Latest #metaprogramming Threads 
Imagine a conductor forced to relearn musical notation every time a new instrument joins the orchestra. Violin—one system of writing. Cel...
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I’ve been heavily working with macros for more than 10 years already and I always used kinda ad-hoc code to expand/debug/test those when ...
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In Phoenix apps, the web module provides this “re-dispatch into methods” technique for use (see __using__):
defmodule ExampleWeb.Router ...
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I saw this LinkedIn post:
*Can your programming language do this?
This is a macro in Clojure called `dotrace`. When you surround a pie...
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What’s the type to use for a function that returns a quote?
For example:
@spec f() :: what_goes_here
def f() do
quote do
code
e...
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Hello, so I was wondering if something like newtypes is possible in Elixir and found something that does it but I THINK (correct me if I’...
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I have a module for which I want to create a function rule_ids/0 at compile time. The code collects the rule ids at compile time from the...
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I have a problem, where i have a macro the calls another function. I want to be able to add optional guards to my macro, and call the nes...
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Warning: Calling this function inside a macro is considered bad practice as it will attempt to evaluate runtime values at compile time. M...
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In file 1:
defmodule Utils.Struct do
# this is for importing definitions when "use Utils.Struct" is called
defmacro __using__(_opts...
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Hi there,
After reading @ericmj response here (Using unquote outside of quote block - #6 by ericmj) about “unquote fragments”, I still c...
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Hello,
I just extracted the boilerplate management code that I used to work with in previous years:
It is yet another generic input d...
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I saw this LinkedIn post:
*Can your programming language do this?
This is a macro in Clojure called `dotrace`. When you surround a pie...
New
I’ve been heavily working with macros for more than 10 years already and I always used kinda ad-hoc code to expand/debug/test those when ...
New
Imagine a conductor forced to relearn musical notation every time a new instrument joins the orchestra. Violin—one system of writing. Cel...
New
In Phoenix apps, the web module provides this “re-dispatch into methods” technique for use (see __using__):
defmodule ExampleWeb.Router ...
New
Last Three Year's Trending
I can’t seem to pass an anonymous function as an option to a Plug. I am using plug_hmouse which from the documentation takes an option di...
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Can Elixir code detect whether it is executing at compile time? I would like to write something like the following macro:
defmacro foo()...
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I know this has been asked before, but I still can’t get it to work. I have code like this…
def case_stmt(input) do
[c1, c2, c3, c4] =...
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Note: There are a few folks I’d really love to hear from, time permitting. Pinging in case the title isn’t catchy enough :slight_smile: @...
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I would like to add a function to my project that is available throughout all modules without aliasing/importing it. How should I go abou...
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I’m trying to build a protocol and a test suite to implement different adapters (impls of the protocol).
I tried to use a CaseTemplate, ...
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I am trying to hook into the @doc deprecated: "message" annotation using __on_definition__.
defmodule ExampleCompiler do
def __on_defi...
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After reading Metaprogramming Elixir, and the hexdocs on metaprogramming and macros, I was wondering how this ties into macros we use eve...
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I’m developing a Supabase client for Elixir with complete support for all their services, like:
storage
auth
realtime
UI (live view)
S...
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I’m doing some questionable meta-programming, and could use your help!
I’m using Macro.prewalk to traverse some source code, with the go...
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I have a module utils,which is supposed to be used by MOdule A, B,C,D… and so on. The issue is utils modules have lot of constants, const...
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I’m not very used to macros/compile time manipulation, but I will explain what I want to achieve and would like to know if it’s possible ...
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I have a system that has thousands of run-time generated modules, some of which I want to cache for future reloading.
Ordinarily, the BE...
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With the following code:
defmodule Foobar do
defmacro b(arg) do
arg
|> String.split("\n")
|> IO.inspect()
end
d...
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I’m in the process of creating some reusable test modules using a macro:
defmodule SharedTestCase do
defmacro define_tests(do: block) ...
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Trending Over Three Years
Hi there,
How I can build queries with dynamic fields assignment in Ecto?
I try to do next thing:
import Ecto.Query
field = :id
value ...
New
Hi,
I have been coding with Elixir for 9+ months and I encountered several time the concept of quotes and each time, I think “ok, today ...
New
I have a bunch of functions in a module, that I’d like to dynamically add to a __using__ macro:
defmodule A do
defmacro __using__(_opt...
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I’m improving some documentation in Elixir, and in order to do so, I need to dynamically build a list of atoms, but without using string...
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parameterized pipe in elixir: |n>
edit: negative index in |n> and mixed usage with |> are supported
example:
use ParamPipe
...
New
Hi community!
What is the correct way to implement the __using__ macro with an option that changes the way generated functions behave? O...
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Hi everyone, I was toying around with macros today and I reached a stagnation point. After trying multiple approaches I started to think ...
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I’m trying to do something similar to wath ecto does when defining schemas. Basically the idea is:
defmodule Test do
use TableBuilder
...
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I have three identical methods in my module, that do (almost) exactly the same thing. Instead of repeating the function definitions, I am...
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Elixir newbie here working on a stemmer for a document indexing engine. The stemming algorithm has dozens of steps with many tests per s...
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I’m struggling with overriding hygiene during manual manipulation of AST with Macro.postwalk. In short, I want to provide a syntax for in...
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I want to programmatically generate input objects from introspecting my schema, but I can’t figure out the metaprogramming to do so.
Ess...
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Hi all,
I’ve been playing with Specify lately and I’m trying to get the @type module attribute like the @doc one, so as to link to that ...
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defmodule Bar do
@after_compile __MODULE__
defmacro __before_compile__(_env) do
IO.inspect("#{__MODULE__}.__before_compile__")
...
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Easiest to ask this in code…
defmodule Foo do
use Tagger
tag(:red)
end
defmodule Bar do
use Tagger
tag(:blue)
end
Then at runt...
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