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Re: thing-at-point: inconsistent behaviour?
From: |
Raffaele Ricciardi |
Subject: |
Re: thing-at-point: inconsistent behaviour? |
Date: |
Fri, 17 Aug 2012 10:23:40 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux i686; rv:14.0) Gecko/20120713 Thunderbird/14.0 |
On 08/17/2012 05:38 AM, Drew Adams wrote:
>>> In the case of a symbol, IMO most programs really want/need
>>> to grab a symbol _name_, often for use as the default value
>>> in an interactive spec. Most do not really want/need a Lisp
>>> symbol. And even when they do, they can call `intern'
>>> or `intern-soft' or `make-symbol' themselves.
>>
>> Then they should call (thing-at-point 'symbol), not
>> (symbol-at-point).
>
> Yes.
>
> On the other hand, for many such use cases it is not very useful to
obtain a
> value of `nil' (a symbol, not a string) when there is no symbol name
at point
> (not even "nil"). Function `non-nil-symbol-name-at-point' returns ""
in that
> case. It is, in effect, (or (thing-at-point 'symbol) "").
>
>> It seems like this tangent is because someone thought that the
>> latter should just be a shorthand for the former, but they do
>> different things and are intended for different situations. If
>> symbol-at-point doesn't do what you want (e.g. it interns things
>> when you would prefer it didn't), don't use it. No one's forcing
>> you to.
>
> Exactly. And not just "someone" - such confusion does not seem that
rare.
>
> You might have come to understand that (thing-at-point 'symbol) returns a
> string, and you correctly distinguish it from what `symbol-at-point'
does, but
> it is easy for others not to get this.
>
>
> This confusion wrt symbols is why it is helpful to provide a function
that has
> `symbol-name' and not just `symbol' in its name, the former doing, in
effect,
> what (or (thing-at-point 'symbol) "") does.
>
> BTW, I don't think most use cases really care whether or not the name
has been
> interned. What is more important usually is what kind of value is
returned: a
> symbol or a string (symbol name).
>
> The other thing that can be important for some use cases is to
distinguish the
> absence of any symbol name at point from the presence of the symbol
name "nil"
> at point. When picking up a symbol name to serve as a completion
candidate for
> some input, it is often the case that "nil" is not appropriate.
>
> FWIW, this 2007 Emacs Devel thread discusses exactly what is being
discussed in
> the present thread, and a bit more:
>
> http://lists.gnu.org/archive/html/emacs-devel/2007-07/msg01520.html
>
>
Indeed there is ambiguity in the naming of `symbol-at-point', for as
Drew has
pointed out in another reply of his, `symbol' is a context-sensitive term,
e.g. an Emacs Lisp symbol or a symbol according to the active syntax
table. As
such, users could oversee that `symbol-at-point' works only in the
context of
Emacs Lisp programs. As a counterexample, the specificity of
`list-at-point'
and 'sexp-at-point' is obvious. Maybe `symbol-at-point' could document
that it
returns the interned Emacs Lisp symbol at point, thus avoiding any
confusion?
Also, the documentation string could redirect to `thing-at-point' - or
to a new
`symbol-name-at-point' function - users who want to distinguish between no
symbol and `nil'.
> Especially since `thing-at-point' does NOT always return a string -
> it returns a
> list for (thing-at-point 'list), for instance. There is nothing in
the name,
> i.e., on the surface of it, that tells you that (thing-at-point
'symbol) returns
> either a symbol name or the symbol `nil'. It looks every bit like it
might
> return the thing at point that is a symbol.
On my GNU Emacs 24.1, `thing-at-point' always returns a (propertized)
string,
including when used with 'list.
- RE: thing-at-point: inconsistent behaviour?, (continued)
- RE: thing-at-point: inconsistent behaviour?, Drew Adams, 2012/08/15
- Re: thing-at-point: inconsistent behaviour?, Raffaele Ricciardi, 2012/08/15
- Re: thing-at-point: inconsistent behaviour?, Andreas Röhler, 2012/08/16
- Message not available
- Re: thing-at-point: inconsistent behaviour?, Barry Margolin, 2012/08/16
- Re: thing-at-point: inconsistent behaviour?, Andreas Röhler, 2012/08/16
- Message not available
- Re: thing-at-point: inconsistent behaviour?, Raffaele Ricciardi, 2012/08/16
- Re: thing-at-point: inconsistent behaviour?, Barry Margolin, 2012/08/16
- RE: thing-at-point: inconsistent behaviour?, Drew Adams, 2012/08/16
- Message not available
- Re: thing-at-point: inconsistent behaviour?, Barry Margolin, 2012/08/16
- RE: thing-at-point: inconsistent behaviour?, Drew Adams, 2012/08/17
- Message not available
- Re: thing-at-point: inconsistent behaviour?,
Raffaele Ricciardi <=
- RE: thing-at-point: inconsistent behaviour?, Drew Adams, 2012/08/19