Control@{h[3], 0, 1}
It is puzzling. (The motive for h[i] is to build a list of controls.)
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1 Answer
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6
It seems that Control is just a wrapper for Manipulate`Control, and that function expects a Symbol as its first argument:
Control[]; (*preload*)
ClearAttributes[Manipulate`Control, {Protected, ReadProtected}]
Block[{$Context = "Manipulate`Dump`"},
Definition[Manipulate`Control] // Print;
]
Manipulate`Control[var_, Manipulate`Dump`opts___Rule, ControlType -> type_, opts2___Rule] := Manipulate`Control[var, type, Manipulate`Dump`opts, opts2] Manipulate`Control[var_Symbol, Manipulate`Dump`opts : OptionsPattern[]] := Manipulate`Control[var, Automatic, Manipulate`Dump`opts] Manipulate`Control[{var_Symbol, args___}, Manipulate`Dump`opts : OptionsPattern[]] := Manipulate`Control[{var, args}, Automatic, Manipulate`Dump`opts] . . .
All but the first definition use _Symbol which requires that the Head of the expression be Symbol, and the first definition just calls one of the others.
This seems like an oversight as one can easily configure a slider with h[3]:
Dynamic[h[3]]
Slider[Dynamic[h[3]], {0, 1}]
answered Mar 1, 2016 at 16:12
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$\begingroup$ Thank you @Mr.Wizard . The code you wrote is somewhat too complicated for me but I understand the comment following it.
Manipulatetoo allowsh[3]. But what is Manipulate`Control? $\endgroup$– User18Commented Mar 1, 2016 at 16:33 -
1$\begingroup$ @User18
Manipulate`Controlseems to be the internal function thatControlis transformed into the course of evaluation and Front End formatting. I am attempting to follow internal definitions to arrive at this conclusion. The point is that if I am correct andControlrelies uponManipulate`Control, and the latter only works with Symbols, then the observed behavior is expected if disappointing. $\endgroup$ Commented Mar 1, 2016 at 17:05 -
$\begingroup$ That's most helpful. It is strange that in the MMA Documentation I cannot find information about it, nor the usage of the ` sign acting not as a number mark. Then where should I look them up? $\endgroup$– User18Commented Mar 2, 2016 at 2:58
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1$\begingroup$ @User18
Manipulate`Controlis an internal, behind-the-scenes function and I would not expect to find documentation for it. The use of the backtick here is for Context; thisControlis in the contextManipulate`. The regularControlis in theSystem`context. See: reference.wolfram.com/language/tutorial/Contexts.html $\endgroup$ Commented Mar 2, 2016 at 11:34 -
$\begingroup$ [email protected] Having learned about contexts I now understand the code you posted. Thanks a lot! Ah, it seems we both had a little problem with typing code when the code contained the code wrapper. $\endgroup$– User18Commented Mar 2, 2016 at 14:15