Re: Idiomatic way to avoid unused lexical variable in ‘dotimes’ or ‘dolist’?

[tpeplt]

Tim Landscheidt <tim@tim-landscheidt.de> writes:

>
>>>> 1. Is there an idiom in Emacs Lisp for writing this that
>>>>    eliminates this warning?
>
>>>     (dotimes (_ 100)
>>>       (insert "I will not obey absurd orders\n"))
>
>>> Or any other var name that starts with an underscore.
>
>> Thank you.  I have not been able to find this documented anywhere (that
>> is, that lexical variables whose names begin with an underscore are not
>> flagged with a warning message if they are not referenced).  This
>> appears to be true with, for example, ‘let’ expressions, also.
>
> It is mentioned in the GNU Emacs Lisp Reference Manual (C-h
> i g (elisp) RET) in the node "Converting to Lexical
> Binding":
>
> | […]
>
> |    A warning about an unused variable may be a good hint that the
> | variable was intended to be dynamically scoped (because it is actually
> | used, but in another function), but it may also be an indication that
> | the variable is simply really not used and could simply be removed.  So
> | you need to find out which case it is, and based on that, either add a
> | ‘defvar’ or remove the variable altogether.  If removal is not possible
> | or not desirable (typically because it is a formal argument and that we
> | cannot or don’t want to change all the callers), you can also add a
> | leading underscore to the variable’s name to indicate to the compiler
> | that this is a variable known not to be used.)
>
> | […]
>

Again, thank you.  This will be useful knowledge in future instances of
variables that have to be declared, but are not referenced.

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