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• Using clang to analyze C++ code

  - by aneccodeal

  We want to do some fairly simple analysis of user's C++ code and then use that information to instrument their code (basically regen their code with a bit of instrumentation code) so that the user can run a dynamic analysis of their code and get stats on things like ranges of values of certain numeric types. clang should be able to handle enough C++ now to handle the kind of code our users would be throwing at it - and since clang's C++ coverage is continuously improving by the time we're done it'll be even better. So how does one go about using clang like this as a standalone parser? We're thinking we could just generate an AST and then walk it looking for objects of the classes we're interested in tracking. Would be interested in hearing from others who are using clang without LLVM.

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• Using the Specification Pattern

  - by Kane

  Like any design pattern the Specification Pattern is a great concept but susceptible to overuse by an eager architect/developer. I am about to commence development on a new application (.NET & C#) and really like the concept of the Specification Pattern and am keen to make full use of it. However before I go in all guns blazing I would be really interested in knowing if anyone could share the pain points that experienced when use the Specification Pattern in developing an application. Ideally I'm looking to see if others have had issues in Writing unit tests against the specification pattern Deciding which layer the specifications should live in (Repository, Service, Domain, etc) Using it everywhere when a simple if statement would have done the job etc? Thanks in advance

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• Is there a log file analyzer for log4j files?

  - by Juha Syrjälä

  I am looking for some kind of analyzer tool for log files generated by log4j files. I am looking something more advanced than grep? What are you using for log file analysis? I am looking for following kinds of features: The tool should tell me how many time a given log statement or a stack trace has occurred, preferably with support for some kinds of patterns (eg. number of log statements matching 'User [a-z]* logged in'). Breakdowns by log level (how many INFO, DEBUG lines) and by class that initiated the log message would be nice. Breakdown by date (how many log statements in given time period) What log lines occur commonly together? Support for several files since I am using log rolling Hot spot analysis: find if there is a some time period when there is unusually high number of log statements Either command-line or GUI are fine Open Source is preferred but I am also interested in commercial offerings My log4j configuration uses org.apache.log4j.PatternLayout with pattern %d %p %c - %m%n but that could be adapted for analyzer tool.

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• build .pyc prob

  - by Apache

  hi experts, i build .py as follow python /root/pyinstaller-1.4/Makespec.py test.py then python /root/pyinstaller-1.4/Build.py test.spec this working fine then i test to build with my .pyc as follow python /root/pyinstaller-1.4/Makespec.py test.pyc then python /root/pyinstaller-1.4/Build.pyc test.spec but its generating error as follow checking Analysis building because inputs changed running Analysis outAnalysis0.toc Analyzing: /root/pyinstaller-1.4/support/_mountzlib.py Analyzing: /root/pyinstaller-1.4/support/useUnicode.py Analyzing: test.pyc Traceback (most recent call last): File "/root/pyinstaller-1.4/Build.py", line 1160, in main(args[0], configfilename=opts.configfile) File "/root/pyinstaller-1.4/Build.py", line 1148, in main build(specfile) File "/root/pyinstaller-1.4/Build.py", line 1111, in build execfile(spec) File "test.spec", line 3, in pathex=['/root/test']) File "/root/pyinstaller-1.4/Build.py", line 245, in init self.postinit() File "/root/pyinstaller-1.4/Build.py", line 196, in postinit self.assemble() File "/root/pyinstaller-1.4/Build.py", line 314, in assemble analyzer.analyze_script(script) File "/root/pyinstaller-1.4/mf.py", line 559, in analyze_script co = compile(string.replace(stuff, "\r\n", "\n"), fnm, 'exec') TypeError: compile() expected string without null bytes why this error occur, cannot we build using .pyc, or there is other way to build it,

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• <100% Test coverage - best practices in selecting test areas

  - by Paul Nathan

  Suppose you're working on a project and the time/money budget does not allow 100% coverage of all code/paths. It then follows that some critical subset of your code needs to be tested. Clearly a 'gut-check' approach can be used to test the system, where intuition and manual analysis can produce some sort of test coverage that will be 'ok'. However, I'm presuming that there are best practices/approaches/processes that identify critical elements up to some threshold and let you focus your test elements on those blocks. For example, one popular process for identifying failures in manufacturing is Failure Mode and Effects Analysis. I'm looking for a process(es) to identify critical testing blocks in software.

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• how to exploit vulnerability in php

  - by Dr Deo

  i have never seen a buffer overflow exploit in live action. supporse I have found a server that seems to have vulnerabilities. Where can i get proof of the concept code preferably in c/c++ to exploit the vulnerability? eg i found this vulnerability Multiple directory traversal vulnerabilities in functions such as 'posix_access()', 'chdir()', 'ftok()' may allow a remote attacker to bypass 'safe_mode' restrictions. (CVE-2008-2665 and CVE-2008-2666). How can i get proof of concept code for educational purposes PS I am a student and my only desire is to learn

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• Java Concurrency: CAS vs Locking

  - by Hugo Walker

  Im currently reading the Book Java Concurrency in Practice. In the Chapter 15 they are speaking about the Nonblocking algorithms and the compare-and-swap (CAS) Method. It is written that the CAS perform much better than the Locking Methods. I want to ask the people which already worked with both of this concepts and would like to hear when you are preferring which of these concept? Is it really so much faster? Personally for me the usage of Locks is much clearer and easier to understand and maybe even better to maintain. (Please correct me if I am wrong). Should we really focus creating our concurrent code related on CAS than Locks to get a better performance boost or is sustainability a higher thing? I know there is maybe not a strict rule, when to use what. But I just would like to hear some opinions, experiences with the new concept of CAS.

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• Managed language for scientific computing software

  - by heisen

  Scientific computing is algorithm intensive and can also be data intensive. It often needs to use a lot of memory to run analysis and release it before continuing with the next. Sometime it also uses memory pool to recycle memory for each analysis. Managed language is interesting here because it can allow the developer to concentrate on the application logic. Since it might need to deal with huge dataset, performance is important too. But how can we control memory and performance with managed language?

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• In MySQL, what is the most effective query design for joining large tables with many to many relatio

  - by lighthouse65

  In our application, we collect data on automotive engine performance -- basically source data on engine performance based on the engine type, the vehicle running it and the engine design. Currently, the basis for new row inserts is an engine on-off period; we monitor performance variables based on a change in engine state from active to inactive and vice versa. The related engineState table looks like this: +---------+-----------+---------------+---------------------+---------------------+-----------------+ | vehicle | engine | engine_state | state_start_time | state_end_time | engine_variable | +---------+-----------+---------------+---------------------+---------------------+-----------------+ | 080025 | E01 | active | 2008-01-24 16:19:15 | 2008-01-24 16:24:45 | 720 | | 080028 | E02 | inactive | 2008-01-24 16:19:25 | 2008-01-24 16:22:17 | 304 | +---------+-----------+---------------+---------------------+---------------------+-----------------+ For a specific analysis, we would like to analyze table content based on a row granularity of minutes, rather than the current basis of active / inactive engine state. For this, we are thinking of creating a simple productionMinute table with a row for each minute in the period we are analyzing and joining the productionMinute and engineEvent tables on the date-time columns in each table. So if our period of analysis is from 2009-12-01 to 2010-02-28, we would create a new table with 129,600 rows, one for each minute of each day for that three-month period. The first few rows of the productionMinute table: +---------------------+ | production_minute | +---------------------+ | 2009-12-01 00:00 | | 2009-12-01 00:01 | | 2009-12-01 00:02 | | 2009-12-01 00:03 | +---------------------+ The join between the tables would be engineState AS es LEFT JOIN productionMinute AS pm ON es.state_start_time <= pm.production_minute AND pm.production_minute <= es.event_end_time. This join, however, brings up multiple environmental issues: The engineState table has 5 million rows and the productionMinute table has 130,000 rows When an engineState row spans more than one minute (i.e. the difference between es.state_start_time and es.state_end_time is greater than one minute), as is the case in the example above, there are multiple productionMinute table rows that join to a single engineState table row When there is more than one engine in operation during any given minute, also as per the example above, multiple engineState table rows join to a single productionMinute row In testing our logic and using only a small table extract (one day rather than 3 months, for the productionMinute table) the query takes over an hour to generate. In researching this item in order to improve performance so that it would be feasible to query three months of data, our thoughts were to create a temporary table from the engineEvent one, eliminating any table data that is not critical for the analysis, and joining the temporary table to the productionMinute table. We are also planning on experimenting with different joins -- specifically an inner join -- to see if that would improve performance. What is the best query design for joining tables with the many:many relationship between the join predicates as outlined above? What is the best join type (left / right, inner)?

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• The best way to organize WPF projects

  - by Mike

  Hello everybody, I've started recently to develop a new software in WPF, and I still don't know which is the best way to organize the application, to be more productive with Visual Studio and Expression Blend. I noticed 2 annoying things I'd like to solve: I'm using Code Contracts in my projects, and when I run my project with Expression Blend, it launches the static analysis of the code. How can I stop that? Which configuration of the project does Blend use by default? I've tried to disable Code Contracts in a new configuration. It works in VS as the static analysis is not launched, but it has no effects in Blend. I've thinked about splitting the Windows Application in 2 parts: the first one containing the views of the WPF (app.exe) and the second one being the core of the project, with the logic code (app.core.dll), and I would just open the former project in Blend. Any thoughts about that? Thanks in advance Mike

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• Dynamic function docstring

  - by Tom Aldcroft

  I'd like to write a python function that has a dynamically created docstring. In essence for a function func() I want func.__doc__ to be a descriptor that calls a custom __get__ function create the docstring on request. Then help(func) should return the dynamically generated docstring. The context here is to write a python package wrapping a large number of command line tools in an existing analysis package. Each tool becomes a similarly named module function (created via function factory and inserted into the module namespace), with the function documentation and interface arguments dynamically generated via the analysis package.

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• Plain-English tutorial on artificial neural networks?

  - by Stuart

  I've Googled, StackOverflowed, everything, and I cannot seem to find a tutorial I can understand. I understand the concept of genetic algorithms, and how to implement them, (Though I haven't tried) but I cannot grasp the concept of neural networks. I know vaguely how they work... And that's about it. Could someone direct me to a tutorial that could help someone who has not even graduated middle school yet? Sure, I'm several years ahead of the majority of people my grade, but I don't understand summation, (which I apparently need if I don't want a simple binary output) vectors, and other things that I apparently should know. Is there a simple, bare-bones tutorial for neural networks? After I learn the basics, I'll proceed to more difficult ones. Preferably, they would be in Java. Thanks!

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• what is a dispatcher

  - by taher chhabra

  can anyone please explain the concept of dispatcher, is it one dispatcher per thread or anything else

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• Covariance and contravariance in programming languages

  - by xdevel2000

  Can anyone explain me, the concept of covariance and contravariance in programming languages theory?

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• Simple database design and LINQ

  - by Anders Svensson

  I have very little experience designing databases, and now I want to create a very simple database that does the same thing I have previously had in xml. Here's the xml: <services> <service type="writing"> <small>125</small> <medium>100</medium> <large>60</large> <xlarge>30</xlarge> </service> <service type="analysis"> <small>56</small> <medium>104</medium> <large>200</large> <xlarge>250</xlarge> </service> </services> Now, I wanted to create the same thing in a SQL database, and started doing this ( hope this formats ok, but you'll get the gist, four columns and two rows): > ServiceType Small Medium Large > > Writing 125 100 60 > > Analysis 56 104 200 This didn't work too well, since I then wanted to use LINQ to select, say, the Large value for Writing (60). But I couldn't use LINQ for this (as far as I know) and use a variable for the size (see parameters in the method below). I could only do that if I had a column like "Size" where Small, Medium, and Large would be the values. But that doesn't feel right either, because then I would get several rows with ServiceType = Writing (3 in this case, one for each size), and the same for Analysis. And if I were to add more servicetypes I would have to do the same. Simply repetitive... Is there any smart way to do this using relationships or something? Using the second design above (although not good), I could use the following LINQ to select a value with parameters sent to the method: protected int GetHourRateDB(string serviceType, Size size) { CalculatorLinqDataContext context = new CalculatorLinqDataContext(); var data = (from calculatorData in context.CalculatorDatas where calculatorData.Service == serviceType && calculatorData.Size == size.ToString() select calculatorData).Single(); return data.Hours; } But if there is another better design, could you please also describe how to do the same selection using LINQ with that design? Please keep in mind that I am a rookie at database design, so please be as explicit and pedagogical as possible :-) Thanks! Anders

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• How do you measure latency in low-latency environments?

  - by Ajaxx

  Here's the setup... Your system is receiving a stream of data that contains discrete messages (usually between 32-128 bytes per message). As part of your processing pipeline, each message passes through two physically separate applications which exchange the data using a low-latency approach (such as messaging over UDP) or RDMA and finally to a client via the same mechanism. Assuming you can inject yourself at any level, including wire protocol analysis, what tools and/or techniques would you use to measure the latency of your system. As part of this, I'm assuming that every message that is delivered to the system results in a corresponding (though not equivalent) message being pushed through the system and delivered to the client. The only tool that I've seen on the market like this is TS-Associates TipOff. I'm sure that with the right access you could probably measure the same information using a wire analysis tool (ala wireshark) and the right dissectors, but is this the right approach or are there any commodity solutions that I can use?

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• Finding C++ static initialization order problems

  - by Fred Larson

  We've run into some problems with the static initialization order fiasco, and I'm looking for ways to comb through a whole lot of code to find possible occurrences. Any suggestions on how to do this efficiently? Edit: I'm getting some good answers on how to SOLVE the static initialization order problem, but that's not really my question. I'd like to know how to FIND objects that are subject to this problem. Evan's answer seems to be the best so far in this regard; I don't think we can use valgrind, but we may have memory analysis tools that could perform a similar function. That would catch problems only where the initialization order is wrong for a given build, and the order can change with each build. Perhaps there's a static analysis tool that would catch this. Our platform is IBM XLC/C++ compiler running on AIX.

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• How to implement following with Zend navigation?

  - by simple

  I have a top navigation and a side one Home | Tours | Booking Tour1 ------ Tour2 ------ Tour3 I show the side menu depending on a active top item. But sometimes when the side menu item is clicked I have to show that items children instead of the sidemenu. When no children exist I just show Children of a top menu depending on the active item. I an really having difficulties implementing that kind a logic and any help would be appreciated. //Comment button is not working so I will add comments here After stumbling the zend navigation view helpers, I am coming to the point - Understanding the concept of how in zend V part of MVC is implemented can save someone who is new to the framework many hours. As said in the answer to this question - "Use what is available", thought first we have to know where to find what is already available out there - that is where comes handy to take a look at the concept of helpers and so forth.

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• Can I ask Postgresql to ignore errors within a transaction

  - by fmark

  I use Postgresql with the PostGIS extensions for ad-hoc spatial analysis. I generally construct and issue SQL queries by hand from within psql. I always wrap an analysis session within a transaction, so if I issue a destructive query I can roll it back. However, when I issue a query that contains an error, it cancels the transaction. Any further queries elicit the following warning: ERROR: current transaction is aborted, commands ignored until end of transaction block Is there a way I can turn this behaviour off? It is tiresome to rollback the transaction and rerun previous queries every time I make a typo.

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• Get highest frequency terms from Lucene index

  - by Julia

  Hello! i need to extract terms with highest frequencies from several lucene indexes, to use them for some semantic analysis. So, I want to get maybe top 30 most occuring terms(still did not decide on threshold, i will analyze results) and their per-index counts. I am aware that I might lose some precision because of potentionally dropped duplicates, but for now, lets say i am ok with that. So for the proposed solutions, (needless to say maybe) speed is not important, since I would do static analysis, I would put accent on simplicity of implementation because im not so skilled with Lucene (not the programming guru too :/ ) and cant wrap my mind around many concepts of it.. I can not find any code samples from something similar, so all concrete advices (code, pseudocode, links to code samples...) I will apretiate very much!!! Thank you!

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• Navigating cursor rows in SQLite

  - by Alan Harris-Reid

  Hi there, I am trying to understand how the following builtin functions work when sequentially processing cursor rows. The descriptions come from the Python 3.1 manual (using SQLite3) Cursor.fetchone() Fetches the next row of a query result set, returning a single sequence. Cursor.fetchmany() Fetches the next set of rows of a query result, returning a list. Cursor.fetchall() Fetches all (remaining) rows of a query result, returning a list. So if I have a loop in which I am processing one row at a time using cursor.fetchone(), and some later code requires that I return to the first row, or fetch all rows using fetchall(), how do I do it? The concept is a bit strange to me, especially coming from a Foxpro background which has the concept of a record pointer which can be moved to the 1st or last row in a cursor (go top/bottom), or go to the nth row (go n) Any help would be appreciated. Alan

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• how to exploit vulnerability of php?

  - by Dr Deo

  i have never seen a buffer overflow exploit in live action. supporse I have found a server that seems to have vulnerabilities. Where can i get proof of the concept code preferably in c/c++ to exploit the vulnerability? eg i found this vulnerability Multiple directory traversal vulnerabilities in functions such as 'posix_access()', 'chdir()', 'ftok()' may allow a remote attacker to bypass 'safe_mode' restrictions. (CVE-2008-2665 and CVE-2008-2666). How can i get proof of concept code for educational purposes PS I am a student and my only desire is to learn

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• JAAS tutorial - how to force application to run with policy

  - by wuntee

  I just went through this tutorial: http://java.sun.com/docs/books/tutorial/security/tour2/index.html And was curios about the basic concept of JAAS... If every applcation needs to be run with the '-Djava.security.manager -Djava.security.policy=...' flags, what is enforcing security? Is it up to the end user to know when any Java application is being run, and modify the executable/script/whatever to include those flags? Or, how does a developer enforce that an application is run with the security manager enabled? The whole concept doesnt seem very functional to me - as it is by default not enabled... Am I missing something?

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• What software analogies have helped you?

  - by Galwegian

  I have often enjoyed the use of analogies in understanding a software scenario or problem. For example, to understand the concept of public key encryption, the 'locked mailbox' analogy or similar is often used as an aid: An analogy for public-key encryption is that of a locked mailbox with a mail slot. The mail slot is exposed and accessible to the public; its location (the street address) is in essence the public key. Anyone knowing the street address can go to the door and drop a written message through the slot; however, only the person who possesses the key can open the mailbox and read the message. My question is: What analogies have you used or heard of in your career that have given you that "Eureka" moment with a complex concept? EDIT: If you have a good one, don't just state the name, please share with the group!

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• Local variables in java

  - by Mandar

  Hello , I went through local variables and class variables concept. But I had stuck at a doubt " Why is it so that we cannot declare local variables as static " ? For e.g Suppose we have a play( ) function : void play( ) { static int i=5; System.out.println(i); } It gives me error in eclipse : Illegal modifier for parameter i; I had this doubt because of the following concepts I have read : Variables inside method : scope is local i.e within that method. When variable is declared as static , it is present for the entire class i.e not to particular object. Please could anyone help me out to clarify the concept. Thanks.

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