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I'm using pyperplan in my project, however I'm very limited in choice of planning domains, as pyperplan does not support PDDL v2
Do you know of any pyperplan fork, that has this functionality? Basic +1 action costs should be enough, they are my only problem right now.
Eventually, do you know of any pyperplan-ish alternative that would support more modern versions of PDDL?
I'm planning to implement the functionality on my own, I ran through the code, and it shouldn't be THAT hard, it looks pretty set up for that.
I went through all forks listed on github, but none of them has this feature. I've also tried looking up such clone myself, or looking up any related articles, but nothing of value showed up.
I will be really grateful for any tips!
I'm real interested in using SubSonic, I've downloaded it and I'm enjoying it so far, but looking at the activity on github and googlegroups it doesn't seem to be very active and looks a lot like a project that's dying. There's no videos about it on tekpub and Rob seems to be using nHibernate for all his projects these days. I don't want to focus on learning SubSonic and integrating it into my projects if it's not going to live much longer.
So my question is what's happening with subsonic development, is there a new release imminent is there lots going on behind the scenes or is it as inactive as it seems?
I get this question, it seems, if I don't pop a release every 2 months or so. I will admit I'm behind on getting 3.0.0.4 out the door - but there's some patched code that people are sending in without tests and I will not accept that - I'd rather take my time and make sure we don't push bugs (which I apparently did with 3.0.0.3).
Anyway - it's a valid question and no, SubSonic isn't "dying". The best place to see the activity is on the Github site itself:
http://github.com/subsonic/
This is one of the main reasons I chose Github, so people can see the activity. I just pulled in a number of changes and am waiting on a last one to get tweaked (there were merge conflicts).
RE your other points:
No, I'm not using NHibernate for my work. I'm using it for Kona and a screencast. I answer just about all the email I get from out group but yes, GoogleGroups is a sad thing when it comes to pruning the spam. Your best bet is to just email the group list for a question - it will get answered pretty quickly.
In terms of "death" - I need to talk about that a bit. Open Source projects are incapable of dying if they were born in a fit of inspiration and people find it useful. Both are true of SubSonic. Even if I gave up and told everyone to f-off, someone would pick it up and run with it. I do have to work, like most people, and I have to fit SubSonic into the little amounts of freetime I have between work and family. But there's no way I'd let this die - it means far too much to me.
Either way - I'm sure I'll be back here again in 6 months, answering this question again :).
I suspect since its that time of year people are on holiday/vacation so support here is reduced. I have just started using it and havent had responses to some questions and the last release was in July, so am hoping support continues.
I must state that although there isn't a new release every 2 months as Rob stated that you may get that feeling sometimes. Although there is still action on the google group and github. If anything before christmas there were more fresh faces starting to make contributions than before (even simple ones like doco) this shows me that there may be more interest than ever, its just that people are getting on with it.
My work uses Subsonic (both 2.2 and 3.0.0.3) in most projects where we have control over it. We have around 28 .net devs and they all love it (we don't get caught up in what it can't do as its not an ORM/data access say per se.
As we only use Subsonic for low level query tool and not as a data access layer i spose we're not too closely connected to it if we need to bail on it, but we are yet to have a reason too.
My point is this: Its a really really easy to use, easy to pick up, easy to modify, light weight querytool/ORM(to a lesser extent). There are few tools out there that have all these properties and yet don't lock you into a million schools of thought on things. Because of this i don't see it dieing any time soon - its too addictive a tool to have on your bat belt.
I'm an active record fan buoy and SubSonic Rocksorz My Sockorz!
Because of this i recommend SubSonic to a lot of people and will continue to. While we don't use it on extremely large projects (more for project continuity reasons like you mentioned than because it can't do the job)
Well.
I don't know how subsonic is progressing. I started use subsonic from 2007, before upgrade to subsonic3, I was pretty convenient with subnoic2. it is stable and predictable. But with subsonic3, even 3.0.0.3. It is somewhat disappointed for me. I don't want to mention the features that works. Thanks. Subsonic map table correctly. The thing I want to talk is about "Update". I tried with the code but it gave exception. After dig into the code, it is signing...
Look at my code:
FarmDB db = new FarmDB();
db.Update<UserAdornment>().Set(o => o.is_working == false)
.Where(o => o.user_name == HttpContext.Current.User.Identity.Name && o.type == userAdornment.type && o.id != userAdornment.id).Execute();
Is this correct?
After fixed the NullReferenceException some one asked which I suffered too. Each time I run this query, all my rows with user_name=currentname is set is_working to false. After checked code:
In update.cs
public Update<T> Where(Expression<Func<T, bool>> column)
{
LambdaExpression lamda = column;
Constraint c = lamda.ParseConstraint();
And check lamda.ParseConstraint();
I see, whatever how many 'where" I want to search, it only return the first one, the worse thing is after it,
//IColumn col = tbl.GetColumnByPropertyName(c.ColumnName);
//Constraint con = new Constraint(c.Condition, col.Name, col.QualifiedName, col.Name);
//con.ParameterName = col.PropertyName;
//con.ParameterValue = c.ParameterValue;
It built another constraint from previous one, but drop all the "condition" in last one.
How can it be right?
I don't look into subsonic's sourcecode too much and don't understand it how it is implemented well. But I am using subsonic3 in my project and highly depend on it to work correctly. Really hope every bug can be tested and fixed in time.
I know this question seems subjective but it's really pretty simple. As a long term user, and part time contributor to SubSonic I'm interested in what the community thinks would be the single best way to improve it.
So what's your opinion, how would you make SubSonic even better? What one thing would make you more likely to use/recommend/evangelise/stop complaining about it?
As I said I know this is a bit subjective and may get closed but as SO is the main support forum for SubSonic I think this could be a useful way to solicit opinion and/or contributions.
To keep this from turning into a general discussion here's the rules:
No omnibus wishes
No duplicate wishes
Up-vote those you agree with rather than re-posting them
Ability to run in MediumTrust out of the box
In all honesty the biggest thing thats lacking is solid documentation and HowTo's
Its got better but I think it needs a lot more.
Ability to automatically map collections of other objects, like Fluent NHibernate does.
When SubSonic throws an exception that isn't clear, I'd like to be able to use Google or some other mechanism to discover more information about how to keep my development effort moving forward. Right now it's too easy to get into a situation where you have to go spelunking into the SubSonic source code since SubSonic doesn't seem to be very proactive when the user goes off the "happy path".
This critique is hardly specific to SubSonic. Many (most?) software products suffer from this same problem. I have not really had this problem with NHibernate though, which is SubSonic's most clear competitor.
Faster and higher quality releases
Binary types for SimpleRepository (Images)
Left Outer Joins
Support more database-independent code generation...
What I mean by this is that it is truly a real pain if your application wants to talk to different databases (e.g. SQL Server and Oracle) and you want to only have one set of generated DAL objects. I would love it if you had the option of specifying that any SQL code that gets sent to the DB would be as compatible with most engines as possible, since right now if you generated your objects targeting SQL Server then all queries will be of the form:
SELECT [schema].[table_name] FROM ....
Sadly, this does not work in Oracle, so basically you're out of luck there.
Perhaps this isn't a huge concern for most of you, but I'm currently writing a commercial app that touts one of its main features as being able to run on various database engines just by changing its configuration and I chose SubSonic because I thought it could handle the job pretty easily, but I'm honestly having second thoughts now because of all the hoops I may have to jump through just to get this to work correctly under different environments.
Support MS Access ,Postgres and FireBird database :)....
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I have always been astonished by Wine. Sometimes I want to hack on it, fix little things and generally understand how it works. So, I download the Wine source code and right after that I feel overwhelmed. The codebase is huge and - unlike the Linux Kernel - there are almost no guides about the code.
What are the best-practices for understanding such a huge codebase?
With a complex code base the biggest mistake you can make is trying to be a computer. Get the computer to run the code, and use a debugger to help find out what is going on.
Figure out how to compile, install and run your own version of Wine from the existing source code.
Learn how debug (e.g. use gdb) on a running instance of your version of Wine.
Run Wine under the debugger and make cause it to demonstrate the undesired behaviour.
The fun part: find where the code execution path goes and start learning how it all goes together.
Yes, reading lots and lots of code will help, but the compiler/debugger/computer can run code a lot faster than you.
A professor once told us to compare such a situation with climbing a mountain. You might be listening to someone who did this and tells you what it's like to look out into the country. And you believe without hesitation that that's a spectacular sight.
However, you have to start climbing yourself for real understanding what the view from the top is like.
And it's not that important to climb all the way to the top. It might be perfectly suficient just to reach a fair height above ground level.
But don't ever be afraid of start climbing. The view is always worth any efforts.
This has always been a nice analogy for me. I know this question was more about specific tips on how to efficiently deal with code bases once you started climbing. But nevertheless it instantly reminded me of our physics classes way back then.
(This is an answer I posted to a question a while back. I modified it a bit to fit this question.)
Experience has shown me that there are 3 major goals you have when learning a legacy system:
Learn what the code is supposed to do.
Learn how it does them.
(crucially) Learn why it does them the way it does.
All three of those parts are very important, and there's a few tricks to help you get started.
First, resist the temptation to just ctrl-click (or whatever your IDE uses) your way around the code to understand everything. You probably won't be able to keep everything in perspective in your mind this way, especially when each line forces you to look at multiple other classes in order to understand what it is, so you need to be able to hold several levels of the stack in your head.
Read documentation where possible; it usually helps you quickly gain a mental framework upon which to build everything that follows.
Run test cases where possible.
Don't be afraid to ask someone who knows if you have a question. Granted, you shouldn't waste others' time with inane queries, but if there's something that you simply don't understand (this is especially true with more conceptual questions like, "Wouldn't it make much more sense to implement this as a ___" or something), it's probably worth finding out the answer before you mess something up and don't know why.
When you do finally get down to reading the code, start at a logical "main" place and go from there. Don't just read the code top to bottom, or in alphabetical order, or anything (this is probably obvious).
The best way to get acquainted with a large codebase is to dive in. Many projects have a list of easy tasks that need to be done, and they're usually reserved to help ease people in. You should find and work on some of these; you'll learn a lot about the general code outline and structure, contribute to the project, and get an easy payoff that will help encourage you to take on larger tasks.
Like most projects, WINE has good resources available to its developers; IRC, wiki, mailing list, and guides/overviews. With most daunting codebases, it's not so scary after the first few fixes. WINE is truly large, and much like the kernel, I doubt there's any expert in all systems; don't feel like you need to be either. Start working on something that matters to you and take it from there.
I've started a few patches to WINE myself, and it's a good community and good structure. There's lots of very helpful debug messages, and it's a really cool project to work on, so that helps you hit it longer too.
We all appreciate your valor and willingness to help with WINE (it needs it). Thanks, and good luck.
Dig in. Think of a question you'd like to have answered, and try to find the answer. When you get tired of reading code, go read the dev mailing list, the developer's guide, or the wiki.
Unfortunately, there's no royal road to understanding a large code base. If you enjoy that sort of thing (I do) you're in for some fun. If not, guide books won't really help, so you aren't really that much worse off.
Look for one peculiar feature you are interested to improve. Search for its implementation. Once you found it, pull on that straw and all the rest will follow.
The best way is through comments.
I'm being ironic, as you understand tiny bits of the beast add comments so you can follow your trail.
The other developers will also enjoy it if you add the missing guides in the code.
Try to implement some tiny little change in the code, something that will be visible to you. That might be figuring out a workable way to output debugging statements (and figuring out where the output appears), it might be changing the default size of windows or desktop color, or something. Once you can make something happen in the codebase, you've scratched the surface of understanding and can begin to move on toward more complicated things. At that point, select a goal of something slightly more useful that you'd like the code to do, and implement that. Or check out the project's bug tracker and look for something small to start with.
Document as you go, and write unit tests as you go, and refactor as you go. When you figure out what a routine does, comment it!!
As others have suggested, dig in! Read all the available documentation you can absorb. Then see if you can find other people who are interested or knowledgeable and learn with/from them. It helps to have people to bounce ideas off of and ask questions.
For C source code, once you get a feel for what areas of the code you'd like to work on, generate ctags and cscope databases for that code. These tools make it a lot easier to jump around and understand the code. Many text editors (one example is gvim) have support for ctags and cscope so you can jump around easily.
(warning: shameless marketing ahead)
For Java developers using Eclipse, there's nWire. It is an Eclipse plugin for navigating and visualizing large codebases.
A good way to understand a large system is to break it down into it's constituent parts and focus on a specific paths through the application.
Your debugger is your friend here, set a breakpoint in the thread you want to investigate then step through it line by line looking at which each part does... hope that helps...
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I remember the old effective approach of studying a new framework. It was always the best way to read a good book on the subject, say MFC. When I tried to skip a lot of material to speed up coding it turned out later that it would be quicker to read the whole book first. There was no good ways to study a framework in small parts. Or at least I did not see them then.
The last years a lot of new things happened: improved search results from Google, programming blogs, much more people involved in Internet discussions, a lot of open source frameworks.
Right now when we write software we much often depend on third-party (usually open source) frameworks/ libraries. And a lot of times we need to know only a small amount of their functionality to use them. It's just about finding the simplest way of using a small subset of the library without unnecessary pessimizations.
What do you do to study as less as possible of the framework and still use it effectively?
For example, suppose you need to index a set of documents with Lucene. And you need to highlight search snippets. You don't care about stemmers, storing the index in one file vs. multiple files, fuzzy queries and a lot of other stuff that is going to occupy your brain if you study Lucene in depth.
So what are your strategies, approaches, tricks to save your time?
I will enumerate what I would do, though I feel that my process can be improved.
Search "lucene tutorial", "lucene highlight example" and so on. Try to estimate trust score of unofficial articles ( blog posts ) based on publishing date, the number and the tone of the comments. If there is no a definite answer - collect new search keywords and links on the target.
Search for really quick tutorials/ newbie guides on official site
Estimate how valuable are javadocs for a newbie. (Read Lucene highlight package summary)
Search for simple examples that come with a library, related to what you need. ( Study "src/demo/org/apache/lucene/demo")
Ask about "simple Lucene search highlighting example" in Lucene mail list. You can get no answer or even get a bad reputation if you ask a silly question. And often you don't know whether you question is silly because you have not studied the framework in depth.
Ask it on Stackoverflow or other QA service "could you give me a working example of search keywords highlighting in Lucene". However this question is very specific and can gain no answers or a bad score.
Estimate how easy to get the answer from the framework code if it's open sourced.
What are your study/ search routes? Write them in priority order if possible.
I use a three phase technique for evaluating APIs.
1) Discovery - In this phase I search StackOverflow, CodeProject, Google and Newsgroups with as many different combination of search phrases as possible and add everything that might fit my needs into a huge list.
2) Filter/Sort - For each item I found in my gathering phase I try to find out if it suits my needs. To do this I jump right into the API documentation and make sure it has all of the features I need. The results of this go into a weighted list with the best solutions at the top and all of the cruft filtered out.
3) Prototype - I take the top few contenders and try to do a small implementation hitting all of the important features. Whatever fits the project best here wins. If for some reason an issue comes up with the best choice during implementation, it's possible to fall back on other implementations.
Of course, a huge number of factors go into choosing the best API for the project. Some important ones:
How much will this increase the size of my distribution?
How well does the API fit with the style of my existing code?
Does it have high quality/any documentation?
Is it used by a lot of people?
How active is the community?
How active is the development team?
How responsive is the development team to bug patch requests?
Will the development team accept my patches?
Can I extend it to fit my needs?
How expensive will it be to implement overall?
... And of course many more. It's all very project dependent.
As to saving time, I would say trying to save too much here will just come back to bite you later. The time put into selecting a good library is at least as important as the time spent implementing it. Also, think down the road, in six months would you rather be happily coding or would you rather be arguing with a xenophobic dev team :). Spending a couple of extra days now doing a thorough evaluation of your choices can save a lot of pain later.
The answer to your question depends on where you fall on the continuum of generality/specificity. Do you want to solve an immediate problem? Are you looking to develop a deep understanding of the library? Chances are you’re somewhere between those extremes. Jeff Atwood has a post about how programmers move between these levels, based on their need.
When first getting started, read something on the high-level design of the framework or library (or language, or whatever technology it is), preferably by one of the designers. Try to determine what problems they are trying to address, what the organizing principles behind the design are, and what the central features are. This will form the conceptual framework from which future understanding will hang.
Now jump in to it. Create something. Do not copy and paste somebody's code. Instead, when things don’t work, read the error messages in detail, and the help on those error messages, and figure out why that error occurred. It can be frustrating, when things don’t work, but it forces you to think, and that’s when you learn.
1) Search Google for my task
2) look at examples with a few different libraries, no need to tie myself down to Lucene for example, if I don't know what other options I have.
3) Look at the date of last update on the main page, if it hasn't been updated in 6-months leave (with some exceptions)
4) Search for sample task with library (don't read tutorials yet)
5) Can I understand what's going on without a tutorial? If yes continue if no start back at 1
6) Try to implement the task
7) Watch myself fail
8) Read a tutorial
9) Try to implement the task
10) Watch myself fail and ask on StackOverflow, or mail the authors, post on user group (if friendly looking)
11) If I could get the task done, I'll consider the framework worthy of study and read up the main tutorial for 2 hours (if it doesn't fit in 2 hours I just ignore what's left until I need it)
I have no recipe, in the sense of a set of steps I always follow, that's largely because everything I learn is different. Some things are radically new to me (Dojo for example, I have no fluency in Java script so that's a big task), some just enhancements of previous knowledge (Iknow EJB 2 well, so learning EJB 3 while on the surface is new with all its annotations, its building on concepts.)
My general strategy though is I'd describe as "Spiral and Park". I try to circle the landscape first, understand the general shape, I Park concepts that I don't get just yet, don't let it worry me. Then i go a little deeper into some areas, but again try not to get obsessed with one, Spiralling down into the subject. Hopefully I start to unpark and understand, but also need to park more things.
Initially I want answers to questions such as:
What's it for?
Why would I use this rather than that other thing I already know
What's possible? Any interesting sweet spots. "Eg. ooh look at that nice AJAX-driven update"
I do a great deal of skim reading.
Then I want to do more exploring on the hows. I start to look for gotchas and good advice. (Eg. in java: why is "wibble".equals(var) a useful construct?)
Specific techniques and information sources:
Most important: doing! As early as possible I want to work a tutorial or two. I probably have to get the first circuit of the spiral done, but then I want to touch and experiment.
Overview documents
Product documents
Forums and discussion groups, learning by answering questions is my favourite technique.
if at all possible I try to find gurus. I'm fortunate in having in my immediate colleagues a wealth of knowledge and experience.
Quick-start guides.
A quick look at the API documentation if available.
Reading sample codes.
Messing around YOU HAVE TO MESS AROUND (sorry for the caps).
If it's a small library/API with a small or no community you can always contact the developer himself and ask for help 'cause he'll probably be more than happy to help you; he's happy that one more person is using his API.
Mailing lists are a great resource as long as you do your homework first before asking questions.
Mailing list archives are invaluable for most of the questions I've had on CoreAudio related stuff.
I would never read javadoc. As there often is none. And when there is, most likely it isnt up to date. So one gets confused at the best.
Start with the simplest possible tutorial you find within some minutes.
Often the tutorial will lead you to further sources at the end, so then most of the time one is on a path that goes on and on, deeper and deeper.
It really depends on what the topic is and how much info is on it. Learning by example is a good way to start a topic brand new to you, especially if you're knowledgeable in other similar libraries or languages. You can take a topic you're familiar with, and say "I understand how to implement using X, lets see how it's done using Y".
So what are your strategies, approaches, tricks to save your time?
Well, I search. I generally never ask questions, preferring to research myself. If worse comes to worse I'll read the documentation. In some cases (say, when I was doing some work with SharpSVN) I had to look at the source, specifically the test cases, to get some information about how the API worked.
Generally, I have to be honest, most of my 'study' and 'learning' is by accident.
For example, just a few seconds ago, I discovered how to get the "Recent" folder in C#. I had no idea how to do that before seeing the question, considering it interesting, and then searching.
So for me the real 'trick' is that I hang around on forums, answer questions, and accidentally pick up knowledge. Then when it comes time for me to research something; chances are I know a bit about it, and searching is easier and I can focus on the implementation [typically implementing a test program first] and progressing from there.