On Fri, Jul 27, 2012 at 8:07 AM, Rob Ashton <[email protected]> wrote: > Do we need dependency injection in nodejs? Well - if you mean dependency > injection literally, we have it already, it looks like this > > function doSomething(dependency) { > > } > > doSomething(new FooDependency()) > > or > > doSomething(new BarDependency()) > > or > > var Animal = function(vocals) { > this.vocals = vocals > } > > var cat = new Animal(miaow) > cat dog = new Animal(woof) > > etc > > ---------- > > If you're talking about 'container' support to support this, it's a road > that has been trodden well by .NET and Java devs, and has been shown time > and time again to lead full circle to the very beginning where you just > build your object graphs manually and introduce extensibility points where > you need them for either mocking out slow dependencies for testing or > allowing consumers to control something about your code. > > Trying to bake in support to this as part of the require system seems like > asking for trouble, keep it explicit, keep it as needed and let the goodness > follow.
I agree with this. If you need dependency injection, design it into your system. Don't force it on unsuspecting modules. A couple of things that come to mind off the top of my head: * If I compel some module to use, say, 'my-funky-fs' instead of 'fs' without knowing it, will that cause *its* dependencies to have their usage of 'fs' replaced too? What if one of them was already replacing it with something of its own choosing, perhaps using a different mechanism (like maybe graceful-fs)? * If someone reports an issue with one of my packages, and I spend a bunch of my time debugging it, only to discover that the reporter replaced one of my dependencies with some other flaky substitute and that's the culprit, I'm not going to be happy about that. I design my packages to work with their declared dependencies, or I specifically design for dependency injection if it's needed. > My two cents. And mine. :) -- Martin Cooper > On Fri, Jul 27, 2012 at 4:45 PM, Eldar <[email protected]> wrote: >> >> Do we need this in Node? >> >> My answer is yes we need some (simple) way to specify the app level >> dependencies at runtime. Here is my take on this. Please checkout and let >> me know how do you feel about. >> >> But the idea is very simple: >> >> >> // inside any index.js >> var R = require('runtime').patchNative() >> var use = R(module).use >> >> use('fs', 'node_modules/third/party', require('./smart-fs')) >> >> That's it. Third party module just uses our smart file system >> >> -- >> Job Board: http://jobs.nodejs.org/ >> Posting guidelines: >> https://github.com/joyent/node/wiki/Mailing-List-Posting-Guidelines >> You received this message because you are subscribed to the Google >> Groups "nodejs" group. >> To post to this group, send email to [email protected] >> To unsubscribe from this group, send email to >> [email protected] >> For more options, visit this group at >> http://groups.google.com/group/nodejs?hl=en?hl=en > > > -- > Job Board: http://jobs.nodejs.org/ > Posting guidelines: > https://github.com/joyent/node/wiki/Mailing-List-Posting-Guidelines > You received this message because you are subscribed to the Google > Groups "nodejs" group. > To post to this group, send email to [email protected] > To unsubscribe from this group, send email to > [email protected] > For more options, visit this group at > http://groups.google.com/group/nodejs?hl=en?hl=en -- Job Board: http://jobs.nodejs.org/ Posting guidelines: https://github.com/joyent/node/wiki/Mailing-List-Posting-Guidelines You received this message because you are subscribed to the Google Groups "nodejs" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/nodejs?hl=en?hl=en
