I am trying to do some deep code analysis on a python2 codebase that is large and messy enough that most analysis tools I've tried have not worked. I have however been able to use pycscope to generate a cscope database. I can even use it to do basic things like find function usages or all functions called directly from a given function.
To me, it seems like the fact that there is a database and that it can be used for simple things means that it should be possible to use it for more complex things too. For example if I wanted to find all functions that are called from within a given function recursively, or all codepaths that depend on that function.
However cscope documentation is very light and I'm not much of a c-expert. Is there an actual query language for it? An extension that knows how to use the database in this manner?
Related
So iOS 6 deprecates presentModalViewController:animated: and dismissModalViewControllerAnimated:, and it replaces them with presentViewController:animated:completion: and dismissViewControllerAnimated:completion:, respectively. I suppose I could use find-replace to update my app, although it would be awkward with the present* methods, since the controller to be presented is different every time. I know I could handle that situation with a regex, but I don't feel comfortable enough with regex to try using it with my 1000+-files-big app.
So I'm wondering: Does Xcode have some magic "update deprecated methods" command or something? I mean, I've described my particular situation above, but in general, deprecations come around with every OS release. Is there a better way to update an app than simply to use find-replace?
You might be interested in Program Transformation Systems.
These are tools that can automatically modify source code, using pattern-directed source-to-source transformations ("if you see this source-level pattern, replace it by that source-level pattern") that operate on code structures rather than text. Done properly, these transformations can be reliable and semantically correct, and they're a lot easier to write than low-level procedural code that navigates and smashes nanoscopic actual tree structures.
It is not the case that using such tools is easy; such tools have to know how to parse the language of interest into compiler data structures, (e.g., ObjectiveC), process the patterns, and regenerate compilable source code from the modified structures. Even with the basic transformation engine, somebody needs to carefully define parsers (and unparsers!) for the dialects of the languages of interest. And it takes time to learn how to use such a even if you have such parsers/unparsers. This is worth it if the changes you need to make are "regular" (in the program transformation sense, not the regexp sense) and widespread (as yours seem to be).
Our DMS Software Reengineering toolkit has an ObjectiveC front end, and can carry out such transformations.
no there is no magic like that
I would like to know if the following is possible in Scala (but I think the question can be applied also to Java):
Create a Scala file dynamically (ok, no problem here)
Compile it (I don't think this would be a real problem)
Load/Unload the new class dynamically
Aside from knowing if dynamic code loading/reloading is possible (it's possible in Java so I think it's feasible also in Scala) I would like also to know the implication of this in terms of performance degradation (I could have many many classes, with no name clash but really many of them!).
TIA!
P.S.: I know other questions about class loading in Scala exist, but I haven't been able to find an answer about performance!
Yes, everything you want to do is certainly possible. You might like to take a look at ScalaMock, which is an example of creating Scala source code dynamically. And at SBT which is an example of calling the compiler from code. And then there are many different systems that load classes dynamically - look at the documentation for loadLibrary as a starting point.
But, depending on what you want to achieve, you might like to look at Scala Macros instead. They provide the same kind of flexibility as you would get by generating source code and then compiling it, but without many of the downsides of that approach. The original version of ScalaMock used to work by generating source code, but I'm in the process of moving to using macros instead.
It's all possible in Scala, as is clearly demonstrated by the REPL. It's even going to be relatively easy with Scala 2.10.
(Mathematica version: 8.0.4)
lst = Names["Internal`*"];
Length[lst]
Pick[lst, StringMatchQ[lst, "*Bag*"]]
gives
293
{"Internal`Bag", "Internal`BagLength", "Internal`BagPart", "Internal`StuffBag"}
The Mathematica guidebook for programming By Michael Trott, page 494 says on the Internal context
"But similar to Experimental` context, no guarantee exists that the behavior and syntax of the functions will still be available in later versions of Mathematica"
Also, here is a mention of Bag functions:
Implementing a Quadtree in Mathematica
But since I've seen number of Mathematica experts here suggest Internal`Bag functions and use them themselves, I am assuming it would be sort of safe to use them in actual code? and if so, I have the following question:
Where can I find a more official description of these functions (the API, etc..) like one finds in documenation center? There is nothing now about them now
??Internal`Bag
Internal`Bag
Attributes[Internal`Bag]={Protected}
If I am to start using them, I find it hard to learn about new functions by just looking at some examples and trial and error to see what they do. I wonder if someone here might have a more complete and self contained document on the use of these, describe the API and such more than what is out there already or a link to such place.
The Internal context is exactly what its name says: Meant for internal use by Wolfram developers.
This means, among other things, the following things hold about anything you might find in there:
You most likely won't be able to find any official documentation on it, as it's not meant to be used by the public.
It's not necessarily as robust about invalid arguments. (Crashing the kernel can easily happen on some of them.)
The API may change without notice.
The function may disappear completely without notice.
Now, in practice some of them may be reasonably stable, but I would strongly advise you to steer away from them. Using undocumented APIs can easily leave you in for a lot of pain and a nasty surprise in the future.
I understand that over a thousand built-in rewrite rules in Mathematica populate the global rules table by default. Is there any way to get Mathematica to give a full or even partial list of those rules?
The best way is to get a job at Wolfram Research.
Failing that, I think that for things not completely compiled into the kernel you can recover most of the rules/definitions. Look at
Attributes[fn]
where fn is the command that you're interested in. If it returns
{Protected, ReadProtected}
then there's something you can get a look at (although often it's just a MakeBoxes (formatting) definition or a AutoLoad/Stub type definition). To see what's there run
Unprotect[fn];
ClearAttributes[fn, ReadProtected];
??fn
Quite often you'll have to run an example of the command to load it if it was a stub. You'll also have to dig down from the user-facing commands to the back-end implementations.
Eventually you'll most likely reach a core command that is compiled into the kernel that you can not see the details of.
I previously mentioned this in tips for creating Graph diagrams and it got a mention in What is in your Mathematica tool bag?.
An good example, with a nice bite-sized and digestible bit of code is Experimental`AngularSlider[] mentioned in Circular/Angular slider. I'll leave it up to you to look at the code produced.
Another example is something like BoxWhiskerChart, where you need to call it once in order to load all of the code. Then you see that BoxWhiskerChart proceeds to call Charting`iBoxWhiskerChart which you'll have to unprotect to look at, etc...
How can I include the procedures from one Netlogo file into another? Basically, I want to separate the code of a genetic algorithm from my (quite complicated) fitness function, but, obviously, I want the fitness reporter, which will reside in "fitness.nlogo", to be available in the genetic algorithm code, probably "genetic.nlogo".
If it can be done, how are the procedures imported, and the code executed? Is it like Python, where importing a module pretty much executes everything in the module, or like C/C++, where the file is blindly "joined"?
This may be a stupid question, but I couldn't find anything on Google. The Netlogo documentation says something about __includes, an experimental keyword that may do the trick, but there's not much explained there. No example either.
Any hints? Should I go with __includes? How does it work?
To include a file you use
__includes["libfile.nls"]
After adding this and pressing the “Check” button, a new button will appear next to the Procedures drop-down menu. There you can create and manage multiple source files.
The libfile.nls is just a text file that contains NetLogo code. It is not a netlogo model, which always end in .nlogo, as a NetLogo model contains a lot of other information besides the NetLogo code.
Including a file is the equivalent of just inserting all its contents at that point. In order to make it work in a way like reusable library files, one should create procedures which use agentsets and parameters as input variables to be independent of global definitions or interface settings.
The feature is documented in the NetLogo User Manual at http://ccl.northwestern.edu/netlogo/docs/programming.html#includes.
You can create a file libfile.nls and in the same folder create your main model model.nlogo.
After that, go to your model.nlogo and write:
__includes["libfile.nls"]
This file contains your reporters and procedures that you can call in your model.