Is it possible to assign custom attributes to symbols and check them later?
SetAttributes[a, b]
says
Attributes::attnf: b is not a known attribute.
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1 Answer
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No, I do not believe it is. As the documentation for your error message says:
The attributes available in each version of Mathematica are fixed and cannot be changed.
The system attributes are low level properties that fundamentally change the evaluation of symbols. I think it makes sense that these are not mixed with high-level user constructs, even though at times that would be quite convenient.
For an alternative remember that you can attach Options to a symbol, e.g.:
Options[a] = {"Attributes" -> {"b"}};
OptionValue[a, "Attributes"]
{"b"}
You could also use a single DownValues rule such as:
a["Attributes"] = {"b"};
a["Attributes"]
{"b"}
answered Jan 19, 2013 at 10:07
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$\begingroup$ Thanks. But how to change individual option of a symbol? $\endgroup$ Jan 19, 2013 at 10:14
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$\begingroup$ @Suzan What do you mean? It is simple to replace the list of options with either method shown, e.g.
SetOptions[a, "Attributes" -> {"c", "d"}];ora["Attributes"] = {"c", "d"};Are you asking for a way to individually append or remove these values asSetAttributesandClearAttributesdo? I could add that to my answer if you have trouble crafting it yourself. $\endgroup$ Jan 19, 2013 at 10:17 -
$\begingroup$ @Suzan Thanks for the Accept, but please consider waiting a while first as someone else may have an answer you like better if you do not discourage them from reading the question. $\endgroup$ Jan 19, 2013 at 10:18