I need to dive into KML, so I'm looking at specs and examples on the web, but I get some inconsistent information.
For instance, some sites say you write things like <tessellate>true</tessellate> while others have <tessellate>1</tessellate>, and yet others say tessellate isn't necessary any more, since altitudeMode provides the same information.
So I've got a lot of little questions, such as which is safer here, 1/0 or true/false. And what is KML the abbreviation of, Keyhole Markup Language or Keyhole Modelling Language?
But my question basically is, where do I find the standard, the authoritative and definitive reference for KML? Then I can ignore the other sources.
http://code.google.com/apis/kml/documentation/kmlreference.html
Should probably be considered the primary reference. That's the one I always refer to.
It include Google specific extensions (prefixed by gx:) which you can choose to ignore (or not).
Although
http://www.opengeospatial.org/standards/kml/
is the real definitive source, its nowhere near as accessible as the Google one (which preceded OGC taking on KML) - I dont even know how to read the OGC one!
KML used to represent "Keyhole Markup Language"
Boolean, is probably best considered 1/0 - some clients might understand true etc, but for maximum compatiblity go with 1/0
btw, tessellate is useful in itself, it does not do the same as altitudeMode. They complement each other.
Related
Our users can enter questions that get answered by students. Our users need a extensible, flexible way to define the correct answers to these questions (which are stored as a simple string).
I would like to expose a library of domain specific functions that users can call on to describe the correct answer. Eg:
exact_match("puppy") // means the correct answer is the string 'puppy'
or
contains("yesterday") // means any answer with the word 'yesterday' is correct
The naive implementation would involve eval'ing user supplied strings in a sandboxed runtime (like a javascript vm or ruby vm). But I'd like to go further and only allow specific functions to be called. Any other scripting would be discarded. Such that:
puts("foo"); contains("yesterday")
would be illegal. Since we don't expose or allow puts().
How can I constrain the execution environment to only run a whitelist of functions? Or is there a different approach to build this kind of external-facing DSL instead of trying to constrain an existing language to a subset of functions?
I would check out MPS by JetBrains if I were you, its an open source DSL creation tool. I have never used it myself, but from everything I have seen on it, it's very intuitive; and all of their other products are incredibly powerful.
Just because you're creating a DSL, that doesn't necessarily mean that you have to give the user the ability to enter the code in text.
The key to this is providing a list of method names and your special keyword for them, the "FunCode" tag in the code example below:
Create a mapping from keyword to code, and letting them define everything they need, and then use it. And I would actually build my own XML parser so that it's not hackable, at least not on a list of zero-day-exploits hackable.
<strDefs>
<strDef><strNam>sickStr</strNam>
<strText>sick</strText><strNum>01</strNum><strDef>
<strDef><strNam>pupStr</strNam>
<strText>puppy</strText><strNum>02</strNum><strDef>
</strDefs>
<funDefs>
<funDef><funCode>pfContainsStr</funCode><funLabel>contains</funLabel>
<funNum>01</funNum></funDef>
<funDef><funCode>pfXact</funCode><funLabel>exact_match</funLabel>
<funNum>02</funNum></funDef>
</funDefs>
<queries>
<query><fun>01</fun><str>02</str>
</query>
</queries>
The above XML more represents the idea and the structure of what to do, but rather in a user interface, so the user is constrained. The user interface code that allows the data-entry of the above data should be running on your server, and they only interact with it. Any code that runs on their browser is hackable, because they can just save the page, edit the HTML (and/or JavaScript), and run that, which is their code now, not yours anymore.
You can't really open the door (pandora's box) and allow just anyone to write just any code and have it evaluated / interpreted by the language parser, because some hacker is going to exploit it. You must lock down the strings, probably by having them enter them into your database in an earlier step, and each string gets its own token that YOU generate (a SQL Server primary key is very simple, usable, and secure), but give them a display representation so it's readable to them.
Then give them a list of methods / functions they can use, along with a token (a primary key can also serve here, perhaps with a kind of table prefix) and also a display representation (label).
If you have them put all of their labels into yet another table, you can have SQL make sure that all of their labels are unique to each other in the whole "language", and then you can allow them to try to define their expressions in the language they want to use. This has the advantage that foreign languages can be used, but you don't have to do anything terribly special.
An important piece would be the verify button, that would translate their expression into unique tokens and back again, checking that the round-trip was successful. If it wasn't successful, there's some kind of ambiguity, and you might be able to allow them an option to use the list of tokens as the source in that case.
If you heavily rely on set-based logic for the underlying foundation of the language and your tables, you should be able to produce a coherent DSL that works. Many DSL creation problems are ones of integrity, where there are underlying assumptions that are contradictory, unintentionally mutually exclusive, or nonsensical. Truth is an unshakeable foundation. Anything else has a lie somewhere -- that you're trying to build on.
Sudoku is illustrative here. When you screw up a Sudoku, you often don't know that you have done so, and you keep building on that false foundation, until you get to the completion of the puzzle, and one whole string of assumptions disagrees with a different string of assumptions. They can't both be true. But you can't tell where you went wrong because you're too far away from the mistake and can not work backwards (easily). All steps taken look correct. A DSL, a database schema, and code, are all this way. Baby steps, that are double- and even triple-checked, and hopefully "correct by inspection", are the best way to "grow" a DSL, slowly, piece-by-piece. The best way to not have flaws is to not add them in the first place.
You don't want bugs in your DSL. Keep it spartan. KISS - Keep it simple, Sparticus! And I have personally found that keeping it set-based, if not overtly, under the covers, accomplishes this very well.
Finally, to be able to think this way, I've studied languages for a long time, and have cultivated a curiosity about how languages have come to be. Books are a good quality source of information, as they have a higher quality level than the internet, which is nevertheless also an indispensable source. Some of my favorite languages: Forth, Factor, SETL, F#, C#, Visual FoxPro (especially for its embedded SQL), T-SQL, Common LISP, Clojure, and probably my favorite, Dylan, an INFIX Lisp without parentheses that Apple experimented with and abandoned, with a syntax that seems to me reminiscent of Pascal, which I sort of liked. The language list is actually much longer than that (and I haven't written code for many of them -- just studied them or their genesis), but that's enough for now.
One of my favorite books, and immensely interesting for the "people" side of it, is "Masterminds of Programming: Conversations with the Creators of Major Programming Languages" (Theory in Practice (O'Reilly)) 1st Edition, Kindle Edition
by Federico Biancuzzi (Author), Chromatic (Author)
By the way, don't let them compromise the integrity of your DSL -- require that it is expressible set-based, and things should go well (IMHO). I hope it works out well for you. Add a comment to my answer telling me how it worked out, if you think of it. And don't forget to choose my answer if you think it's the best! We work hard for the money! ;-)
Does one of you know where to find statistics on websites using web standards?
I've read multiple books on web standards, all give very unspecific data on how many sites comply to web standards.
Books like "designing with web standards", "CSS Mastery", "HTML and web standards solutions" all contain definitions like "some", "more and more" and "not nearly enough" without a source for this data.
Of course I realise there won't be an exact number, an indication would be great. I feel like those writers will need to have gotten their data from somewhere.
I would be great if any of you could point me in the right direction.
There's a very good reason that those books you read only provided indeterminate quantities like "some", "more", and "not nearly enough". It's because this type of data is not easily obtainable, not by the authors nor by us on Stack Overflow. Anything you might find would be idle speculation at best, and more likely tainted by some strong personal biases.
Those writers did get their data from somewhere, but I can't provide any more detail because this is a family-friendly site. Scott Adams used a similar theme to great success in one of his famous comics:
Fortunately, even if you were able to find this data, it wouldn't be particularly relevant. The decision to comply or not to comply with web standards should not be made based on what everyone else is doing.
As has been mentioned, there won't be any such list available. However, I believe most web developers / designers would have a good 'feel' for how many sites they've looked at conform to all standards - and my hunch would be this number would be pretty low (based on my personal experience).
If you are really keen on figures, maybe take the top 100 websites on the web and go validate them all. Shouldn't take too long and you'd get a feel for how many conform to at least basic valid (X)HTML standards.
Since all the browsers don't actually follow the standards in the same way, this leads to websites being forced to use non-standard code to ensure a consistent feature set and look and feel. The situation has improved massively in recent years but is still far from ideal.
You also have the problem that even agreeing on what the standards are can take a very long time let alone waiting for everyone to comply. The current pace of development of modern browsers means standards will always be playing catch up somewhat.
Sites such as validator.w3.org, quirksmode.org, acid3.acidtests.org, html5test.com are great to keep up with the latest cross browser techniques and browser support but attempting to code a website and strictly remain inside a set of out dated rigid standards appears a zero sum game.
I need to find figures that show how many programmers world wide, has each of the following languages as their primary programming language.
C
C++
C#
Object-C
Java
JavaScript
VB.NET
VB6 (or older)
VBA
PHP
flash scripts
Ruby
Does anyone know of such comparison figures?
If not. Do you know of a good way to research this?
I could compare the number of tags here at stackoverflow and the number of articles for each language at sites like codeproject. This would give me a good idea.
But if you can suggest other ideas how to find these numbers I will be greatfull.
/Thomas
A very common site that does this is the TIOBE index. It basically searches for programming languages in major search engines and compares the results, and it shows you some history. The only problem is that C/C++/C# are not distinguished very well, therefore C is more dominant than you'd expect (not to mention that search results include many pages where many languages are listed, like programming FAQs). But in general, TIOBE gives a good idea, I think, and it should get better, since at least Google tends to know the difference between zero, two or four pluses.
Have you tried TIOBE index?
In general this is hard to measure because every approach has a lot of drawbacks.
TIOBE and others that are based on search results e.g. do not tell anything of what is actually used but just what is highly ranked by google (You can even see that just Google changing a bit of their results in 2004/2005 completely mixed TIOBE). And moreover they have the problem that lots of search-terms are ambiguous (Like Java which IS also an island, Ruby which also exists as gem, Python which is a snake and others which have alternative meaning). Another problem with search based is that most things put into the web stay up forever which means it is irrelevant if it is CURRENTLY interesting. If a C resource was put up in 2002 it likely still is available today (which hugely overrates leading or older languages.)
Here one is an interesting approach based on the number of book sales. (This at least eliminates the ambigous problem, but comes with others.)
Wikipedia also has a small article about the topic.
Try Google trends (see an example). In addition, check sites like freshmeat.net and note the number of projects in each language. That's only open source projects and many people will use a different language for their hobby projects than at work (i.e. one that sucks less).
Next, look for sites which offer job openings. I don't have a good link handy but this Google query should get your started.
not yet!!!!!!!
That's only open source projects and many people will use a different language for their hobby projects than at work (i.e. one that sucks less).
Next, look for sites which offer job openings. I don't have a good link handy but this Google query should get your started.
The title may seem slightly self-contradictory, and I accept that you can't really learn a language quickly. However, an experienced programmer that already has knowledge of a few languagues and different styles (functional, OO, imperative etc.) often wants to get started quickly. I've seen a few websites doing effective "translations" in the form of "just show me syntax equivalence". I can't remember the sites now, but for related languages (e.g. Perl/PHP) it's quite common.
Is there a better resource that covers more languages? Is there a resource that covers idioms as well as syntax? I think this would be incredibly useful for doing small amounts of work on existing code bases where you are not familiar with the language. Looking at the existing code, as we know, is not always a good indicator of quality. Likewise, for "learn by doing" weekend project I always have the urge to write reasonably idiomatic, clean code from the start. Such a resource could also link to known good example projects of varying sizes for those that prefer to learn by reading. Reading a well-written medium sized code base can also be much more practical when access to development environments might be limited.
I think it's possible to find tutorials and summaries for individual languages that provide some of this functionality in disparate web locations but I'm hoping there is a good, centralised, comparative place that the busy programmer can turn to.
You generally have two main things to overcome:
Syntax
Reference
Syntax you can pick up fairly quickly with a language tutorial and a stack of samplecode.
Reference (library/API calls) you need to find a proper guide to; perhaps the language reference, or perhaps google...
With those two in place, following a walkthrough (to get you used to using the development environment) will have you pretty much ready - you'll be able to look up what you want to say (reference), and know how to say it (syntax).
This, of course, applies principally to procedural/oop languages; languages that require a paradigm switch (ML/Haskell) you should go to lectures for ;)
(and for the weirder moments, there's SO!)
In the past my favour was "learning by doing". So e.g. I know a little bit of C++ and a lot of C#.Net but I must write a FTP Tool in Python.
So I sit for an hour and so the syntax differences by a tutorial, than I develop the form itself and look at the generated code. Then I search a open source Python FTP Client and get pieces of code (Not copy and paste, write it self to see, feel and remember the code!)
After a few hours I get it.
So: The mix is the best. A book, a piece of good code, the willing to learn and a free night with much coffee.
At the risk of sounding cheesy, I would start with the language's website tutorial and/or FAQ, followed by asking more specific questions here. SO is my centralized location for programming knowledge.
I remember when I learned Perl. I was asked to modify some Perl code at work and I'd never seen the language before. I had experience with several other languages, however, so it wasn't hard to figure out the syntax with the online Perl docs in one window and the code in another, side-by-side. I don't know that solely reading existing code is necessarily the best way to learn. In my case, I didn't know Perl but I could tell that the person who originally wrote the code didn't know Perl either. I'm not sure I could've distinguished between good Perl and really confusing Perl. It would've been nice to be able to ask questions here at the time.
Language isn't important. What is important is learning your ways around designing algorithms and the proper application of design patterns. Focus on the technique, not the language that implements a certain technique. Once you understand the proper development techniques, any programming language will just become real easy, no matter how obscure they are...
When you put a focus on a language, you're restricting your own knowledge.
http://devcheatsheet.com/ seems to be a step in the right direction: it aggregates cheat sheets/quick references and they are (somewhat) manually reviewed. It's also wide-ranging. It still comes up short a bit in terms of "idiomatic" quick reference: for example, the page on Ruby doesn't mention yield.
Rosetta Code appears to be an excellent resource that includes hints on coding idiomatically and moves from simple (like for-loops) to things like drawing. I haven't checked out how comprehensive it is, but there are a large number of languages and tasks listed. The drawbacks re: original question are:
Some of the linking is not accurate
(navigating Python->ForLoop will
take you to the top of the ForLoop
page, not the Python section). It's a
wiki, this can be improved.
Ideally you could "slice" the wiki
however you chose to see e.g. the top
20 tasks for two languages
side-by-side.
http://hyperpolyglot.org/ seems to be an almost perfect match for what I was looking for. The quality is not always there, or idiom can be lacking, but it has the same intention and is pretty comprehensive.
I flatter myself that I'm a good programmer, and can get away with graphic design. But something I'm incapable of doing is coming up with good names - and it seems neither are the people I work with. We're now in the slightly ludicrous situation that the product we've been working on for a couple of years is being installed to customers, is well received and is making money - but doesn't yet have a name.
We're too small a company to have anything like a proper marketing division to do this thing. So how have people tended to choose names, logos and branding?
When it's for something that "matters", I plop down the $50 and have the folks at PickyDomains.com help out. That also results in a name that's available as a .com.
For guidelines, here's an extract from my own guide on naming open source projects:
If the name you're thinking of is directly pulled from a scifi or fantasy source, don't bother. These sources are WAY overrepresented as naming sources in software. Not only are your chances of coming up with something original pretty small, most of the names of characters and places in scifi are trademarked and you run the risk of being sued.
If the name you're thinking of comes straight from Greek, Roman or Norse mythology, try again. We've got more than enough mail related software called variations of "Mercury".
Run your proposed name through Google. The fewer results you get the better. If you get down to no results, you're there.
Don't try to get a unique name by just slightly misspelling something. Calling your new Windows filesystem program Phat32 is just going to end up with users getting frustrated looking at the results of "fat32" in a search engine.
If your name couldn't be said on TV in the 50s or 60s, you're probably on the wrong track. This is particularly true if you would like anyone to use your product in a work environment. No one is going to recommend a product to their co-workers if they can get sued for sexual harassment just for uttering its name.
If your product name can't be pronounced at all, you'll get no word of mouth benefit at all. Similarly, if no one knows how to pronounce it, they will not be very likely to try to say it out loud to ask questions about it, etc. How do YOU say MySQL? PostgreSQL? GNU? Almost all spoken languages on Earth are based on consonant/vowel syllables of some sort. Alternating between consonants and vowels is a pretty good way to ensure that someone can pronounce it.
The shorter the better.
See if the .com domain is available. If it's not, it's a pretty good indicator that someone has already thought of it and is using it or closer to using it than you are. Do this even if you don't intend to use the domain.
Don't build inherent limitations on your product into the name. Calling your product LinProduct or WinProduct precludes you from ever releasing any sort of cross-platform edition.
Don't use your own name for open source products. If the project lives on beyond your involvement, the project will either have to be renamed or your name may be used in ways you didn't intend.
for a product, first read Positioning, the Battle for Your Mind and think really hard about what mental position you want to occupy
then find a word or two that conveys that position, and make up an acronym for it
for a (self-serving) example: my most recent product is a fine-grained application monitor for .NET applications. I want to convey the feeling of peace that you have when you know that your apps are behaving because they are continuously monitored, so 'no news' really is 'good news'. I chose CALM after a lot of false starts, and decided that it stood for Common Application Lightweight Monitor - which just also happens to be a very technically accurate description of the basic implementation
also, you might be amazed at how much 'better' users perceive an application to be when it has a name and a logo attached to it.
You should try BustaName. It basically combines words to create available domain names. You are able to choose similar words for the words that you previously entered.
Also try these links out:
Naming a company
77 ways to come up with an idea
Igor Naming Guide (PDF)
Names -- you can try yourselves or ask friends/customers about what they are thinking about when listen/use your product (I don't know correct English word for that -- if two things have something in common they are associated?).
Or, depends on what kind of product is it, ask someone with unlimited imagination -- kids are very good at it.
Logos and branding -- you need professionals.
And of course you need layer :).
I second the recommendation of the Igor naming guide. Stay away from meaningless strings of alternating vowels and consonants: altana, obito, temora, even if it seems easy and the domains are readily available. Pick something with soul and meaning. Best example: "Plan B" (also known as the morning-after pill).