/ function depends on two string parameters, what allows a design choice on which one should be the object when making it a method call. I have been burned more than once with internalizing that /join/ is a method on the separator, just to (re-)discover that such is not the case of the converse method /split/ - although it could (and therefore should, to minimize cognitive dissonance).

IOW, instead of whining that there is no way to make join a method on what "we should" think of as the prominent object (ie the sequence/iterator) and then half-heartedly promote sep.join as the solution, let's take the sep.join idiom seriously together with its implication that a core object role for a string, is to act as a separator.

And let's then propagate that notion, to a coherent definition of split that makes it as well a method on the separator.

Cheers, BB

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