Subject: [bug#57963] [PATCH v5 2/2] home: services: Support user's fontconfig configuration.

From: Taiju HIGASHI <[email-masked]>
Date: Wed, 12 Oct 2022 20:38:11 +0900

Andrew Tropin <[email-masked]> writes:

> On 2022-10-11 12:54, Taiju HIGASHI wrote:
>
>> Hi Andrew,
>>
>> Thank you for your review!
>>
>>>> +(define (string-list? value)
>>>> +  (and (pair? value) (every string? value)))
>>>
>>> Better to use list? here and in the other places, at least for the
>>> consistency, but also for semantic meaning.
>>
>> OK. I'll rewrite it to below.
>>
>> --8<---------------cut here---------------start------------->8---
>> (define (string-list? value)
>>   (and (list? value) (every string? value)))
>> --8<---------------cut here---------------end--------------->8---
>>
>>>> +
>>>> +(define (serialize-string-list field-name value)
>>>> +  (sxml->xml-string
>>>> +   (map
>>>> +    (lambda (path) `(dir ,path))
>>>> +    (if (member guix-home-font-dir value)
>>>> +        value
>>>> +        (append (list guix-home-font-dir) value)))))
>>>> +
>>>> +(define (serialize-string field-name value)
>>>> +  (define (serialize type value)
>>>> +    (sxml->xml-string
>>>> +     `(alias
>>>> +       (family ,type)
>>>> +       (prefer
>>>> +        (family ,value)))))
>>>> +  (match (list field-name value)
>>>> +    (('default-font-serif-family family)
>>>> +     (serialize 'serif family))
>>>> +    (('default-font-sans-serif-family family)
>>>> +     (serialize 'sans-serif family))
>>>> +    (('default-font-monospace-family family)
>>>> +     (serialize 'monospace family))))
>>>> +
>>>> +(define-maybe string)
>>>> +
>>>> +(define extra-config-list? list?)
>>>> +
>>>> +(define-maybe extra-config-list)
>>>> +
>>>> +(define (serialize-extra-config-list field-name value)
>>>> +  (sxml->xml-string
>>>> +   (map (match-lambda
>>>> +          ((? pair? sxml) sxml)
>>>
>>> Other branches would never be visited because it will fail earlier by
>>> define-configuration predicate check for extra-config-list? (which is
>>> basically list?).
>
> Oh, I missed the map over the list elements and slightly missread the
> code.  I thought (according to my incorrect perception of
> implementation) extra-config have to be either sxml or string, that's is
> why I said that it will fail earlier because plan string value won't
> satisfy list predicate attached to extra-config field, but in a fact
> extra-config is always a list, but can be a list of sxml's and strings
> mixed together.
>
> Thus, some of my comments are invalid.  Sorry for the confusion.  I'll
> rephrase and elaborate in the later message.

I was worried that I was the only one who did not understand the code I
wrote, but I've relieved to hear that it was a misunderstanding :)

Is it OK to have multiple data types (XML string and SXML list) in a
list?

>> We can specify invalid value such as (list "foo" '(foo bar) 123).
>>
>>> Also, making multi-type fields is debatable, but isn't great IMO.
>>
>> I see. If we had to choose one or the other, I would prefer the
>> string-type field.
>>
>>> If serialization would support G-exps, we could write
>>>
>>> (list #~"RAW_XML_HERE")
>>>
>>> or even something like this:
>>>
>>> (list #~(READ-THE-WHOLE-FILE #$(local-file "our-old.xml")))
>>
>> Does it mean that the specification does not allow it now? Or does it
>> mean that it is not possible with my implementation?
>>
>
> It's not possible with the current implementation.

I'll try to modify it so that it can support G-exps.

>>>> + ((? string? xml) (xml->sxml xml)) + (else + (raise
>>>> (formatted-message + (G_ "'extra-config' type must be xml string or
>>>> sxml list, was given: ~a") + value)))) + value))) +
>>>> +(define-configuration home-fontconfig-configuration +
>>>> (font-directories + (string-list (list guix-home-font-dir))
>>>
>>> It's not a generic string-list, but a specific font-directories-list
>>> with extra logic inside.
>>>
>>> Also, because guix-home-font-dir always added to the list, the default
>>> value should '() and field should be called additional-font-directories
>>> instead.  Otherwise it will be confusing, why guix-home-font-dir is not
>>> removed from the final configuration, when this field is set to a
>>> different value.
>>>
>>> I skimmed previous messages, but sorry, if I missed any already
>>> mentioned points.
>>
>> Sure, It is more appropriate that the field type is to
>> font-directories-list field name is to additional-font-directories.
>>
>
> As Liliana mentioned in the other message, it's better not to set
> anything implicitly.  It's better to keep the name, but change the
> implementation and remove implicitly and unconditionally added
> directory.

OK.  I'll modify the default value to an empty list and include
~/.guix-home/profile/share/fonts in the sample code in the
documentation.

>>>> +   "The directory list that provides fonts.")
>>>> +  (default-font-serif-family
>>>> +    maybe-string
>>>> +    "The preffered default fonts of serif.")
>>>> +  (default-font-sans-serif-family
>>>> +    maybe-string
>>>> +    "The preffered default fonts of sans-serif.")
>>>> +  (default-font-monospace-family
>>>> +    maybe-string
>>>> +    "The preffered default fonts of monospace.")
>>>> +  (extra-config
>>>> +   maybe-extra-config-list
>>>> +   "Extra configuration values to append to the fonts.conf."))
>>>> +
>>>> +(define (add-fontconfig-config-file user-config)
>>>>    `(("fontconfig/fonts.conf"
>>>>       ,(mixed-text-file
>>>>         "fonts.conf"
>>>>         "<?xml version='1.0'?>
>>>>  <!DOCTYPE fontconfig SYSTEM 'fonts.dtd'>
>>>> -<fontconfig>
>>>> -  <dir>~/.guix-home/profile/share/fonts</dir>
>>>> -</fontconfig>"))))
>>>> +<fontconfig>"
>>>> +       (serialize-configuration user-config home-fontconfig-configuration-fields)
>>>
>>> Just a thought for the future and a point for configuration module
>>> improvements: It would be cool if serialize-configuration and all other
>>> serialize- functions returned a G-exps, this way we could write
>>> something like that:
>>>
>>> (home-fontconfig-configuration
>>>  (font-directories (list (file-append font-iosevka "/share/fonts"))))
>>
>> Nice.
>>
>> Thanks,
>> --
>> Taiju

Thanks,
--
Taiju