# Tag Info

40

In version 10.1, I've built something like Spelunk into GeneralUtilities. To use it, run Needs["GeneralUtilities"] PrintDefinitions[symbol]; This will pop up a window that shows all definitions of symbol. Here is a short summary of features: The window shows code cells containing all DownValues, OwnValues, UpValues, SubValues, and Attributes of a ...

18

You should consider using the sandbox functionality. You can create a subkernel and put it in sandbox mode this way: link = LinkLaunch[First[$CommandLine]<> " -wstp -noicon"]; LinkWrite[link, Unevaluated@EvaluatePacket[DeveloperStartProtectedMode[]]]; You can then interact with this subkernel using the standard LinkWrite and LinkRead functions. If ... 14 The definitions aren't being lost, they're being shadowed, as described in the tutorial on contexts. Mathematica doesn't warn you about this because it only warns when there is shadowing between contexts that are listed in the$ContextPath. Since Begin only changes $Context and not$ContextPath, you don't get a warning when the symbol that causes shadowing ...

13

I have been solving exactly the same problem about 2 years ago (http://community.wolfram.com/groups/-/m/t/125587?p_p_auth=aZGMz5bs). Students are uploading piece of Mathematica (Wolfram Language) code which is run by a testing script (in Mathematica) and the results are compared with a reference solution. To prevent the students to run potentially dangerous ...

10

I will make no attempt to defend the fact that Mathematica simulates scoping by means of variable renaming. However, the behaviour that we see is consistent with the principles under which Mathematica does operate. Whenever Mathematica tries to interpret a symbol name, it first checks to see whether a symbol with that name already exists in a package in ...

10

I think the symbols sym and $m7res are created by Information. They are not present when the kernel is started. Fresh kernel 1: Quit[] Names["Global*"] (* {} *) Fresh kernel 2: Quit[] foo = Trace[ Information["Global*"], TraceInternal -> True]; foo[[8, 3, 5, 7, 2, 9, 18, 65, 2, 1, 3, 6, 7, 5, 6, 4, 3, 3, 6, 2, 8, 12, 10, 5, 6, 2, ... 8 Indeed confusing, but can be explained. Please read here first on how Mathematica searches contexts for symbols. In short,$Context tells it where to create symbols. It's for creation, not for lookup. $ContextPath tells it where to look for symbols but doesn't affect symbol creation. If the symbol is not found in any of the$ContextPath contexts, ...

7

There are two things you need to know: (1.) Mathematica knows about symbols, even if you only mention them: This means that in this simple example 1 /. myVar_Integer :> 0 where myVar is only a placeholder (a named pattern) or like you call it a dummy, Mathematica still sees this symbol and adds it to its symbol table Names["Global*"] (* {"myVar"} *) ...

6

It seems that when the book appeared, the behaviour of how a symbol is resolved was different. We have two important things: the current $Context which is usually Global unless you change it with e.g. Begin as you did the$ContextPath which is a list of contexts that are searched when you type in a symbol like x without explicit context Now there seems ...

6

If I understand the problem I think I can help, but what I propose is a bit weird. I think you have a package that uses the unqualified Symbol name Order internally, and you need the package not to see the SystemOrder Symbol while it is defined. To effect this you can temporarily change the Context of Order, then put it back after loading the package. As ...

6

And if there is a possibility to manually use it for something useful? Yes, it solves a problem I had many times and which I had to work around. And none of those work arounds was as general as a following method. The case you are writing a package that exports a function GenerateModule[] which creates new notebook/cdf. (let's say each instance has ...

5

We can replace something, in all definitions associated with a symbol, using function like this: ClearAll[replaceExtendedDefinition] SetAttributes[replaceExtendedDefinition, HoldFirst] replaceExtendedDefinition[sym_, rules_] := Replace[ LanguageExtendedDefinition[sym] , (rule:Rule | RuleDelayed)[lhs_, rhs_] :> ...

5

ReadList seems to work as you intended when used instead of Get in your code: ClearAll["file1*", "file2*"] Begin["file1"] ReadList["file1.txt", "Expression"] End[] Begin["file2"] ReadList["file2.txt", "Expression"] End[] On my system, I obtain: ?file1* Alternatively you can of course check the values themselves: a (* Out: a *) ...

5

I was digging around one day and I found appropriate function for this. FrontEndExecute@FrontEndPrivateGetUpdatedSymbolContexts[]; will help if you read a package or clear symbols from different place than the notebook interface. CreatePalette[ Button["Clear", Clear["Global*"]; FrontEndExecute@FrontEndPrivateGetUpdatedSymbolContexts[]; , ...

5

From the comments: But I'm mainly worried about the warning messages that Mathematica issues when I load both packages. If the packages are properly written, and if the symbol conflict is between two packages (and not builtins and a package function), then you can safely ignore it. From the documentation of BeginPackage: BeginPackage["context"] ...

4

Note: shown below is an answer to the first version of the OP's question Here is a simple example using scoping constructs, namely Block in this case. The idea is that you can indicate symbols to make local to Block, which implements dynamic scoping: take a look at the "Background and Context" section of its docs for a more complete explanation. Symbols ...

4

As @MarcoB states, you should probably use scoping constructs... If you're opposed to that idea, you can set the Notebooks default context to be Unique to Each Cell Group. I wouldn't recommend that, but it works. You can set that under Evaluation > Notebook's Default Context > Unique to Each Cell Group: Note, to escape this, you need to specify ...

3

Every symbol always has a context. Most of the time we are in the Global context. $Context (* "Global" *) Normally we don't have to specify a variable as Globals Simply writing s is sufficient provided we are in the Global context. Inside your package the symbols and functions are defined in the SimulatorV2DebugPrivate context. In the function ... 3 I see the same behaviour, also using v10.2.0 on Win7/64. As to the "why", the sequence of events is as follows. As a matter of routine, Information generates a random cell tag for the display cell: This cell tag is generated using CreateUUID. CreateUUID, in turn, is autoloaded as part of a collection symbols all somewhat related to cloud functionality. ... 3 It is hard to answer you without you showing a minimal example of the problem. But my guess is that you are making the mistake of returning symbols from the package back to the user. The way to handle these things, is to do like all Mathematica functions do, which is pass the symbols needed in the call itself. For example, when using DSolve or Integrate, ... 3 It is a matter of having the right$ContextPath at the time n is referenced. This is slightly complicated by the fact that contexts are interpreted at parse time, so typical tricks such as Block do not work. The behavior of Begin and BeginPackage are also different with respect to $ContextPath, but this is all discussed in the documentation, so I will let ... 3 This is messy and imperfect, but it will work in simple cases: Import the package contents: pack = ImportString[data, {"Package", "HeldExpressions"}] (* {HoldComplete[BeginPackage["Test"]], HoldComplete[testFunction::usage = "-";], HoldComplete[Begin["Private"]], HoldComplete[testFunction[] := {123, explicitvalue, Hold[explicitvalue]};], ... 3 I think this is a caching problem. Considering the examples in the Update documentation it certainly makes sense that this could be the case. Although Update appears to have no effect I have found something that does: Information. x = 1; Context[x] = "foo"; x foox Context[x] 1 1 "foo" ?x foox x=1 x foox Context[x] x 1 "Global" ... 3 You can make use of Formal Symbols. BeginPackage["Test"]; replace::usage = "Returns \[FormalV]/.rules."; Begin["Private"]; replace[rules_] := \[FormalV] /.rules End[]; EndPackage[]; Then in the notebook. replace[\[FormalV] -> 0] (* 0 *) Hope this helps. 3 is there some way to take the call ReplaceAll[var, rules]and make it forget contexts for a minute? BeginPackage["Test"]; replace::usage = "Returns var/.rules."; print; Begin["Private"]; replace[rules_] := ReplaceAll[Symbol[$Context <> "var"], rules] End[]; EndPackage[]; Not general, but works. I would expect that replace[rules_] := ...

2

(this is wiki answer, as just noticed it is duplicate, but will keep it here for easy reference) The result is different from Version 2.2 and version 10.1, this is just to show the difference. Something changed between 1993 and today:

2

Try replace[rules_] := ReplaceAll[Globalvar, rules] in your function. Then replace[var -> 0] replace[TestPrivatevar -> 0] yields 0 var as I think you'd like.

2

i am doing the same thing as you did，and i am using MSP module which is a security solution for webMathmatica。please refer my topic How to adapt MSPToExpression function in $PrePrint? sandbox seems another good solution for security，mathematica online is using it。 can i ask whether you solved this by using sandbox？ 1 What's happening is that the expression is being read in and parsed before being evaluated, which means that the symbols Symbolize and ParsedBoxWrapper are created before the "Notation" context is placed on the$ContextPath by Needs. Without seeing the symbols in "Notation", Mathematica creates them in the "Global" context, leading to the shadowing. You ...

1

To summarize the comments by me and Szabolcs into an answer, these will be running in different instances (separate processes) of the same kernel executable. There is a related note in the documentation of the WolframScript interpreter, Each of the Wolfram Language scripts running concurrently starts its own kernel, with no shared variables or ...

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