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• Should programming languages be strict or loose?

  - by Ralph

  In Python and JavaScript, semi-colons are optional. In PHP, quotes around array-keys are optional ($_GET[key] vs $_GET['key']), although if you omit them it will first look for a constant by that name. It also allows 2 different styles for blocks (colon, or brace delimited). I'm creating a programming language now, and I'm trying to decide how strict I should make it. There are a lot of cases where extra characters aren't really necessary and can be unambiguously interpreted due to priorities, but I'm wondering if I should still enforce them or not to encourage good programming habits. What do you think?

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• n00b needs some PHP syntax guidance [closed]

  - by Michael

  If you look at http://www.cruc.es/?paged=12/ and go to the bottom of the page you'll see the bottom navigation with the next and previous options. I've been able to make the page numbers work by changing page to paged= in the code. I don't know enough about PHP to get the previous/next options to work. Any advice would be appreciated and I've pasted the code below. Thank you: n00b if ( $query->found_posts > $query->query_vars["posts_per_page"] ) { echo '<ul class="paging">'; // Previous link? if ( $page > 1 ) { echo '<li class="previous"><a href="'.$baseURL.'/page/'.($page-1).'/'.$qs.'">previous</a></li>'; } // Loop through pages for ( $i=1; $i <= $query->max_num_pages; $i++ ) { // Current page or linked page? if ( $i == $page ) { echo '<li class="active">'.$i.'</li>'; } else { echo '<li><a href="'.$baseURL.'/?paged='.$i.'/'.$qs.'">'.$i.'</a></li>'; } } // Next link? if ( $page < $query->max_num_pages ) { echo '<li><a href="'.$baseURL.'/page/'.($page+1).'/'.$qs.'">next</a></li>'; } echo '</ul>'; }

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• What defines a language as a scripting language? [closed]

  - by Mathew Foscarini

  Possible Duplicate: What is the main difference between Scripting Languages and Programming Languages? I'd like to know what defines a language as a scripting language compared against other programming languages. Some possible scripting languages might include AutoCad LISP, Linux Bash, DOS Batch, Javascript or ActionScript in Flash. Where is the distinction made that makes a language a scripting language? Are there a set of clearly define rules to classify it as such?

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• Is `break` and `continue` bad programming practice?

  - by Mikhail

  My boss keeps mentioning nonchalantly that bad programmers use break and continue in loops. I use them all the time because they make sense; let me show you the inspiration: function verify(object) { if (object->value < 0) return false; if (object->value > object->max_value) return false; if (object->name == "") return false; ... } The point here is that first the function checks that the conditions are correct, then executes the actual functionality. IMO same applies with loops: while (primary_condition) { if (loop_count > 1000) break; if (time_exect > 3600) break; if (this->data == "undefined") continue; if (this->skip == true) continue; ... } I think this makes it easier to read & debug; but I also don't see a downside. Please comment.

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• Kernel error during upgrade due to "/etc/default/grub: Syntax error: newline unexpected"

  - by Patrick - Developer

  Summary: linux-image-3.5.0-2-generic upgrade to linux-image-3.5.0-3-generic The default Ubuntu 12.04 update is generating the following error for weeks (the link below). Obs.: I'm using default update of Ubuntu 12.04 ie, apt-get update. log error: https://gist.github.com/3036775 Overall he is trying to do the following: upgrade the "linux-image-3.5.0-2-generic upgrade to linux-image-3.5.0-3-generic" and the error always, always. What to do?

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• Random MongoDb Syntax: Updates

  - by Liam McLennan

  I have a MongoDb collection called tweets. Each document has a property system_classification. If the value of system_classification is ‘+’ I want to change it to ‘positive’. For a regular relational database the query would be: update tweets set system_classification = 'positive' where system_classification = '+' the MongoDb equivalent is: db.tweets.update({system_classification: '+'}, {$set: {system_classification:'positive'}}, false, true) Parameter Description { system_classification: '+' } the first parameter identifies the documents to select { $set: { system_classification: 'positive' } } the second parameter is an operation ($set) and the parameter to that operation {system_classification: ‘positive’} false the third parameter indicates if this is a regular update or an upsert (true for upsert) true the final parameter indicates if the operation should be applied to all selected documents (or just the first)

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• How are "Json.org"-like specs graphs called and how can I generate them?

  - by Sebastián Grignoli

  In http://www.json.org Douglas Crockford shows the specs of the JSON format in two interesting ways: In the right side column he lists a text spec that looks like a YACC or LEX listing. In the main body of the homepage, he put several images that gives us a simple way to visually understand the valid sequences that composes a JSON string. Those images look like a description of the path that a finite state automaton would follow when parsing the JSON string. Wich are the names (if any) of that listing format and that kind of graphics? Is there any software that renders a source file containing the specification into that kind of images?

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• Preferred lambda syntax?

  - by Roger Alsing

  I'm playing around a bit with my own C like DSL grammar and would like some oppinions. I've reserved the use of "(...)" for invocations. eg: foo(1,2); My grammar supports "trailing closures" , pretty much like Ruby's blocks that can be passed as the last argument of an invocation. Currently my grammar support trailing closures like this: foo(1,2) { //parameterless closure passed as the last argument to foo } or foo(1,2) [x] { //closure with one argument (x) passed as the last argument to foo print (x); } The reason why I use [args] instead of (args) is that (args) is ambigious: foo(1,2) (x) { } There is no way in this case to tell if foo expects 3 arguments (int,int,closure(x)) or if foo expects 2 arguments and returns a closure with one argument(int,int) - closure(x) So thats pretty much the reason why I use [] as for now. I could change this to something like: foo(1,2) : (x) { } or foo(1,2) (x) -> { } So the actual question is, what do you think looks best? [...] is somewhat wrist unfriendly. let x = [a,b] { } Ideas?

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• How to programmatically construct textual query

  - by stibi

  Here is a query language, more specifically, it's JQL, you can use it in Jira, to search for issues, it's something like SQL, but quite simpler. My case is that, I need to construct such queries programmatically, in my application. Something like: JQLMachine jqlMachine = new JQLMachine() jqlMachine.setStatuses("Open", "In Progress") jqlMachine.setReporter("foouser", "baruser") jqlMachine.setDateRange(...) jqlMachine.getQuery() --> String with corresponding JQL query is returned You get my point I hope. I can imagine the code for this, but it's not nice, using my current knowledge how I'd do that. That's why I'm asking. What you'd advice to use to create such thing. I believe some patterns for creating something like this already exist and there is already best practices, how to do that in good way.

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• Expressions that are idiomatic in one language but not used or impossible in another

  - by Tungsten

  I often find myself working in unfamiliar languages. I like to read code written by others and then jump in and write something myself before going back and learning the corners of each language. To speed up this process, it really helps to know a few of the idioms you'll encounter ahead of time. Some of these, I've found are fairly unique. In Python you might do something like this: '\n'.join(listOfThings) Not all languages allow you to call methods on string literals like this. In C, you can write a loop like this: int i = 50; while(i--) { /* do something 50 times */ } C lets you decrement in the loop condition expression. Most more modern languages disallow this. Do you have any other good examples? I'm interested in often used constructions not odd corner cases.

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• apache2 server returns (400) syntax error

  - by Thomas E

  There are 900 paths in the googles index to our homepage containing illegal characters. Example: http://www.seriesam.com/filmaffisch/TC%4NK Note the character "%4N". I have no idea where they come from, but would like to update google index with a correct URL using "canonical" in the html code. But the problem is our apache2 server immediately sends a 400 error if you click the link above. How can I configure apache2 not to give an error code, but instead treat the link above as "correct"? Maybe replacing the char %4N with nothing.

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• MySQL: operation of summing and division ?

  - by Nick

  Alright, so I have a user table and would like to get the max value for the user with the highest amount of points divided by a score. Below is a rough idea of what I'm looking for: SELECT MAX(SUM(points)/SUM(score)) FROM users I'm not interested in adding up both columns and dividing, rather I'm interested in dividing the points and score for each user and retrieve the highest value out of the lot.

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• Why the Select is before the From in a SQL Query?

  - by Scorpi0

  This is something that bothered me a lot at school. 5 years ago, when I learned SQL, I always wondered why we specify first the fields we want and then where we want them from. According to my idea, we should write: From Employee e Select e.Name So why the norm says: Select e.Name -- Eeeeek, what e means ? From Employee e -- Ok, now I know what e is It took me weeks to understand SQL, and I know that a lot of that time was consumed by the wrong order of elements. It is like writing in C#: string name = employee.Name; var employee = this.GetEmployee(); So, I assume that it has a historical reason, anyone knows why?

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• LAG function – practical use and comparison to old syntax

  - by Michael Zilberstein

  Recently I had to analyze huge trace – 46GB of trc files. Looping over files I loaded them into trace table using fn_trace_gettable function and filters I could use in order to filter out irrelevant data. I ended up with 6.5 million rows table, total of 7.4GB in size. It contained RowNum column which was defined as identity, primary key, clustered. One of the first things I detected was that although time difference between first and last events in the trace was 10 hours, total duration of all sql...(read more)

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• LAG function – practical use and comparison to old syntax

  - by Michael Zilberstein

  Recently I had to analyze huge trace – 46GB of trc files. Looping over files I loaded them into trace table using fn_trace_gettable function and filters I could use in order to filter out irrelevant data. I ended up with 6.5 million rows table, total of 7.4GB in size. It contained RowNum column which was defined as identity, primary key, clustered. One of the first things I detected was that although time difference between first and last events in the trace was 10 hours, total duration of all sql...(read more)

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• How to sum and divide in MySql [migrated]

  - by Nick

  Alright, so I have a user table and would like to get the max value for the user with the highest amount of points divided by a score. Below is a rough idea of what I'm looking for: SELECT MAX(SUM(points)/SUM(score)) FROM users I'm not interested in adding up both columns and dividing, rather I'm interested in dividing the points and score for each user and retrieve the highest value out of the lot.

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• Do you use i-->0 for backward loops?

  - by maaartinus

  Some people write for (int i=N; i-->0; ) doSomething(i); instead of for (int i=N-1; i>=0; --i) doSomething(i); for backward loops. The --> "operator"1 looks very confusing at the first glance, but it's trivial: i-->0 simply parses as (i--)>0, and once you get it, you see it immediately. The main disadvantage is the strange look. The advantage is that you'll get it always right (unlike the more verbose version offering the possibility to forget something, which really happened to me a couple of times). What do you think about using the --> "operator"? 1First time I saw the funny term in a comment to this question today.

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• What's the point of initializing a variable with the same value twice?

  - by JoeM05

  I was reading Ben Cherry's "JavaScript Module Pattern: In-Depth", and he had some example code that I didn't quite understand. Under the Cross-File Private State heading, there is some example code that has the following: var _private = my._private = my._private || {} This doesn't seem to be different from writing something like this: var _private = my._private || {} What's happening here and how are these two declarations different?

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• Are "backwards" terminators for if and case unique to shell scripting?

  - by tomjakubowski

  In bash at least, if and case blocks are closed like this: if some-expr then echo "hello world" fi case $some-var in [1-5]) do-a-thing ;; *) do-another-thing esac as opposed to the more typical close of end or endif/endcase. As far as I know, this rather funny convention is unique to shell scripting and I have never seen such an odd block terminator anywhere else. Sometimes things like this have an origin in another language (like Ruby's elsif coming from Perl), or a strange justification. Does this feature of shell scripting have a story behind it? Is it found in other languages?

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• Would you see any use of a Trilean (True, False, ??)

  - by Sybiam

  I don't know if I'm alone but sometimes I have a function that should return true or false. But in some case there would be a third result that would make more sense. In some language theses cases would be handled with integers or with exception. For exemple you want to handle the age of a user if he is over 18 years old. And you have a function like this. if(user.isAdult(country_code)){ //Go On }else{ // Block access or do nothing } But in some case depending how your app is built I could see case where the birthday field is incomplete. Then this function should return something undetermined. switch(user.isAdult()){ case true: // go on break; case undetermined: //Inform user birthday is incomplete case false: //Block access } As i said we can handle that with Exceptions and Int, but I would find it quite sexy to have a true, false, undetermined embeded in the language instead of using some home defined constants.

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• Using new syntax styles in .Net 3.5

  In this article we will see to new coding methodologies in .NET 3.5.

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• WPF tree data binding

  - by Am

  Hi, I have a well defined tree repository. Where I can rename items, move them up, down, etc. Add new and delete. The data is stored in a table as follows: Index Parent Label Left Right 1 0 root 1 14 2 1 food 2 7 3 2 cake 3 4 4 2 pie 5 6 5 1 flowers 8 13 6 5 roses 9 10 7 5 violets 11 12 Representing the following tree: (1) root (14) (2) food (7) (8) flowers (13) (3) cake (4) (5) pie (6) (9) roeses (10) (11) violets (12) or root food cake pie flowers roses violets Now, my problem is how to represent this in a bindable way, so that a TreeView can handle all the possible data changes? Renaming is easy, all I need is to make the label an updatble field. But what if a user moves flowers above food? I can make the relevant data changes, but they cause a complete data change to all other items in the tree. And all the examples I found of bindable hierarchies are good for non static trees.. So my current (and bad) solution is to reload the displayed tree after relocation change. Any direction will be good. Thanks

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• Binary Search Tree for specific intent

  - by Luís Guilherme

  We all know there are plenty of self-balancing binary search trees (BST), being the most famous the Red-Black and the AVL. It might be useful to take a look at AA-trees and scapegoat trees too. I want to do deletions insertions and searches, like any other BST. However, it will be common to delete all values in a given range, or deleting whole subtrees. So: I want to insert, search, remove values in O(log n) (balanced tree). I would like to delete a subtree, keeping the whole tree balanced, in O(log n) (worst-case or amortized) It might be useful to delete several values in a row, before balancing the tree I will most often insert 2 values at once, however this is not a rule (just a tip in case there is a tree data structure that takes this into account) Is there a variant of AVL or RB that helps me on this? Scapegoat-trees look more like this, but would also need some changes, anyone who has got experience on them can share some thougts? More precisely, which balancing procedure and/or removal procedure would help me keep this actions time-efficient?

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• "Subforms" associated with tree view in VB

  - by knomdeguerre

  I am using VB Express 2008 to demonstrate my ideas for an improved UI for an existing product for my colleagues at work. The current UI has a certain page with ten tabs, allowing the user to define up to ten "things". The available choices for each of the ten "things" are all the same. On each of the ten tabs, there is a checkbox to enable that definition. Generally, a user will never use more than 5 or 6 unique definitions, the rest will remain disabled. So far, my prototype has a tree view control with one branch to contain this list of definitions, Add and Delete buttons. My idea is: there is one sub-branch to start with (corresponding to the first tab in the current UI); if the user wants addtional definitions, they click Add and other branches are added to the tree view, up to maximum of ten. I think I should be able to create a "class" that has a sub-UI (like a sub-form in Access) along with behavior code, that can be instantiated with each press of the Add button; each instantiation's settings can be set independently and is displayed in the main UI form )in a panel or frame) when selected in the tree view. For example, suppose the user Adds to make a total of three definitions: the tree view now has three sub-branches, each of which presents the same sub-UI with settings that can be set specific to the selected sub-branch. I'm sure it's possible but not sure how to do it. I know a comprehensive "answer" might be complicated and long, but I may just need some quick hints to get underway - don't be shy! Thanks in advance!

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• WPF tree data binding model & repository

  - by Am

  Hi, I have a well defined tree repository. Where I can rename items, move them up, down, etc. Add new and delete. The data is stored in a table as follows: Index Parent Label Left Right 1 0 root 1 14 2 1 food 2 7 3 2 cake 3 4 4 2 pie 5 6 5 1 flowers 8 13 6 5 roses 9 10 7 5 violets 11 12 Representing the following tree: (1) root (14) (2) food (7) (8) flowers (13) (3) cake (4) (5) pie (6) (9) roeses (10) (11) violets (12) or root food cake pie flowers roses violets Now, my problem is how to represent this in a bindable way, so that a TreeView can handle all the possible data changes? Renaming is easy, all I need is to make the label an updatble field. But what if a user moves flowers above food? I can make the relevant data changes, but they cause a complete data change to all other items in the tree. And all the examples I found of bindable hierarchies are good for non static trees.. So my current (and bad) solution is to reload the displayed tree after relocation change. Any direction will be good. Thanks

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