Skip to main content

Find names of the functions defined in a file


Lets say I have a file named file.m that contains:



test[] := (
  Print["test"]
)

How would I go about extracting the function declarations in such a file consistently as a list?


I have figured out how to extract the data without having it execute.


Import["file.m", "Text"]

This is my current code.


Cases[

 FullForm[
  MakeExpression[Import["file.m", "Text"], TraditionalForm]
  ],
 SetDelayed[x__, y__] -> f[x, y]
 ]

Answer



Preamble


This is not such an easy task actually, if you want to do this fast and clean. I have been developing some functionality for one of my side projects, for which I needed to analyze symbols inside packages, so I will share some of the code I ended up with.


Speed


The following function will be two orders of magnitude faster than the one based on Import[...,"HeldExpressions"]:



ClearAll[loadFile];
loadFile[path_String?FileExistsQ]:=
    DeleteCases[            
        ToExpression[
            FromCharacterCode[BinaryReadList[path]],InputForm,HoldComplete
        ],
        Null
    ]

hopefully this function is still robust enough.



Benchmarks


Benchmarks on a medium-size package:


file = FileNameJoin[{$InstallationDirectory,"SystemFiles","Links","JLink", "JLink.m"}];

Do[Import[file, "HeldExpressions"], {100}] // AbsoluteTiming
Do[loadFile[file], {100}] // AbsoluteTiming

(*

  {4.351563, Null}

  {0.153320, Null}
*)

The format of the result of loadFile is a little different - it just wraps all code in one HoldComplete. But it is easy to transform to the partial HoldComplete wrapped around the pieces.


The speed difference can be quite important (for my application it was. I would have been in trouble using Import).


Namespace pollution


The problem


Perhaps even worse than the speed issue is the one of namespace pollution, which is a flaw shared by both methods described so far. The new symbols are being created as a result of parsing the code, and they are created in whatever happens to be the current working context. For example, for the case at hand:


Names["Global`*`*"]//Short


(* 
  {Global`Private`arg,Global`Private`arg$,Global`Private`e,
  <<21>>,Global`Private`val,Global`Private`val$,Global`Package`$jlinkDir}
*)

Sugegsted solution


With the implementation details described at the bottom of the post, here is the way I ended up doing this: I introduced the macro with the following signature:


withHeldCodeInTemporaryContext[{var_Symbol, code_}, fname_, opts : OptionsPattern[]]

which is supposed to read in the file fname, parse it into some temporary context, assign the result to a variable var, then execute the code code, and finally clean up that temporary context. Here is an example of use (you will need to run the code posted below for it to work):



Block[
{       
   heldCode,
   file=
      FileNameJoin[
         {$InstallationDirectory,"SystemFiles","Links","JLink","JLink.m"}
      ]
},
   withHeldCodeInTemporaryContext[          
      {             

         heldCode,
         Union[
            Cases[heldCode,s_Symbol:>ToString[Unevaluated[s]],\[Infinity],Heads->True]
         ]
      },
      file
   ]
]

This code collects all the symbols which build up the code being read. The result looks like:



(*
  {And,AppendTo,BeginPackage,Blank,Check,Close,  
  <<78>>,$ContextPath,$Failed,$Input,$Off,$SystemID,$VersionNumber}
*)

but one can check that the working context (or any other context) was not polluted.


Implementation


Here is the code (formatting done using the code formatter palette):


SetAttributes[CleanUp,HoldAll];
CleanUp[expr_,cleanup_]:=

   Module[{exprFn,result,abort=False,rethrow=True,seq},          
      exprFn[]:=
         expr;
      result=
         CheckAbort[                
            Catch[Catch[result=exprFn[];rethrow=False;result],_,seq[##1]&],
            abort=True
         ];
      cleanup;
      If[abort,Abort[]];

      If[rethrow,Throw[result/. 
         seq->Sequence]];
      result
   ]

SetAttributes[parseInContext,HoldFirst];    
Options[parseInContext]=
   {          
      LocalizingContext->"MyLocalizingContext`",
      DefaultImportedContexts:>{},

      ExtraImportedContexts:>{}
   };    
parseInContext[code_,opts:OptionsPattern[]]:=
   Module[
   {          
      result,
      context=OptionValue[LocalizingContext],
      defcontexts=OptionValue[DefaultImportedContexts],
      extraContexts=OptionValue[ExtraImportedContexts],
      allContexts

   },          
      allContexts={Sequence@@defcontexts,Sequence@@extraContexts};          
      Block[{$ContextPath},             
         CleanUp[                
            BeginPackage[context];Needs/@allContexts;result=code,
            EndPackage[]
         ];
         result
      ]
   ];



ClearAll[inPrivateContext];
SetAttributes[inPrivateContext,HoldAll];
inPrivateContext[code_]:=
   CleanUp[Begin["`Private`"];code,End[]];


ClearAll[parseInPrivateSubcontext];
SetAttributes[parseInPrivateSubcontext,HoldFirst];

parseInPrivateSubcontext[code_,opts:OptionsPattern[]]:=
   parseInContext[inPrivateContext[code],opts];


ClearAll[withTemporaryContext];
SetAttributes[withTemporaryContext,HoldRest];
withTemporaryContext[context_String,{contVar_Symbol,code_}]:=
   Block[{contVar=context},
      With[{names=context<>"Private`*",remove=If[Names[#1]=!={},Remove[#1]]&},
         CleanUp[remove[names];code,remove[names]]

      ]
   ];


ClearAll[withHeldCodeInTemporaryContext];
Options[withHeldCodeInTemporaryContext]=
   {          
      TemporaryContextName->"TemporaryContext`",
      ExtraImportedContexts:>{"Global`"}
   };

SetAttributes[withHeldCodeInTemporaryContext,HoldFirst];    
withHeldCodeInTemporaryContext[
   {var_Symbol,code_},fname_,opts:OptionsPattern[]
]:=
   Module[{tempcont},
      Block[{var},
         withTemporaryContext[                
            OptionValue[TemporaryContextName],
            {                   
               tempcont,

               parseInPrivateSubcontext[                      
                  var=loadFile[fname];code,
                  LocalizingContext->tempcont,
                  ExtraImportedContexts->OptionValue[ExtraImportedContexts]
               ]
            }
         ]
      ]
   ];


The code contains a number of macros,some of which are general (like WReach's CleanUp and a few others), while others specialize the generic ones to the more narrow goals we set here.


Comments

Post a Comment

Popular posts from this blog

plotting - Filling between two spheres in SphericalPlot3D

Manipulate[ SphericalPlot3D[{1, 2 - n}, {θ, 0, Pi}, {ϕ, 0, 1.5 Pi}, Mesh -> None, PlotPoints -> 15, PlotRange -> {-2.2, 2.2}], {n, 0, 1}] I cant' seem to be able to make a filling between two spheres. I've already tried the obvious Filling -> {1 -> {2}} but Mathematica doesn't seem to like that option. Is there any easy way around this or ... Answer There is no built-in filling in SphericalPlot3D . One option is to use ParametricPlot3D to draw the surfaces between the two shells: Manipulate[ Show[SphericalPlot3D[{1, 2 - n}, {θ, 0, Pi}, {ϕ, 0, 1.5 Pi}, PlotPoints -> 15, PlotRange -> {-2.2, 2.2}], ParametricPlot3D[{ r {Sin[t] Cos[1.5 Pi], Sin[t] Sin[1.5 Pi], Cos[t]}, r {Sin[t] Cos[0 Pi], Sin[t] Sin[0 Pi], Cos[t]}}, {r, 1, 2 - n}, {t, 0, Pi}, PlotStyle -> Yellow, Mesh -> {2, 15}]], {n, 0, 1}]
Post a Comment
Read more

plotting - Plot 4D data with color as 4th dimension

I have a list of 4D data (x position, y position, amplitude, wavelength). I want to plot x, y, and amplitude on a 3D plot and have the color of the points correspond to the wavelength. I have seen many examples using functions to define color but my wavelength cannot be expressed by an analytic function. Is there a simple way to do this? Answer Here a another possible way to visualize 4D data: data = Flatten[Table[{x, y, x^2 + y^2, Sin[x - y]}, {x, -Pi, Pi,Pi/10}, {y,-Pi,Pi, Pi/10}], 1]; You can use the function Point along with VertexColors . Now the points are places using the first three elements and the color is determined by the fourth. In this case I used Hue, but you can use whatever you prefer. Graphics3D[ Point[data[[All, 1 ;; 3]], VertexColors -> Hue /@ data[[All, 4]]], Axes -> True, BoxRatios -> {1, 1, 1/GoldenRatio}]
Post a Comment
Read more

plotting - Mathematica: 3D plot based on combined 2D graphs

I have several sigmoidal fits to 3 different datasets, with mean fit predictions plus the 95% confidence limits (not symmetrical around the mean) and the actual data. I would now like to show these different 2D plots projected in 3D as in but then using proper perspective. In the link here they give some solutions to combine the plots using isometric perspective, but I would like to use proper 3 point perspective. Any thoughts? Also any way to show the mean points per time point for each series plus or minus the standard error on the mean would be cool too, either using points+vertical bars, or using spheres plus tubes. Below are some test data and the fit function I am using. Note that I am working on a logit(proportion) scale and that the final vertical scale is Log10(percentage). (* some test data *) data = Table[Null, {i, 4}]; data[[1]] = {{1, -5.8}, {2, -5.4}, {3, -0.8}, {4, -0.2}, {5, 4.6}, {1, -6.4}, {2, -5.6}, {3, -0.7}, {4, 0.04}, {5, 1.0}, {1, -6.8}, {2, -4.7}, {3, -1.
Post a Comment
Read more