Why can't I use this
Where[{iw, ih} = ImageDimensions[i], ...]
instead of this
Where[dim = ImageDimensions[i], iw = dim[[1]], ih = dim[[2]], ...]
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$\begingroup$ Excuse me, why the down-vote? This is a good question that might expose a limitation of the core language, perhaps you don't care for language design? $\endgroup$– M.R.Commented Mar 4, 2015 at 1:05
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1$\begingroup$ It has very little value in my opinion. But I reversed my down-vote. $\endgroup$– m_goldbergCommented Mar 4, 2015 at 1:10
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$\begingroup$ possible duplicate of A smarter nested With? $\endgroup$– Leonid ShifrinCommented Mar 4, 2015 at 1:57
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1 Answer
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Presumably you are referring to Where from the "GeneralUtilities"` package.
You can see the definition for yourself:
Attributes[Where] = {HoldAll}
Where[expr_] := expr
Where[x_List, expr_] := With[x, expr]
Where[x_, expr_] := With[{x}, expr]
Where[x_, rest__, expr_] := Where[x, Where[rest, expr]]
Where[s : Verbatim[Set][x_List, y_], rest___, expr_] :=
With[{x2 = Quiet[Replace[Hold[x], z_Symbol :> z_, {2}]]},
Replace[y, {HoldPattern @@ x2 :> Where[rest, expr], _ -> $Failed}]]
If it is not written as you would like use this for inspiration and write your own. :-)
answered Mar 4, 2015 at 1:15
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1$\begingroup$ Ah, that casts some real light on the question. I still think the question is badly posed. $\endgroup$ Commented Mar 4, 2015 at 1:17