4 ms·

I'm familiar with dry-rb coding style and I think it is very difficult to reason about. Metaprogramming often feels like magic but it comes at a price - hard fo

I'm familiar with dry-rb coding style and I think it is very difficult to reason about. Metaprogramming often feels like magic but it comes at a price - hard for newbies to grok and impossible for static tools to work with. I would only advise using it (if at all) in well-tested libraries that expose a well-documented public API.

pducks32 9y ago
It is hard to reason about. I think if you understood it (meaning you are a core contributor) then you feel like it really helps organize your code and keep everything reasonable. But to a newbie it is the exact opposite. I know in my projects I use some techniques which if you continued to work on the project you would really appreciate how many problems it solves but it seems crazy to my coworkers. Luckily it's a small gem and I'm the one who works on it but still.
rhizome 9y ago
Things like "super.tap" make me think I'm about to go on a wild goose chase.
- dperfect 9y ago
  It's pretty simple and useful; instead of def my_method super_result = super ... (do something with super_result, or simply after super has been called) ... super_result <== to make sure your method returns the result of super end you can just do this: def my_method super.tap{|result| (do something with/after result) } <== will still return the result of super end
  - kkirsche 9y ago
    Tap is by far my favorite method though usually on hashes to add conditionals
  - rhizome 9y ago
    I know what it does, but isn't it (and your examples) an instance of the Call Super[1] antipattern? 1. https://www.martinfowler.com/bliki/CallSuper.html https://www.martinfowler.com/bliki/CallSuper.html
    - dperfect 9y ago
      From my understanding, the anti-pattern is related to creating an API that requires a call to super when overriding a method. super.tap may be used when interacting with an API that employs the "call super" anti-pattern, but calling super is not itself an instance of the anti-pattern; it can be used in perfectly legitimate cases as well.
ooqr 9y ago
The problem as I see it is when metaprogramming is used laterally or vertically. If code at a higher scope changes code at a lower scope, this makes a lot more sense than the arbitrary and profane directions of mutability that Ruby allows. So, like all things in Ruby, it's a matter of how the tool is used. To metaprogramming! The cause of -- and solution to -- all of life's problems.
mtkd 9y ago
it's a tool in the toolbox - just occasionally it can give a really elegant solution to something that would otherwise be spaghetti like many other features on the fringe of a language it's important to understand when it's appropriate to use also - there are few better buzzes writing code than doing something neat, skinny and appropriate with those Ruby features
ashark 9y ago
I'm immediately put off by any system that doesn't let me figure out WTF something actually is until runtime. I should be able to learn most of what I need to know about a codebase with a basic text editor and grep. Some questions should be for documentation to answer, but "what the hell is this variable representing?" isn't one of them. I prefer to let my code and my tools remember stuff for me. Rails and similarly-magical Ruby systems have too high a (human) memory overhead for my taste. Hard to jump in and out of if it's not the main thing you do every day.
- ooqr 9y ago
  I think Rails does a pretty good job of making well-documented sense. Lots of crappy gems abuse things like implicit global variables, rewriting core methods, and other monstrous applications of metaprogramming.
lacampbell 9y ago
I would only advise using it (if at all) in well-tested libraries that expose a well-documented public API. I sometimes fantasise about a world where what you describe is just... how we write software. I really wish i could use my colleagues libraries instead of digging into their source code.
6t6t6t6 9y ago
Metaprogramming in Rails is for infrastructure code, not business logic. As far as the metaprogramming is encapsulated in a module with a good API and serves to make business code easier to read, it can be extremely helpful.

pducks32 9y ago

It is hard to reason about. I think if you understood it (meaning you are a core contributor) then you feel like it really helps organize your code and keep everything reasonable. But to a newbie it is the exact opposite. I know in my projects I use some techniques which if you continued to work on the project you would really appreciate how many problems it solves but it seems crazy to my coworkers. Luckily it's a small gem and I'm the one who works on it but still.

rhizome 9y ago

Things like "super.tap" make me think I'm about to go on a wild goose chase.

dperfect 9y ago
It's pretty simple and useful; instead of def my_method super_result = super ... (do something with super_result, or simply after super has been called) ... super_result <== to make sure your method returns the result of super end you can just do this: def my_method super.tap{|result| (do something with/after result) } <== will still return the result of super end
- kkirsche 9y ago
  Tap is by far my favorite method though usually on hashes to add conditionals
- rhizome 9y ago
  I know what it does, but isn't it (and your examples) an instance of the Call Super[1] antipattern? 1. https://www.martinfowler.com/bliki/CallSuper.html https://www.martinfowler.com/bliki/CallSuper.html
  - dperfect 9y ago
    From my understanding, the anti-pattern is related to creating an API that requires a call to super when overriding a method. super.tap may be used when interacting with an API that employs the "call super" anti-pattern, but calling super is not itself an instance of the anti-pattern; it can be used in perfectly legitimate cases as well.

ooqr 9y ago

The problem as I see it is when metaprogramming is used laterally or vertically. If code at a higher scope changes code at a lower scope, this makes a lot more sense than the arbitrary and profane directions of mutability that Ruby allows. So, like all things in Ruby, it's a matter of how the tool is used. To metaprogramming! The cause of -- and solution to -- all of life's problems.

mtkd 9y ago

it's a tool in the toolbox - just occasionally it can give a really elegant solution to something that would otherwise be spaghetti like many other features on the fringe of a language it's important to understand when it's appropriate to use also - there are few better buzzes writing code than doing something neat, skinny and appropriate with those Ruby features

ashark 9y ago

I'm immediately put off by any system that doesn't let me figure out WTF something actually is until runtime. I should be able to learn most of what I need to know about a codebase with a basic text editor and grep. Some questions should be for documentation to answer, but "what the hell is this variable representing?" isn't one of them. I prefer to let my code and my tools remember stuff for me. Rails and similarly-magical Ruby systems have too high a (human) memory overhead for my taste. Hard to jump in and out of if it's not the main thing you do every day.

ooqr 9y ago
I think Rails does a pretty good job of making well-documented sense. Lots of crappy gems abuse things like implicit global variables, rewriting core methods, and other monstrous applications of metaprogramming.

lacampbell 9y ago

I would only advise using it (if at all) in well-tested libraries that expose a well-documented public API. I sometimes fantasise about a world where what you describe is just... how we write software. I really wish i could use my colleagues libraries instead of digging into their source code.

6t6t6t6 9y ago

Metaprogramming in Rails is for infrastructure code, not business logic. As far as the metaprogramming is encapsulated in a module with a good API and serves to make business code easier to read, it can be extremely helpful.