The documentation for wrapt mentions: Decorators With Optional Arguments <https://wrapt.readthedocs.io/en/latest/decorators.html#decorators-with-optional-arguments>
Although opinion can be mixed about whether the pattern is a good one, if the decorator arguments all have default values, it is also possible to implement decorators which have optional arguments. As Graham hints in his docs, I think repurposing decorator factories as decorators is an antipattern. Explicit is better than implicit. While I *do* understands that what decotools and makefun do are technically independent, I'm not sure I ever want them independently in practice. I did write the book _Functional Programming in Python_, so I'm not entirely unfamiliar with function wrappers. On Tue, Mar 12, 2019, 10:18 AM David Mertz <me...@gnosis.cx> wrote: > The wrapt module I linked to (not funtools.wraps) provides all the > capabilities you mention since 2013. It allows mixed use of decorators as > decorator factories. It has a flat style. > > There are some minor API difference between your libraries and wrapt, but > the concept is very similar. Since yours is something new, I imagine you > perceive some win over what wrapt does. > > On Tue, Mar 12, 2019, 9:52 AM Sylvain MARIE <sylvain.ma...@se.com> wrote: > >> David, Steven, >> >> Thanks for your interest ! >> >> As you probably know, decorators and function wrappers are *completely >> different concepts*. A decorator can directly return the decorated function >> (or class), it does not have to return a wrapper. Even more, it can >> entirely replace the decorated item with something else (not even a >> function or class!). Try it: it is possible to write a decorator to replace >> a function with an integer, even though it is probably not quite useful :) >> >> `decopatch` helps you write decorators, whatever they are. It "just" >> solves the annoying issue of having to handle the no-parenthesis and >> with-parenthesis calls. In addition as a 'goodie', it proposes two >> development styles: *nested* (you have to return a function) and *flat* >> (you directly write what will happen when the decorator is applied to >> something). >> -- >> Now about creating signature-preserving function wrappers (in a >> decorator, or outside a decorator - again, that's not related). That use >> case is supposed to be covered by functools.wrapt. Unfortunately as >> explained here >> https://stackoverflow.com/questions/308999/what-does-functools-wraps-do/55102697#55102697 >> this is not the case because with functools.wrapt: >> - the wrapper code will execute even when the provided arguments are >> invalid. >> - the wrapper code cannot easily access an argument using its name, from >> the received *args, **kwargs. Indeed one would have to handle all cases >> (positional, keyword, default) and therefore to use something like >> Signature.bind(). >> >> For this reason I proposed a replacement in `makefun`: >> https://smarie.github.io/python-makefun/#signature-preserving-function-wrappers >> -- >> Now bridging the gap. Of course a very interesting use cases for >> decorators is to create decorators that create a signature-preserving >> wrapper. It is possible to combine decopatch and makefun for this: >> https://smarie.github.io/python-decopatch/#3-creating-function-wrappers . >> Decopatch even proposes a "double-flat" development style where you >> directly write the wrapper body, as explained in the doc. >> >> Did I answer your questions ? >> Thanks again for the quick feedback ! >> Best, >> >> Sylvain >> >> -----Message d'origine----- >> De : Python-ideas <python-ideas-bounces+sylvain.marie=se....@python.org> >> De la part de Steven D'Aprano >> Envoyé : mardi 12 mars 2019 12:30 >> À : python-ideas@python.org >> Objet : Re: [Python-ideas] Problems (and solutions?) in writing decorators >> >> [External email: Use caution with links and attachments] >> >> ________________________________ >> >> >> >> On Tue, Mar 12, 2019 at 09:36:41AM +0000, Sylvain MARIE via Python-ideas >> wrote: >> >> > I therefore proposed >> > https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fsma >> > rie.github.io%2Fpython-makefun%2F&data=02%7C01%7Csylvain.marie%40s >> > e.com%7C579232e7e10e475314c708d6a6de9d23%7C6e51e1adc54b4b39b5980ffe9ae >> > 68fef%7C0%7C0%7C636879872385158085&sdata=nB9p9V%2BJ7gk%2Fsc%2BA5%2 >> > Fekk35bnYGvmEFJyCXaLDyLm9I%3D&reserved=0 . In particular it >> > provides an equivalent of `@functools.wraps` that is truly >> > signature-preserving >> >> Tell us more about that please. I'm very interested in getting decorators >> preserve the original signature. >> >> >> -- >> Steven >> _______________________________________________ >> Python-ideas mailing list >> Python-ideas@python.org >> >> https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fmail.python.org%2Fmailman%2Flistinfo%2Fpython-ideas&data=02%7C01%7Csylvain.marie%40se.com%7C579232e7e10e475314c708d6a6de9d23%7C6e51e1adc54b4b39b5980ffe9ae68fef%7C0%7C0%7C636879872385158085&sdata=XcYfEginmDF7kIpGGA0XxDZKpUn9e4p2zPFk7UAruYg%3D&reserved=0 >> Code of Conduct: >> https://emea01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fpython.org%2Fpsf%2Fcodeofconduct%2F&data=02%7C01%7Csylvain.marie%40se.com%7C579232e7e10e475314c708d6a6de9d23%7C6e51e1adc54b4b39b5980ffe9ae68fef%7C0%7C0%7C636879872385158085&sdata=20ZrtVQZbpQ54c96veSXIOfEK7rKy0ggj0omTZg3ri8%3D&reserved=0 >> >> ______________________________________________________________________ >> This email has been scanned by the Symantec Email Security.cloud service. >> ______________________________________________________________________ >> >
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