I'm looking for an Actionscript equivalent for Python / PHP / etc.'s eval() function, which dynamically executes code from an arbitrary string.
There is no native eval() function. I see only one hack to do it : create a bytecode at runtime and load it. If you really need it, there are some cool libs that will do it for you :
http://eval.hurlant.com/
http://code.google.com/p/as3scriptinglib/
Related
I have a Clojurescript program running in the browser.
It imports a number of libraries, and then I want to allow the user to enter some small clojurescript "glue-code" that calls those libraries.
I can see (from https://cljs.github.io/api/cljs.js/eval) that you call eval with four arguments, the first being the state of the environment, which is an atom. But can I actually turn my current environment with all the functions I've required from elsewhere, into an appropriate argument to eval?
Update :
I thought that maybe I could set the namesspace for the eval using the :ns option of the third, opts-map, argument. I set it to the namespace of my application :
:ns "fig-pat.core"
But no difference.
Looking at the console, it's definitely the case that it's trying to do the evaluation, but it's complaining that names referenced in the eval-ed code are NOT recognised :
WARNING: Use of undeclared Var /square
for example. (square is a function I'm requiring. It's visible in the application itself ie. the fig-pat.core namespace)
I then get :
SyntaxError: expected expression, got '.'[Learn More]
Which I'm assuming this the failure of eval-ed expression as a whole.
Update 2 :
I'm guessing this problem might actually be related to : How can I get the Clojurescript namespace I am in from within a clojurescript program?
(println *ns*)
is just printing nil. So maybe Clojurescript can't see its own namespace.
And therefore the :ns in eval doesn't work?
Calling eval inside a clojurescript program is part of what is called "self-hosted clojurescript".
In self-hosted clojurescript, namespaces are not available unless you implement a resolve policy. It means that have to let the browser know how to resolve the namespace e.g. loads a cljs file from a cdn.
It's not so trivial to implement namespace resolving properly.
This is explained in a cryptic way in the docstring of load-fn from cljs.js namespace.
Several tools support namespaces resolving in self-host cljs running in the browser e.g Klipse and crepl
I'm trying to use Graphics32 package. Graphics32 was compiled and installed without any issue.
When I try to execute (debug) following code under C++ Builder XE3
TBitmap32* bmp = new TBitmap32();
bmp->LoadFromFile("d:\\sample.bmp");//This calls SaveToStream instead of LoadFromFile
...
it calls another member function SaveToStream which I can trace into and step while debugging until AV rises.
I have never encountered such behavior before.
Is there any compiler directive I'm missing or some workaround to make proper function call?
Update: I use the Graphics32 source from SVN. Everything works good if I use code prior to revision 2122.
I have a C++ method that takes variable argument as init param. Something like
MyMethod(std::wchar_t*, ...)
Can someone please let me know how can we write a WinRT component wrapper to expose the variable arguments?
WinRT metadata does not support vararg functions, so there is no good way to do this. The answer therefore depends on what the function actually does. Assuming it is some kind of string formatting function I would suggest wrapping it with something like:-
MyMethod(Platform::String^, Windows::Foundation::Collections::IVector<Platform::Object^>^ params);
This will allow you to take the variable arguments.
The problem of course is that this has completely different semantics from what you have. The caller is going to have to pack up an array, and you won't be able to call your existing method easily with the arguments from the vector.
So, I have an app where users should define ActionScript functions.
What do I need to get the string whritten by the user and convert it to bytecode so that I can use it with as3-commons-bytecode?
Edit
I don't think I was clear enough. I need to turn: if(!myValue) {...}
Into this:
...
findpropstrict private::myValue
getproperty private::myValue
not
iffalse L1
...
Because with this ^^^^ code, I can use as3-commons-bytecode to do what I need.
I took a look at this app's source code. It's very confusing, the project is old and the code is a mess, but it works. I need to find "where the magic happens". Can you show me the way?
You should use part of this project :
eval.hurlant.com/demo/#app=da4a&757d-selectedIndex=0
Check source , there is parser to ABC .
I'm not aware of any libraries that do this for you, but to achieve this functionality you should parse user's input into function names.
For example, you can call a function just by having it's name as a String like so:
var functionName:String = "myMethod";
function myMethod():void
{
trace("myMethod");
}
this[functionName](); //traces "myMethod"
Of course, if you wish to interpret advanced strings with getting/setting objects and their properties and any other user defined statements, that would require to write quite a sophisticated string-to-bytecode converter.
UPDATE:
There's also AS3Eval library that might do the job. Take a look at http://eval.hurlant.com/
There is a library for Haxe which makes it possible to compile Actionscript assembly language into ABC at runtime, but this is still lower-level than the Actionscript you normally write.
http://haxe.org/com/libs/format/abc
The most likely solution is a server or other process which can compile and return SWF content for you. Haxe has a very fast and straightforward compiler, but it may also be possible to use Tamarin or another solution for compiling AS3 on the server.
Actually, there is a runtime library for executing Haxe code, which again, is very similar to Actionscript. Might be worth looking into:
http://code.google.com/p/hscript/
What exactly want to do? To compile "string" the string must be something meanfull for the compiler such as package not a simply string ( like 'asdas ' ). If you don't wont to use flash/flex compiler you may compile AS to ABC with Ant or Haxe. But ther is a problem - how you will start this ABC?
I need to pass in a string that gets evaluated at runtime. So I can write this:
var foo = someEvalMethod ( "dataObject.someValue" )
instead of:
if ( argIn == "dataObject.someValue")
var foo = dataObject.someValue
}
Does anyone have an opinion on the following evaluate libraries, or better ones for AS3? Thanks:
AS3 eval by hurlant:
http://eval.hurlant.com/
D.eval by RIA 1:
http://www.riaone.com/products/deval/
As far as I know AS3 eval by hurlant is a "real" compiler. It parses code, generates bytecode and injects it to the Flash Player instance in use (through loadBytes() I guess).
D.eval has the same purpose but it does not generate bytecode, it parses expressions and execute them dynamically through its own API.
I see D.eval as a good candidate for what you are trying to achieve. It's not a full featured compiler, but it has enough APIs that cover many simple operations. Other than that it is a product that has a company behind, which is always a good guaranty.
Cheers!