Skip to main content

parsing - FullForm with context for each symbol?


FullForm strips the context for any symbol that can be found on the Append[$ContextPath, $Context]: FullForm[System`List] is displayed List, but I would like to get System`List for debugging and learning purposes.


I tried $ContextPath = {} but then the whole front-end stops working [1].


Is there another way besides


Hold[...] /. x_Symbol :> (Context@x <> SymbolName@Unevaluated@x)

Is there any case where this would not work?




[1] I find it strange that the internal code of the FrontEnd relies on the "usability features" $Context and $ContextPath. Why doesn't it use the full symbol names for any code it uses (or produces)? IMO $ContextPath = {} should hurt you (having to type the full name of any symbols not in $Context), but not the system. If it really needs System` to operate properly, it should not allow setting $ContextPath = {} just like it is not allowed to set $Context to something invalid.


[2] Note that Context has HoldFirst while SymbolName doesn't, hence the Unevaluated.



Answer





  1. To not mess with $ContextPath you can Block it just for that evaluation. e.g. Block[{$ContextPath = {}}, ...].


    But we don't want to do that for the evaluation, input for FullForm should be evaluated freely and only the result should be returned with full symbols' names.


    To achieve that you should know:





  2. $ContextPath and $Context affect the typesetting. MakeBoxes will strip those contexts from an evaluated FullForm.




So, to deal with 2 we have to perform MakeBoxes on our rules (local contexts values) and order that to not be touched by MakeBoxes anymore (RawBoxes):


Block[{$ContextPath = {}, $Context = "other`"}
   ,
   RawBoxes @ ToBoxes @ FullForm @ {x, 1}
] 



System`List[Global`x,1]

It is very convenient when we want to "toggle a visibility" of specific contexts:


Block[{$ContextPath = {"System`"}, ...


 List[Global`x,1]

Comments

Post a Comment

Popular posts from this blog

functions - Get leading series expansion term?

Given a function f[x] , I would like to have a function leadingSeries that returns just the leading term in the series around x=0 . For example: leadingSeries[(1/x + 2)/(4 + 1/x^2 + x)] x and leadingSeries[(1/x + 2 + (1 - 1/x^3)/4)/(4 + x)] -(1/(16 x^3)) Is there such a function in Mathematica? Or maybe one can implement it efficiently? EDIT I finally went with the following implementation, based on Carl Woll 's answer: lds[ex_,x_]:=( (ex/.x->(x+O[x]^2))/.SeriesData[U_,Z_,L_List,Mi_,Ma_,De_]:>SeriesData[U,Z,{L[[1]]},Mi,Mi+1,De]//Quiet//Normal) The advantage is, that this one also properly works with functions whose leading term is a constant: lds[Exp[x],x] 1 Answer Update 1 Updated to eliminate SeriesData and to not return additional terms Perhaps you could use: leadingSeries[expr_, x_] := Normal[expr /. x->(x+O[x]^2) /. a_List :> Take[a, 1]] Then for your examples: leadingSeries[(1/x + 2)/(4 + 1/x^2 + x), x] leadingSeries[Exp[x], x] leadingSeries[(1/x + 2 + (1 - 1/x...
Post a Comment
Read more

How to thread a list

I have data in format data = {{a1, a2}, {b1, b2}, {c1, c2}, {d1, d2}} Tableform: I want to thread it to : tdata = {{{a1, b1}, {a2, b2}}, {{a1, c1}, {a2, c2}}, {{a1, d1}, {a2, d2}}} Tableform: And I would like to do better then pseudofunction[n_] := Transpose[{data2[[1]], data2[[n]]}]; SetAttributes[pseudofunction, Listable]; Range[2, 4] // pseudofunction Here is my benchmark data, where data3 is normal sample of real data. data3 = Drop[ExcelWorkBook[[Column1 ;; Column4]], None, 1]; data2 = {a #, b #, c #, d #} & /@ Range[1, 10^5]; data = RandomReal[{0, 1}, {10^6, 4}]; Here is my benchmark code kptnw[list_] := Transpose[{Table[First@#, {Length@# - 1}], Rest@#}, {3, 1, 2}] &@list kptnw2[list_] := Transpose[{ConstantArray[First@#, Length@# - 1], Rest@#}, {3, 1, 2}] &@list OleksandrR[list_] := Flatten[Outer[List, List@First[list], Rest[list], 1], {{2}, {1, 4}}] paradox2[list_] := Partition[Riffle[list[[1]], #], 2] & /@ Drop[list, 1] RM[list_] := FoldList[Transpose[{First@li...
Post a Comment
Read more

front end - keyboard shortcut to invoke Insert new matrix

I frequently need to type in some matrices, and the menu command Insert > Table/Matrix > New... allows matrices with lines drawn between columns and rows, which is very helpful. I would like to make a keyboard shortcut for it, but cannot find the relevant frontend token command (4209405) for it. Since the FullForm[] and InputForm[] of matrices with lines drawn between rows and columns is the same as those without lines, it's hard to do this via 3rd party system-wide text expanders (e.g. autohotkey or atext on mac). How does one assign a keyboard shortcut for the menu item Insert > Table/Matrix > New... , preferably using only mathematica? Thanks! Answer In the MenuSetup.tr (for linux located in the $InstallationDirectory/SystemFiles/FrontEnd/TextResources/X/ directory), I changed the line MenuItem["&New...", "CreateGridBoxDialog"] to read MenuItem["&New...", "CreateGridBoxDialog", MenuKey["m", Modifiers-...
Post a Comment
Read more