How can I include functions from a package into a CDF file?

Question

I am building an application which I would like to deploy as a CDF file, and I am struggling to make the CDF exports work correctly with functions pulled from a .m package file. What are good/best practices for handling such situations?

In particular, the code below encapsulates (at least partly) some of my difficulties. Make a package in the file TestPackage.m with the definitions

BeginPackage["TestPackage`"]
f::usage="f[x] returns a plot.";
Begin["`Private`"]
f[x_]:=Plot[Sin[x y],{y,0,2 Pi},PlotRange->{-1,1},ImageSize->500]
End[]
EndPackage[]

and include it in the same directory as the following code in a notebook.

Needs["TestPackage`", NotebookDirectory[] <> "TestPackage.m"]
DynamicModule[
 {a = 1},
 Column[{
   Slider[Dynamic[a]],
   Dynamic[f[a]]
   }]
 , Initialization :> (
   Needs["TestPackage`", NotebookDirectory[] <> "TestPackage.m"]
   )
 ]
Export[NotebookDirectory[] <> "output.cdf", EvaluationNotebook[]]

The DynamicModule correctly produces the desired output. If I close the notebook and reopen it, the plot renders correctly (which is not the case if the Initialization Needs is omitted). If I open the resulting output.cdf using Mathematica, the plot also renders correctly.

However, if I open output.cdf using the Wolfram CDF Player 10.1, the only thing that shows underneath the Slider is TestPackage`f[1.] (or whatever the value of a is).

I also tried naively spewing the contents of the package onto the initialization rule, along the lines of

Initialization :> (
 ImportString[Import[NotebookDirectory[] <> "TestPackage.m", "Text"],
   "NB"]
 )

but it produces exactly the same behaviour. Presumably there exists a way to do this, but this simply puts the above code into the CDF, which the player then refuses to execute.

How can I make this plot render correctly in the exported CDF version?

Answer 1

There are some doubts about using SaveDefinitions (1), (2), so let's implement a brute force approach which may be later used automatically.

---

Outline

Needs @ yourPackage  (*a*)


CDFDeploy @ With[
  { source = Import[packagePath] (*b*) }
, DynamicModule[
    { ... }
  , ...
  , Initialization :> ( Get @ StringToStream @ source )
]

• (a). You have to call your package before creating DynamicModule because you need all static content (not held/dynamic) in the body of DM to be parsed and evaluated properly.

And all dynamic/held names to be "typeset" with proper context name. And they will be found thanks to $ContextPath modified by BeginPackage and friends. (3)

• (b). We have to use With to inject source into DynamicModule's Initialization because Initialization is set with RuleDelayed which is HoldRest.

• For more complex/time consuming packages you may want to change SynchronousInitialization->False and monitor the state of initialization analogously to:

Working with DynamicModule: Tracking the progress of Initialization

---

###Execution

First code block is only to create a test package:

content = "
  BeginPackage[\"TestPackage`\"]
  f::usage=\"f[x] returns a plot.\";
  Begin[\"`Private`\"]
  f[x_]:=Plot[Sin[x y],{y,0,2 Pi},PlotRange->{-1,1},ImageSize->500]
  End[]
  EndPackage[]";

path = FileNameJoin[{$TemporaryDirectory, "package.m"}];
pathEnc = FileNameJoin[{$TemporaryDirectory, "package.enc"}];
pathCDF = FileNameJoin[{$TemporaryDirectory, "CDF.cdf"}]

Export[path, content, "Text"];

Now the actual code:

Encode[path, pathEnc];  (*c*)
encodedpackage = Import[pathEnc, "Text"];


Get @ pathEnc (*a*)

CDFDeploy[ pathCDF, #, Method -> "Standalone", "Target" -> "CDFPlayer"
] & @ 
With[ { source = encodedpackage (*b*) }
, DynamicModule[{x = 1}
  , Column[{
      Dynamic[{x, f[x]}],
      Button["x++", x++],
      Dynamic @ $ContextPath
    }]
  , Initialization :> Module[{stream}
    , stream = StringToStream @ source
    ; Get @ stream
    ; Close @ stream
    ]
  ]
]

c. we are Encoding source, it is then obscure for others and already compressed so why not. You can even incorporate password protection with this method: (4). It won't be fully secure, as pointed in comments here: (5).

You can now go to the CDF and test in the FreePlayer:

SystemOpen @ DirectoryName @ pathCDF

---

###Links

(1) The dangers of SaveDefinitions

(2) Not FullDefinition for Save. MachineID not Protected?

(3) load a Mathematica package inside a DynamicModule

(4) Encode->Import->StringToStream->Get on password-locked stream

(5) How to create protected single-file stand-alone CDF applications