On Sep 20, 2016 10:52 AM, "Guido van Rossum" <gvanros...@gmail.com> wrote: > > On Tue, Sep 20, 2016 at 8:29 AM, אלעזר <elaz...@gmail.com> wrote: >> *snip* >> The alternative to partial is writing a closure in the form of a function, that needs to be carefully inspected to verify that it is indeed just a partial application and not something more complex. It has more opportunity for introducing an error. And it's longer and adds distance between related parts of the code. > > > We seem to have fundamentally different ideas of what sort of code is most readable. The alternative to partial is usually a lambda, and the signature of the lambda helps me understand how it is being called. I don't see how the lambda is longer or creates more distance. There are some exceptions, when the function has a complex signature that should mostly be preserved (and a few other, rare exceptions). But most of the uses of partial that I found had exactly one call site and the call site was not calling a complex signature. > > A big problem I have reading code that uses partial is that *unless I already know the function being partialed*, the partial() call itself gives me no clue about the signature of that function. So then I have to look for the call site of the partial (what do you call that?) and then in my head I have to combine that with the partial parameters and figure out what is really happening. A lambda would have given me a simple stepping stone. In effect it's a little bit of "typing" right there, showing me the signature that's being called, which is useful for reading the code quickly.
Most often, when I see lambdas used for this, it looks like: lambda *args, **kw: myfunc(partial_arg, *args, **kw) which isn't more readable than just: partial(myfunc, partial_func) Doing something like: lambda x, y: myfunc(partial_arg, x, y) is more error-prone to changes in myfunc's signature. Also, I don't quite understand the readability issue here; all partial is doing is just...err...partializing the function (I should totally patent that phrase). I find it easy to mentally expand it: partial(f, ...) == lambda *args, **kw: f(..., *args, **kw) > Also, I once timed it and could not show that partial was faster. This surprised me but it wa what I measured (in one particular case). > >> >> Elazar >> >> >> בתאריך יום ג׳, 20 בספט' 2016, 18:20, מאת Guido van Rossum < gvanros...@gmail.com>: >>> >>> I am radically opposed to this proposal. Every time I see a partial application I wonder endlessly about what's going on. >>> >>> --Guido (mobile) >>> >>> _______________________________________________ >>> Python-ideas mailing list >>> Python-ideas@python.org >>> https://mail.python.org/mailman/listinfo/python-ideas >>> Code of Conduct: http://python.org/psf/codeofconduct/ > > > > > -- > --Guido van Rossum (python.org/~guido) > > _______________________________________________ > Python-ideas mailing list > Python-ideas@python.org > https://mail.python.org/mailman/listinfo/python-ideas > Code of Conduct: http://python.org/psf/codeofconduct/ -- Ryan [ERROR]: Your autotools build scripts are 200 lines longer than your program. Something’s wrong. http://kirbyfan64.github.io/
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