I'm embedding Python into a C++ application. I plan to use PyEval_EvalCode to execute Python code, but instead of providing the locals and globals as dictionaries, I'm looking for a way to have my program resolve symbol references dynamically.
For example, let's say my Python code consists of the following expression:
bear + lion * bunny
Instead of placing bear, lion and bunny and their associated objects into the dictionaries that I'm passing to PyEval_EvalCode, I'd like the Python interpreter to call back my program and request these named objects.
Is there a way to accomplish this?
By providing the locals and globals dictionaries, you are providing the environment in which the evaled code is executed. That effectively provides you with an interface to map names to objects defined in the C++ app.
Can you clarify why you do not want to use the dictionaries?
Another thing you could do is process the string in C++ and do string substitution before you eval the code....
Possibly. I've never tried this but in theory you might be able to implement a small extension class in C++ that overrides the __getattr__ method (probably via the tp_as_mapping or tp_getattro function pointers of PyTypeObject). Pass an instance of this as locals and/or globals to PyEval_EvalCode and your C++ method should be asked to resolve your lions, tigers, & bears for you.
Related
I've been trying a solution for this, but. I cannot find it.
What I'm trying to do, is work with the "bind by reference" ability, but working with ILE RPG written with embedded sql.
I can use the BNDDIR ctl opt in my source. And everything works correctly.
But that means a "bind by copy" method. Checked deleting the SRVPGM and even the BINDDIR. And the caller program still works.
So, is there any way to use "bind by reference" in an ILERPGSQL program?
After my question, an example:
Program SNILOG is a module, that conains several procedures. Part of them, exported.
In QSRVSRC I set the exported procedures, with a source with the same name: SNILOG. Something like this:
STRPGMEXP PGMLVL(*CURRENT)
/************************************************** ******************/
/* *MODULE SNILOG INIGREDI 04/10/21 15:25:30 */
/************************************************** ******************/
EXPORT SYMBOL("GETDIAG_TOSTRING")
EXPORT SYMBOL("GETDIAGNOSTICS")
EXPORT SYMBOL("GRABAR_LOG")
EXPORT SYMBOL("SNILOG")
ENDPGMEXP
As part of the procedures are programmed with embedded sql, the compilation must be done with CRTSQLRPGI, using the parameter OBJTYPE(*SRVPGM).
So, I finally get a SRVPGM called SNILOG, with those 4 procedures exported.
Once I've got the SRVPGM, I add it to a BNDDIR called SNI_BNDDIR.
Ok, let's go to the caller program: SNI600V.
Defined with
dftactgrp(*no)
, of course!.
And compiled with CRTSQLRPGI and parameter OBJTYPE(*PGM).
Here, if I use the control spec
bnddir('SNI_BNDDIR')
, it works fine.
But not fine enough, as this is a "bind by copy" method (I can delete the SRVPGM or the BNDDIR, and it is still working fine).
When I'm not working with SQL, I can use the CRTPGM command, and I can set the BNDSRVPGM parameter, to set the SRVPGM the program is going to be called. Well, just their procedures...
But I cannot find any similar option in CRTSQLRPGI command.
Nor in opt codes in ctl-opt sentence (We have BNDDIR, but not BNDSRVPGM option).
Any idea?
I'm running V7R3M0 with TR level: 6
Thanks in advance!
the use of
bnddir('SNI_BNDDIR')
Is the way to bind by reference OR bind by copy.
The key is what does your BNDDIR look like?
If you want to bind by reference, then it should include *SRVPGM objects.
If you want to bind by copy, then it should include *MODULE objects.
Generally, you want a *BNDDIR for every *SRVPGM that includes the modules (and maybe a utility *SRVPGM or two) needed for building a specific *SRVPGM.
Then one or more *BNDDIR that includes just *SRVPGM objects that are used to build the programs that use those *SRVPGMs.
I implement MyClass containing the method method() and I store the instance in $_ENV['key'] in test.php. Also in test.php the code completion works when I type $_ENV['key']->.
In test2.php I include test.php and the code completion does not work any more for $_ENV['key']->.
Does anyone know how to enable this in PhpStorm?
AFAIK type tracking for arrays works within the same file only.
You can bypass it via intermediate variable (yes, it's not a nicest solution) and small PHPDoc comment, like this:
/** #var MyClass $myVar */
$myVar = $_ENV['key'];
$myVar->
P.S.
In general, I'd suggest not using global arrays this way (or even not using global vars at all -- only very basic stuff during bootstrap, if possible). Instead (based on your code) I may suggest using some static class (as one of the alternatives) with dedicated field where you can easily give type hint (via PHPDoc) to a class field -- this way IDE will always know hat type it is. Current PHP versions (5.5 and especially 5.6) work with objects nearly as fast as with arrays, even leading in (smaller) memory consumption.
Obviously, such suggestion does not really apply if this code is not yours.
I'm doing some competitions on a website called topcoder.com where the objective is to solve algorithmic problems. I'm using Eclipse for this purpose, and I code in Java, it would be help me to have some predefined templates or macros that I can use for common coding tasks. For example I would like to write methods to be able to find the max value in and int[] array, or the longest sequence in an int[] array, and so on (there should be quite many of these). Note I can't write these methods as libraries because as part of the competition I need to submit everything in one file.
Therefore ideally, I would like to have some shortcut available to generate code both as a method and as a calling statement at once. Any ideas if this is possible?
Sure you can - I think that's a nifty way to auto-insert boilerplate or helper code. To the point of commenters, you probably want to group the code as a helper class, but the general idea sounds good to me:
You can see it listed in your available templates:
Then as you code your solution, you can Control+Space, type the first few characters of the name you gave your template, and you can preview it:
And then you can insert it. Be sure if you use a class structure to position it as an inner class:
Lastly - if you want to have a template inserts a call to method from a template, I think you would just use two templates. One like shown above (to print the helper code) and another that might look like this, which calls a util method and drops the cursor after it (or between the parentheses if you'd like, etc):
MyUtils.myUtilMethod1();${cursor}
Ruby has this very interesting functionality in which when you create a class with 'Class.new' and assign it to a constant (uppercase), the language "magically" sets up the name of the class so it matches the constant.
# This is ruby code
MyRubyClass = Class.new(SuperClass)
puts MyRubyClass.name # "MyRubyClass"
It seems ruby "captures" the assignment and inserts sets the name on the anonymous class.
I'd like to know if there's a way to do something similar in Lua.
I've implemented my own class system, but for it to work I've got to specify the same name twice:
-- This is Lua code
MyLuaClass = class('MyLuaClass', SuperClass)
print(MyLuaClass.name) -- MyLuaClass
I'd like to get rid of that 'MyLuaClass' string. Is there any way to do this in Lua?
When assigning to global variables you can set a __newindex metamethod for the table of globals to catch assignments of class variables and do whatever is needed.
You can eliminate one of the mentions of MyLuaClass...
> function class(name,superclass) _G[name] = {superclass=superclass} end
> class('MyLuaClass',33)
> =MyLuaClass
table: 0x10010b900
> =MyLuaClass.superclass
33
>
Not really. Lua is not an object-orientated language. It can behave like one sometimes. But far from every time. Classes are not special values in Lua. A table has the value you put in it, no more. The best you can do is manually set the key in _G from the class function and eliminate having to take the return value.
I guess that if it REALLY, REALLY bothers you, you could use debug.traceback(), get a stack trace, find the calling file, and parse it to find the variable name. Then set that. But that's more than a little overkill.
With respect at least to Lua 5.2: You can capture assignments to A) the global table of a Lua State, as mentioned in a previous reply, and also B) to any other Lua Object whose __index and __newindex metamethods have been substituted (by replacing the metatable), this I can confirm as I'm currently using both these techniques to hook and redirect assignments made by Lua scripts to external C/C++ resource management.
There is a gotcha with regards to reading them back though, the trick is to NOT let the values be set in a Lua State.
As soon as they exist there, your hooks will fail to be called, so if you want to go down this path, you need to capture ALL get/set attempts, and NEVER store the values in a Lua State.
This is a little convoluted, but lets try:
I'm integrating LUA scripting into my game engine, and I've done this in the past on win32 in an elegant way. On win32 all I did was to mark all of the functions I wanted to expose to LUA as export functions. Then, to integrate them into LUA, I'd parse the PE header of the executable, unmangle the names, parse the parameters and such, then register them with my LUA runtime. This allowed me to avoid manually registering every function individually just to expose them to LUA.
Now, flash forward to today where I'm working on the iPhone. I've looked through some Unix stuff and I've gotten very close to taking a similar approach, however I'm not sure it will actually work.
I'm not entirely familiar with Unix, but here is what I have so far on iPhone:
Step 1: Query for the executable path through objective-C and get the path of my app
Step 2: Use dlopen to get a handle to my app using: `dlopen(path, RTLD_NOW)`
Step 3: Use `dlsym( libraryHandle, objectName )` to attempt to get the address of a known symbol.
The above steps won't actually get me to where I want to be, but even that doesn't work. Does anyone have any experience doing this type of thing on Unix? Are there any headers or functions I can google to put me on the right track?
Thanks;)
iPhone does not support dynamic linking after the initital application launch. While what you want to do does not actually require linking in any new application TEXT, it would not shock me to find out that some of the dl* functions do not behave as expected.
You may be able to write some platform specific code, but I recommend using a technique developed by the various BSDs called linker sets. Bascially you annotate the functions you want to do something with (just like you currently mark them for export). Through some preprocessor magic they store the annotations, sometimes in an extra segment in the binary image, then have code that grabs that data and enumerates its. So you simply add all the functions you want into the linker set, then walk through the linker set and register all the functions in it with lua.
I know people have gotten this stuff up and running on Windows and Linux, I have used it on Mac OS X and various *BSDs. I am linking the FreeBSD linker_set implementation, but I have not personally seen the Windows implementation.
You need to pass --export-dynamic to the linker (via -Wl,--export-dynamic).
Note: This is for Linux, but could be a starting point for your search.
References:
http://sourceware.org/binutils/docs/ld/Options.html
If static linking is an option, integrate that into the linker script. Before linking, do "nm" on all object files, extract the global symbols, and generate a C file containing a (preferably sorted/hashed) mapping of all symbol names to symbol values:
struct symbol{ char* name; void * value } symbols = [
{"foo", foo},
{"bar", bar},
...
{0,0}};
If you want to be selective in what you expose, it might be easiest to implement a naming schema, e.g. prefixing all functions/methods with Lua_.
Alternatively, you can create a trivial macro,
#define ForLua(X) X
and then grep the sources for ForLua, to select the symbols that you want to incorporate.
You could just generate a mapfile and use that instead, no?