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Re: how to use a variable in a plain-file object?
From: |
raingloom |
Subject: |
Re: how to use a variable in a plain-file object? |
Date: |
Thu, 16 May 2024 16:15:21 +0000 |
On 2024-05-16 17:57, Giovanni Biscuolo wrote:
> Hello,
>
> sorry for the very guile-absolute-beginner question, but I'd like to use
> a declared variable in a plain-file object, so I can write something
> like in this pseudo-code snippet:
>
> --8<---------------cut here---------------start------------->8---
>
> (define variable1 "var1-value")
> (define variable2 "var2-value")
>
> [...]
>
> (define %my-file-object
> ,(plain-file "something.conf" "
> # This is an example configuration file
>
> attribute1 =" variable1 "
>
> attribute2 =" variable2 "
>
> "))
>
> --8<---------------cut here---------------end--------------->8---
>
> and obtain a "something.conf" file like this:
>
> --8<---------------cut here---------------start------------->8---
> # This is an example configuration file
>
> attribute1 = var1-value
>
> attribute2 = var2-value
>
> --8<---------------cut here---------------end--------------->8---
>
> how can I do, please?
>
> Thanks, Gio'
You probably want a G-expression.
Short untested example:
(define name "Giovanni")
(define greeting-gexp
#~(begin (with-output-to-file #$output (lambda _ (write (string-append
"Hello, " #$name "!"))))))
You should be able to use greeting-gexp in place of %my-file-object.
I highly recommend reading the relevant docs in Guix's info pages.
Online version:
https://guix.gnu.org/manual/en/html_node/G_002dExpressions.html
Related blog post:
https://guix.gnu.org/en/blog/2023/dissecting-guix-part-3-g-expressions/