When I raise my owns exceptions in my Python libraries, the exception stack shows the raise-line itself as the last item of the stack. This is obviously not an error, is conceptually right, but points the focus on something that is not useful for debugging when you're are using code externally, for example as a module.
Is there a way to avoid this and force Python to show the previous-to-last stack item as the last one, like the standard Python libraries.
Due warning: modifying the behaviour of the interpreter is generally frowned upon. And in any case, seeing exactly where an error was raised may be helpful in debugging, especially if a function can raise an error for several different reasons.
If you use the traceback module, and replace sys.excepthook with a custom function, it's probably possible to do this. But making the change will affect error display for the entire program, not just your module, so is probably not recommended.
You could also look at putting code in try/except blocks, then modifying the error and re-raising it. But your time is probably better spent making unexpected errors unlikely, and writing informative error messages for those that could arise.
you can create your own exception hook in python. below is the example of code that i am using.
import sys
import traceback
def exceptionHandler(got_exception_type, got_exception, got_traceback):
listing = traceback.format_exception(got_exception_type, got_exception, got_traceback)
# Removing the listing of statement raise (raise line).
del listing[-2]
filelist = ["org.python.pydev"] # avoiding the debuger modules.
listing = [ item for item in listing if len([f for f in filelist if f in item]) == 0 ]
files = [line for line in listing if line.startswith(" File")]
if len(files) == 1:
# only one file, remove the header.
del listing[0]
print>>sys.stderr, "".join(listing)
And below are some lines that I have used in my custom exception code.
sys.excepthook = exceptionHandler
raise Exception("My Custom error message.")
In the method exception you can add file names or module names in list "filenames" if you want to ignore any unwanted files. As I have ignored the python pydev module since I am using pydev debugger in eclipse.
The above is used in my own module for a specific purpose. you can modify and use it for your modules.
I'd suggest to not use the Exception mechanism to validate arguments, as tempting as that is. Coding with exceptions as conditionals is like saying, "crash my app if, as a developer, I don't think of all the bad conditions my provided arguments can cause. Perhaps using exceptions for things not only out of your control but also which is under control of something else like the OS or hardware or the Python language would be more logical, I don't know. In practice however I use exceptions as you request a solution for.
To answer your question, in part, it is just as simple to code thusly:
class MyObject(object):
def saveas(self, filename):
if not validate_filename(filename):
return False
...
caller
if not myobject.saveas(filename): report_and_retry()
Perhaps not a great answer, just something to think about.
I'm working on a relatively large SML codebase. It was originally written to compile with MLton, but I'm now working with it under SML/NJ. I need to use RedBlackMapFn, which is defined in smlnj-lib.cm. However, I get an error:
elaborate/elaborate-bomenv.fun:9.20-9.27 Error: unbound signature: ORD_KEY
elaborate/elaborate-bomenv.fun:14.21-14.40 Error: unbound functor: RedBlackMapFn
elaborate/elaborate-bomenv.fun:32.20-32.27 Error: unbound signature: ORD_KEY
elaborate/elaborate-bomenv.fun:37.21-37.40 Error: unbound functor: RedBlackMapFn
So I assume that smlnj-lib.cm is not being pulled by CM. In an effort to fix this, I added $/smlnj-lib.cm to the sources.cm file in the directory that I'm working in. This causes a separate issue:
elaborate/sources.cm:25.1-25.18 Error: structure Random imported from $SMLNJ-LIB/Util/smlnj-lib.cm#243997(random.sml) and also from ./(sources.cm):lib/(sources.cm):basic/(sources.cm):random.sml
elaborate/sources.cm:25.1-25.18 Error: structure Queue imported from $SMLNJ-LIB/Util/smlnj-lib.cm#436143(queue.sml) and also from ./(sources.cm):lib/(sources.cm):basic/(sources.cm):two-list-queue.sml
No dice. I tried removing the Random structure that's coming from ./(sources.cm):lib/(sources.cm):basic/(sources.cm):random.sml, but it appears that it isn't equivalent to the one defined in the standard library, so I can't just substitute one for the other.
I'd like to use something like Python's import ... from ... as ...
mechanism to give a new name to the Random that's coming from the standard library, but CM's documentation doesn't offer any hints as to how I'd go about that.
How can I resolve a module naming conflict across multiple SML files?
I ended up splitting off the problematic file in to a separate .cm. The problem file here is elaborate-bomenv.{sig, fun}. The .cm file for this directory is sources.cm, which caused errors when it looked like:
Group
...
is
$/basis.cm
...
elaborate-bomenv.fun
elaborate-bomenv.sig
...
So instead, I made an elaborate-bomenv-sources.cm that looks like:
Group
signature ELABORATE_BOMENV
functor BOMEnv
is
$/smlnj-lib.cm
...
elaborate-bomenv.sig
elaborate-bomenv.fun
and changed the original sources.cm to read:
Group
...
is
$/basis.cm
...
./elaborate-bomenv-sources.cm
...
Which is ugly, but it works.
I'm trying to generate a class diagram, using reverse engineering, but the following is happening:
There was an error parsing C:\Documents and Settings\Meus documentos\EA_Documentos\Modelos\Environment\class\Factory.h on line 11. Unexpected symbol: ISIMFactory
You may need to define a language macro.
There was an error parsing C:\Documents and Settings\Meus documentos\EA_Documentos\Modelos\Environment\class\Model.h on line 99. Unexpected symbol: ISIMModel
You may need to define a language macro.
There are many more of these.
This is the corresponding code in CSIMEnvironmentModel.h
class SIMMDLENVv01_EXPORT CSIMEnvironmentModel // line 99
: public ISIMModel
, public ISIMEventSource
, public ISIMScheduledModel
, public ISIMExecut
, public ISIMPublisher
{
public:
CSIMEnvironmentModel(const std::string &a_modelType);
virtual ~CSIMEnvironmentModel(void);
and CSIMEnvFactory.h
class SIMMDLENVv01_EXPORT CSIMEnvFactory // line 11
: public ISIMFactory
{
public:
CSIMEnvFactory();
virtual ~CSIMEnvFactory(void);
std::vector<ISIMModel*> InstanceModel(const std::string &a_modelType, const std::string &a_conf);
};
What's the reason for this error message?
Your code contains usage of a macro definition (SIMMDLENVv01_EXPORT) that isn't part of EA's standard macro definitions (there's whole a lot of them covering ATL and MFC mostly).
You'll need to add additional ones under 'Settings->Language Macros' (as the hint in the error message suggests).
NOTE
Use the syntax MACRO() when declaring macros that were #defined to receive any number of arguments.
If you're trying to reverse engineer framework libraries like Qt or alike, you'll need to set many of these that you're able to reverse engineer the code without getting errors.
May be you should think of a different strategy to reference these types and classes in your model then.
Another workaround might be to solely preprocess all the code you want to import first, and import from the preprocessed results.
So...I have a kernel mode component and a user mode component I'm putting together using the turnkey build environment of the NT DDK 7.1.0. The kernel component is all .c/.h/.rc files. The user mode component is .cpp/.c/.h/.rc files.
At first it seemed simplest to use build for both, as I saw you could modify the ./sources file of the user mode component to say something like:
TARGETNAME = MyUserModeComponent
TARGETTYPE = PROGRAM
UMTYPE = windows
UMENTRY = winmain
USE_MSVCRT = 1
That didn't seem to cause a problem and so I was pleased, until I tried to #include <string> (or <memory>, or whatever) Doesn't find that stuff:
error C1083: Cannot open include file: 'string': No such file or directory
Still, it's compiling the user mode piece with C++ language semantics. But how do I get the standard includes to work?
I don't technically need to use the DDK build tool for the user mode piece. I could make a visual studio solution. I'm a bit wary as I have bumped into other annoyances, like the fact that the DDK uses __stdcall instead of __cdecl by default... and there isn't any pragma or compiler switch to override this. You literally have to go into each declaration you care about and change it, assuming you have source to do so. :-/
I'm starting to wonder if this is just a fractal descent into "just because you CAN doesn't mean you SHOULD build user mode apps with the DDK. Here be dragons." So my question isn't just about this particular technical hurdle, but rather if I should abandon the idea of building a C++ user mode component with the DDK tools...just because the kernel component is pure C.
To build a user mode program with WINDDK you need to add some variables to your SOURCES file:
386_STDCALL=0 to use cdecl calling convention by default
USE_STL=1 to use STL
USE_NATIVE_EH=1 to add a support for exception handling
Everything else you already have.
I'll put my full SOURCES file for reference:
TARGETNAME = MyUserModeComponent
TARGETTYPE = PROGRAM
TARGETPATH = obj
UMTYPE = console
UMENTRY = main
USE_MSVCRT = 1
USE_NATIVE_EH=1
USE_STL=1
386_STDCALL=0
SOURCES= main.cpp
And main.cpp:
#include <iostream>
#include <string>
using namespace std;
int main()
{
string s = "bla bla bla!";
cout << s;
return 0;
}
Have fun!
Quick Answer
Abandon the idea of building user-mode components with DDK tools (although I find the concept fascinating :-P)
Your kernel mode component should be built separately from the user mode components as a matter of good practice.
Vague thoughts
Off the top of my head, and this really speaking from limited experience...there are a lot of subtle differences that can creep up if you try to mix the two together.
Using your own example of __cdecl vs __stdcall; You have two different calling conventions. _cdecl is all kernel stuff and all of the C++ methods are wrapped around in WINAPI (_stdcall) passing conventions and __stdcall will clean do auto stack clean up and expect frame pointers inserted all over the place. And if you by accident use compiler options to trigger a __fastcall, it would be a pain to debug.
You can definitely hack something together, but do you really want to keep track of that in your user-space code and build environment? UGH I say.
Unless you have very specific engineering reasons to mix the two environments, (and no a unified build experience is not a valid reason, because you can get that from a batch file called buildall.bat) I say use the separate toolchains.
I was trying hard to make ANTLR 3.2 generate parser/lexer in C++. It was fruitless. Things went well with Java & C though.
I was using this tutorial to get started: http://www.ibm.com/developerworks/aix/library/au-c_plusplus_antlr/index.html
When I checked the *.stg files, I found that:
CPP has only
./tool/src/main/resources/org/antlr/codegen/templates/CPP/CPP.stg
C has so many files:
./tool/src/main/resources/org/antlr/codegen/templates/C/AST.stg
./tool/src/main/resources/org/antlr/codegen/templates/C/ASTDbg.stg
./tool/src/main/resources/org/antlr/codegen/templates/C/ASTParser.stg
./tool/src/main/resources/org/antlr/codegen/templates/C/ASTTreeParser.stg
./tool/src/main/resources/org/antlr/codegen/templates/C/C.stg
./tool/src/main/resources/org/antlr/codegen/templates/C/Dbg.stg
And so other languages.
My C.g file:
grammar C;
options { language='CPP'; }
/** Match things like "call foo;" */
r : 'call' ID ';' {System.out.println("invoke "+$ID.text);} ;
ID: ('a'..'z'|'A'..'Z'|'_')('0'..'9'|'a'..'z'|'A'..'Z'|'_')* ;
WS: (' ' |'\n' |'\r' )+ {$channel=HIDDEN;} ; // ignore whitespace
Errors:
error(10): internal error: group Cpp does not satisfy interface ANTLRCore: missing templates [lexerRuleRefAndListLabel, parameterSetAttributeRef, scopeSetAttributeRef, returnSetAttributeRef, lexerRulePropertyRef_text, lexerRulePropertyRef_type, lexerRulePropertyRef_line, lexerRulePropertyRef_pos, lexerRulePropertyRef_index, lexerRulePropertyRef_channel, lexerRulePropertyRef_start, lexerRulePropertyRef_stop, ruleSetPropertyRef_tree, ruleSetPropertyRef_st]
error(10): internal error: group Cpp does not satisfy interface ANTLRCore: mismatched arguments on these templates [outputFile(LEXER, PARSER, TREE_PARSER, actionScope, actions, docComment, recognizer, name, tokens, tokenNames, rules, cyclicDFAs, bitsets, buildTemplate, buildAST, rewriteMode, profile, backtracking, synpreds, memoize, numRules, fileName, ANTLRVersion, generatedTimestamp, trace, scopes, superClass, literals), optional headerFile(LEXER, PARSER, TREE_PARSER, actionScope, actions, docComment, recognizer, name, tokens, tokenNames, rules, cyclicDFAs, bitsets, buildTemplate, buildAST, rewriteMode, profile, backtracking, synpreds, memoize, numRules, fileName, ANTLRVersion, generatedTimestamp, trace, scopes, superClass, literals), lexer(grammar, name, tokens, scopes, rules, numRules, labelType, filterMode, superClass), rule(ruleName, ruleDescriptor, block, emptyRule, description, exceptions, finally, memoize), alt(elements, altNum, description, autoAST, outerAlt, treeLevel, rew), tokenRef(token, label, elementIndex, hetero), tokenRefAndListLabel(token, label, elementIndex, hetero), listLabel(label, elem), charRangeRef(a, b, label), ruleRef(rule, label, elementIndex, args, scope), ruleRefAndListLabel(rule, label, elementIndex, args, scope), lexerRuleRef(rule, label, args, elementIndex, scope), lexerMatchEOF(label, elementIndex), tree(root, actionsAfterRoot, children, nullableChildList, enclosingTreeLevel, treeLevel)]
error(10): internal error: C.g : java.lang.IllegalArgumentException: Can't find template actionGate.st; group hierarchy is [Cpp]
... and so on.
Please kindly advise. Thank you! I'm using Leopard 10.5.8 with
CLASSPATH=:/Users/vietlq/projects/antlr-3.2.jar:/Users/vietlq/projects/stringtemplate-3.2.1/lib/stringtemplate-3.2.1.jar:/Users/vietlq/projects/stringtemplate-3.2.1/lib/antlr-2.7.7.jar
It sounds like you've answered your own question: ANTLR's C++ lexer/parser generators are not yet functional.
For what it's worth, it's still possible to use ANTLR for parsing from C++, via the C target. I use ANTLR to generate a C language lexer and parser, which I then compile and link to my C++ code.
I have one C++ file that translates an ANTLR parse tree to my target abstract syntax tree classes, and the rest of my code doesn't care where the AST comes from. It works pretty well in practice! It would be easy to replace ANTLR with a different parser generator, and I find that the separation leads to cleaner ANTLR grammars.
I have posted a C++ Target for ANTLR. Please check it out.