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  • CUPS Web Admin Error 500 Unknown

    - by Floyd Resler
    I keep getting a 500 Unknown error whenever I navigate off the home page of my CUPS web admin. I'm sure I have something misconfigured but I'm not sure what. Here's my configuration: # # "$Id: cupsd.conf.in 8805 2009-08-31 16:34:06Z mike $" # # Sample configuration file for the CUPS scheduler. See "man cupsd.conf" for a # complete description of this file. # # Log general information in error_log - change "warn" to "debug" # for troubleshooting... LogLevel warn # Administrator user group... SystemGroup lpadmin sys root # Only listen for connections from the local machine. Listen 192.168.6.101:631 Listen /var/run/cups/cups.sock ServerName 192.168.6.101 # Show shared printers on the local network. Browsing On BrowseOrder allow,deny BrowseAllow all BrowseLocalProtocols CUPS BrowseAddress 192.168.6.255 # Default authentication type, when authentication is required... DefaultAuthType Basic # Restrict access to the server... Order allow,deny Allow From All Allow From 127.0.0.1 # Restrict access to the admin pages... AuthType Default Require user @SYSTEM Order allow,deny Allow From All Allow From 127.0.0.1 # Restrict access to configuration files... AuthType Default Require user @SYSTEM Order allow,deny Allow From All Allow From 127.0.0.1 # Set the default printer/job policies... # Job-related operations must be done by the owner or an administrator... Require user @OWNER @SYSTEM Order deny,allow # All administration operations require an administrator to authenticate... AuthType Default Require user @SYSTEM Order deny,allow # All printer operations require a printer operator to authenticate... AuthType Default Require user @SYSTEM Order deny,allow # Only the owner or an administrator can cancel or authenticate a job... Require user @OWNER @SYSTEM Order deny,allow Order deny,allow # Set the authenticated printer/job policies... # Job-related operations must be done by the owner or an administrator... AuthType Default Order deny,allow AuthType Default Require user @OWNER @SYSTEM Order deny,allow # All administration operations require an administrator to authenticate... AuthType Default Require user @SYSTEM Order deny,allow # All printer operations require a printer operator to authenticate... AuthType Default Require user @SYSTEM Order deny,allow # Only the owner or an administrator can cancel or authenticate a job... AuthType Default Require user @OWNER @SYSTEM Order deny,allow Order deny,allow # # End of "$Id: cupsd.conf.in 8805 2009-08-31 16:34:06Z mike $". #

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  • Form value not passed to Seam bean after a4j reRender

    - by Casper
    I'm making a webapp in Seam but ran into a problem I can't seem to fix. I have a JSF form where the customer can select a reservation type through a combobox. Based on the selected value, other form components gets rendered. For example: the customer selects Hours as reservation type, a panelGroup gets rendered where the customer can select a start- and an end hour. But if the customer would select 'part of the day' as reservation type, a selectOneMenu gets rendered where the customer can select a part of the day (morning, afternoon, evening) The rerendering well but the values of the components with a rendered conditional won't get passed to the bean. They stay null values. This is the code i'm talking about: <h:panelGrid columns="2"> <h:outputText value="Reservation Type" /> <h:selectOneMenu value="#{selectedPeriodPart}"> <s:selectItems value="#{productManager.getAvailableDayPartsSpot()}" var="daypart" label="#{daypart.label}"></s:selectItems> <s:convertEnum /> <a4j:support ajaxSingle="true" event="onchange" action="#" reRender="spot"></a4j:support> </h:selectOneMenu> <h:outputText id="date_spot" value="Date" /> <a4j:outputPanel id="calendar_spot" layout="block"> <rich:calendar value="#{reservation.reservationPeriod.startDate}" locale="en" cellWidth="24px" cellHeight="22px" style="width:200px" /> </a4j:outputPanel> <h:outputText rendered="#{selectedPeriodPart eq 'DAY_PART'}" value="Daypart" /> <h:selectOneMenu value="#{selectedDaypart}" rendered="#{selectedPeriodPart eq 'DAY_PART'}"> <f:selectItem id="si_morning" itemLabel="Morning (6:00 - 12:00)" itemValue="morning" /> <f:selectItem id="si_afternoon" itemLabel="Afternoon (12:00 - 18:00)" itemValue="afternoon" /> <f:selectItem id="si_evening" itemLabel="Evening (18:00 - 00:00)" itemValue="evening" /> </h:selectOneMenu> <h:outputText rendered="#{selectedPeriodPart eq 'HOURS'}" value="Hours" /> <h:panelGroup id="hours_spot" rendered="#{selectedPeriodPart eq 'HOURS'}"> <ui:include src="/includes/reservation/select_hours.xhtml" /> </h:panelGroup> </h:panelGrid> </s:div></code> Note: The calendar value do get passed back to the bean but the value of this piece of code doesn't (it does if you remove the rendered conditional):

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  • Making swap faster, easier to use and exception-safe

    - by FredOverflow
    I could not sleep last night and started thinking about std::swap. Here is the familiar C++98 version: template <typename T> void swap(T& a, T& b) { T c(a); a = b; b = c; } If a user-defined class Foo uses external ressources, this is inefficient. The common idiom is to provide a method void Foo::swap(Foo& other) and a specialization of std::swap<Foo>. Note that this does not work with class templates since you cannot partially specialize a function template, and overloading names in the std namespace is illegal. The solution is to write a template function in one's own namespace and rely on argument dependent lookup to find it. This depends critically on the client to follow the "using std::swap idiom" instead of calling std::swap directly. Very brittle. In C++0x, if Foo has a user-defined move constructor and a move assignment operator, providing a custom swap method and a std::swap<Foo> specialization has little to no performance benefit, because the C++0x version of std::swap uses efficient moves instead of copies: #include <utility> template <typename T> void swap(T& a, T& b) { T c(std::move(a)); a = std::move(b); b = std::move(c); } Not having to fiddle with swap anymore already takes a lot of burden away from the programmer. Current compilers do not generate move constructors and move assignment operators automatically yet, but as far as I know, this will change. The only problem left then is exception-safety, because in general, move operations are allowed to throw, and this opens up a whole can of worms. The question "What exactly is the state of a moved-from object?" complicates things further. Then I was thinking, what exactly are the semantics of std::swap in C++0x if everything goes fine? What is the state of the objects before and after the swap? Typically, swapping via move operations does not touch external resources, only the "flat" object representations themselves. So why not simply write a swap template that does exactly that: swap the object representations? #include <cstring> template <typename T> void swap(T& a, T& b) { unsigned char c[sizeof(T)]; memcpy( c, &a, sizeof(T)); memcpy(&a, &b, sizeof(T)); memcpy(&b, c, sizeof(T)); } This is as efficient as it gets: it simply blasts through raw memory. It does not require any intervention from the user: no special swap methods or move operations have to be defined. This means that it even works in C++98 (which does not have rvalue references, mind you). But even more importantly, we can now forget about the exception-safety issues, because memcpy never throws. I can see two potential problems with this approach: First, not all objects are meant to be swapped. If a class designer hides the copy constructor or the copy assignment operator, trying to swap objects of the class should fail at compile-time. We can simply introduce some dead code that checks whether copying and assignment are legal on the type: template <typename T> void swap(T& a, T& b) { if (false) // dead code, never executed { T c(a); // copy-constructible? a = b; // assignable? } unsigned char c[sizeof(T)]; std::memcpy( c, &a, sizeof(T)); std::memcpy(&a, &b, sizeof(T)); std::memcpy(&b, c, sizeof(T)); } Any decent compiler can trivially get rid of the dead code. (There are probably better ways to check the "swap conformance", but that is not the point. What matters is that it's possible). Second, some types might perform "unusual" actions in the copy constructor and copy assignment operator. For example, they might notify observers of their change. I deem this a minor issue, because such kinds of objects probably should not have provided copy operations in the first place. Please let me know what you think of this approach to swapping. Would it work in practice? Would you use it? Can you identify library types where this would break? Do you see additional problems? Discuss!

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  • MS SQL Server BEGIN/END vs BEGIN TRANS/COMMIT/ROLLBACK

    - by Rich
    I have been trying to find info on the web about the differences between these statements, and it seems to me they are identical but I can't find confirmation of that or any kind of comparison between the two. What is the difference between doing this: BEGIN -- Some update, insert, set statements END and doing this BEGIN TRANS -- Some update, insert, set statements COMMIT TRANS ? Note that there is only the need to rollback in the case of some exception or timeout or other general failure, there would not be a conditional reason to rollback.

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  • Lighttpd check request headers in configuration

    - by Mike Hayes
    Hi I was wondering if it was possible in the configuration of Lighttpd to read request headers, I've searched and searched.. apparently it's not possible. For example, conditional configuration based upon IP address: $HTTP["remoteip"] == "0.0.0.0" { // Do something } Is there something similar to check headers, for example: $HTTP["X-Some-Header"] == "Value" { // Do something } I'm thinking there isn't but thought I would post here as a last resort. Google didn't help much, and Lighttpd documentation would suggest this is not possible. Thanks Mike

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  • Required help to Increase the performance of the MySQL query

    - by Joseph
    Hi all, I am using a following query in MySQl for fetching data from a table. Its taking too long because the conditional check within the aggregate function.Please help how to make it faster SELECT testcharfield ,SUM(IF (Type = 'pi',quantity, 0)) AS OB ,SUM(IF (Type = 'pe',quantity, 0)) AS CB FROM Table1 WHERE sequenceID = 6107 GROUP BY testcharfield

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  • How can I get this menu to behave in IE6?

    - by Jordan
    I have a site whose menu is functioning incorrectly in IE6, and only IE6. A live preview of the site can be seen here. The HTML & CSS are too long to post here but please view the source and the CSS. I have implemented conditional comments and the IE6 Update jQuery plugin. Neither work.

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  • Using JavaScript in WordPress: throw all jQuery plugins in, or is there a way to conditionally load?

    - by ineedtosleep
    I'm relatively new with WordPress theming and JavaScript, though not incompetent with either. I'm looking to have a maximum of 10 jQuery plugins to go on the blog, but I'm wondering if there's a way to have them load only when needed, as I don't want any unnecessary loading for the users. Something similar in something I know a little bit more of would be the conditional comments in IE <!--[IF IE]> @import ie.css <![endif]-->.

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  • How to access static members in a Velocity template?

    - by matt b
    I'm not sure if there is a way to do this in Velocity or not: I have a User POJO which a property named Status, which looks like an enum (but it is not, since I am stuck on Java 1.4), the definition looks something like this: public class User { // default status to User private Status status = Status.USER; public void setStatus(Status status) { this.status = status; } public Status getStatus() { return status; } And Status is a static inner class: public static final class Status { private String statusString; private Status(String statusString) { this.statusString = statusString; } public final static Status USER = new Status("user"); public final static Status ADMIN = new Status("admin"); public final static Status STATUS_X = new Status("blah"); //.equals() and .hashCode() implemented as well } With this pattern, a user status can easily be tested in a conditional such as if(User.Status.ADMIN.equals(user.getStatus())) ... ... without having to reference any constants for the status ID, any magic numbers, etc. However, I can't figure out how to test these conditionals in my Velocity template with VTL. I'd like to just print a simple string based upon the user's status, such as: Welcome <b>${user.name}</b>! <br/> <br/> #if($user.status == com.company.blah.User.Status.USER) You are a regular user #elseif($user.status == com.company.blah.User.Status.ADMIN) You are an administrator #etc... #end But this throws an Exception that looks like org.apache.velocity.exception.ParseErrorException: Encountered "User" at webpages/include/dashboard.inc[line 10, column 21] Was expecting one of: "[" ... From the VTL User Guide, there is no mention of accessing a Java class/static member directly in VTL, it appears that the right hand side (RHS) of a conditional can only be a number literal, string literal, property reference, or method reference. So is there any way that I can access static Java properties/references in a Velocity template? I'm aware that as a workaround, I could embed the status ID or some other identifier as a reference in my controller (this is a web MVC application using Velocity as the View technology), but I strongly do not want to embed any magic numbers or constants in the view layer.

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  • Prevent ASP.NET MVC Bundles Loading more than once

    - by Tim
    is there an inbuilt method of tracking if a bundle has already been loaded? I have several edit views which forexample require jquery and jquery.Validate etc libraries. Which i don't need to reference on the main layout page. Since a page could consist of several different conditional libraries ... ideally i would like @scripts.Render to know if i have already referenced a library and prevent its reloading. Cheers Tim

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  • Problem with GCC calling static templates functions in templated parent class.

    - by Adisak
    I have some code that compiles and runs on MSVC++ but will not compile on GCC. I have made a test snippet that follows. My goal was to move the static method from BFSMask to BFSMaskSized. Can someone explain what is going on with the errors (esp. the weird 'operator<' error)? Thank you. In the case of both #defines are 0, then the code compiles on GCC. #define DOESNT_COMPILE_WITH_GCC 0 #define FUNCTION_IN_PARENT 0 I get errors if I change either #define to 1. Here are the errors I see. #define DOESNT_COMPILE_WITH_GCC 0 #define FUNCTION_IN_PARENT 1 Test.cpp: In static member function 'static typename Snapper::BFSMask<T>::T_Parent::T_SINT Snapper::BFSMask<T>::Create_NEZ(TCMP)': Test.cpp(492): error: 'CreateMaskFromHighBitSized' was not declared in this scope #define DOESNT_COMPILE_WITH_GCC 1 #define FUNCTION_IN_PARENT 0 Test.cpp: In static member function 'static typename Snapper::BFSMask<T>::T_Parent::T_SINT Snapper::BFSMask<T>::Create_NEZ(TCMP) [with TCMP = int, T = int]': Test.cpp(500): instantiated from 'TVAL Snapper::BFWrappedInc(TVAL, TVAL, TVAL) [with TVAL = int]' Test.cpp(508): instantiated from here Test.cpp(490): error: invalid operands of types '<unresolved overloaded function type>' and 'unsigned int' to binary 'operator<' #define DOESNT_COMPILE_WITH_GCC 1 #define FUNCTION_IN_PARENT 1 Test.cpp: In static member function 'static typename Snapper::BFSMask<T>::T_Parent::T_SINT Snapper::BFSMask<T>::Create_NEZ(TCMP) [with TCMP = int, T = int]': Test.cpp(500): instantiated from 'TVAL Snapper::BFWrappedInc(TVAL, TVAL, TVAL) [with TVAL = int]' Test.cpp(508): instantiated from here Test.cpp(490): error: invalid operands of types '<unresolved overloaded function type>' and 'unsigned int' to binary 'operator<' Here is the code namespace Snapper { #define DOESNT_COMPILE_WITH_GCC 0 #define FUNCTION_IN_PARENT 0 // MASK TYPES // NEZ - Not Equal to Zero #define BFSMASK_NEZ(A) ( ( A ) | ( 0 - A ) ) #define BFSELECT_MASK(MASK,VTRUE,VFALSE) ( ((MASK)&(VTRUE)) | ((~(MASK))&(VFALSE)) ) template<typename TVAL> TVAL BFSelect_MASK(TVAL MASK,TVAL VTRUE,TVAL VFALSE) { return(BFSELECT_MASK(MASK,VTRUE,VFALSE)); } //----------------------------------------------------------------------------- // Branch Free Helpers template<int BYTESIZE> struct BFSMaskBase {}; template<> struct BFSMaskBase<2> { typedef UINT16 T_UINT; typedef SINT16 T_SINT; }; template<> struct BFSMaskBase<4> { typedef UINT32 T_UINT; typedef SINT32 T_SINT; }; template<int BYTESIZE> struct BFSMaskSized : public BFSMaskBase<BYTESIZE> { static const int SizeBytes = BYTESIZE; static const int SizeBits = SizeBytes*8; static const int MaskShift = SizeBits-1; typedef typename BFSMaskBase<BYTESIZE>::T_UINT T_UINT; typedef typename BFSMaskBase<BYTESIZE>::T_SINT T_SINT; #if FUNCTION_IN_PARENT template<int N> static T_SINT CreateMaskFromHighBitSized(typename BFSMaskBase<N>::T_SINT inmask); #endif }; template<typename T> struct BFSMask : public BFSMaskSized<sizeof(T)> { // BFSMask = -1 (all bits set) typedef BFSMask<T> T_This; // "Import" the Parent Class typedef BFSMaskSized<sizeof(T)> T_Parent; typedef typename T_Parent::T_SINT T_SINT; #if FUNCTION_IN_PARENT typedef T_Parent T_MaskGen; #else typedef T_This T_MaskGen; template<int N> static T_SINT CreateMaskFromHighBitSized(typename BFSMaskSized<N>::T_SINT inmask); #endif template<typename TCMP> static T_SINT Create_NEZ(TCMP A) { //ReDefineType(const typename BFSMask<TCMP>::T_SINT,SA,A); //const typename BFSMask<TCMP>::T_SINT cmpmask = BFSMASK_NEZ(SA); const typename BFSMask<TCMP>::T_SINT cmpmask = BFSMASK_NEZ(A); #if DOESNT_COMPILE_WITH_GCC return(T_MaskGen::CreateMaskFromHighBitSized<sizeof(TCMP)>(cmpmask)); #else return(CreateMaskFromHighBitSized<sizeof(TCMP)>(cmpmask)); #endif } }; template<typename TVAL> TVAL BFWrappedInc(TVAL x,TVAL minval,TVAL maxval) { const TVAL diff = maxval-x; const TVAL mask = BFSMask<TVAL>::Create_NEZ(diff); const TVAL incx = x + 1; return(BFSelect_MASK(mask,incx,minval)); } SINT32 currentsnap = 0; SINT32 SetSnapshot() { currentsnap=BFWrappedInc<SINT32>(currentsnap,0,20); return(currentsnap); } }

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  • Deployment project in VisualStudio: Is the output in Debug or Releaase mode?

    - by serhio
    I have a solution in Visual studio containing a winform project(WinProj) and a deployment project for WinProj. I added to the deployment project the primary output from WinProj. Does it be compiled in Debug or Release mode? I am asking because in the WinProj code I have conditional precompiler statements #if DEBUG throw; #endif will or not be considered this code in the setup project?

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  • How to create 2 different scripts for 2 browsers (IE+all the rest)

    - by Barnabas Nagy
    I'm trying to solve an IE CSS issue by using conditional tags. My jQuery that does the job of tabbed box effect calls an id that is inside the conditional tags. I've given new ids to IE so on IE the jQuery is not working. I tried to duplicate the script with the new id in one of the script but the 2 scripts seems to get in conflict. My jQuery (in between the head tags) is (for all all browsers except IE): <script> var currentTab = 0; // Set to a different number to start on a different tab. function openTab(clickedTab) { var thisTab = $(".tabbed-box .tabs a").index(clickedTab); $(".tabbed-box .tabs li a").removeClass("active"); $(".tabbed-box .tabs li a:eq("+thisTab+")").addClass("active"); $(".tabbed-box .tabbed-content").hide(); $(".tabbed-box .tabbed-content:eq("+thisTab+")").show(); currentTab = thisTab; } $(document).ready(function() { $(".tabs li:eq(0) a").css("border-left", "none"); $(".tabbed-box .tabs li a").click(function() { openTab($(this)); return false; }); $(".tabbed-box .tabs li a:eq("+currentTab+")").click() }); </script> And I would need this for IE: <script> var currentTab = 0; // Set to a different number to start on a different tab. function openTab(clickedTab) { var thisTab = $(".tabbed-box .tabs a").index(clickedTab); $(".tabbed-box ie-.tabs li a").removeClass("active"); $(".tabbed-box ie-.tabs li a:eq("+thisTab+")").addClass("active"); $(".tabbed-box .tabbed-content").hide(); $(".tabbed-box .tabbed-content:eq("+thisTab+")").show(); currentTab = thisTab; } $(document).ready(function() { $(".ie-tabs li:eq(0) a").css("border-left", "none"); $(".tabbed-box .ie-tabs li a").click(function() { openTab($(this)); return false; }); $(".tabbed-box .ie-tabs li a:eq("+currentTab+")").click() }); </script> Having the 2 scripts in the head conflicts with each other. Maybe there is a way to combine them?

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  • Cross browser window close event

    - by slik
    Is there a solution for cross browser event. I need to check if user closes their window and to throw an ajax request to my database to sign them out. I've looked everyone but most cases its not working in all browsers. Anyone have a solution? Or Alternative on how to do this perhaps a conditional statement depending on the browser? Thanks!

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  • How can I recreate a SQL statement using NHibernate that has an inner select case?

    - by brianberns
    I am trying to recreate something like the following SQL using NHibernate criteria: select Range, count(*) from ( select case when ent.ID between 'A' and 'N' then 'A-M' else 'Other' end as Range from Subject ) tbl group by tbl.Range I am able to create the inner select as follows: session.CreateCriteria<Subject>() .SetProjection( Projections.Conditional( Expression.Between("Name", "A", "N"), Projections.Constant("A-M"), Projections.Constant("Other"))) .List(); However, I can't figure out how to pipe those results into a grouping by row count.

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  • What are incentives (if any) to use WinRT instead of .Net?

    - by Ark-kun
    Let's compare WinRT with .Net .Net .Net is the 13+ years evolution of COM. Three main parts of .Net are execution environment, standard libraries and supported languages. CLR is the native-code execution environment based on COM .Net Framework has a big set of standard libraries (implemented using managed and native code) that can be used from all .Net languages. There are .Net classes that allow using OS APIs. WPF or Silverlight provide a XAML-based UI framework .Net can be used with C++, C#, Javascript, Python, Ruby, VB, LISP, Scheme and many other languages. C++/.Net is a variation of the C++ language that allows interaction with .Net objects. .Net supports inheritance, generics, operator and method overloading and many other features. .Net allows creating apps that run on Windows (XP, 7, 8 Pro (Desktop and Metro), RT, CE, etc), Mac OS, Linux (+ other *nix); iOS, Android, Windows Phone (7, 8); Internet Explorer, Chrome, Firefox; XBox 360, Playstation Suite; raw microprocessors. There is support for creating games (2D/3D) using any managed language or C++. Created by Developer Division WinRT WinRT is based on COM. Three main parts of WinRT are execution environment, standard libraries and supported languages. WinRT has a native-code execution environment based on COM WinRT has a set of standard libraries that more or less can be used from WinRT languages. There are WinRT classes that allow using OS APIs. Unnamed Silverlight clone provides a XAML-based UI framework WinRT can be used with C++, C#, Javascript, VB. C++/CX is a variation of the C++ language that allows interaction with WinRT objects. Custom WinRT components don't support inheritance (classes must be sealed), generics, operator overloading and many other features. WinRT allows creating apps that run on Windows 8 Pro and RT (Metro only); Windows Phone 8 (limited). There is support for creating games (2D/3D) using C++ only. Ordered by Windows Team I think that all the aspects except the last ones are very important for developers. On the other hand it seems that the most important aspect for Microsoft is the last one. So, given the above comparison of conceptually identical technologies, what are incentives (if any) to use WinRT instead of .Net?

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  • ms excel find and replace @ symbol results in broken formula

    - by Loopo
    I'm trying to search and replace in excel, the column is formatted as 'Text'. Find: [@ replace with: @ Whenever this finds a match at the start of a cell i.e the cell contents start with [@ and tries to replace that with @ the result is an error 'This function is not valid' I guess that since the @ operator is for references, this is causing the cell to be interpreted differently (not as text anymore) How do I make this replacement work? Copy/paste into another program is not a good option because some of the cells contain line-breaks.

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  • Python/Biomolecular Physics- Trying to code a simple stochastic simulation of a system exhibiting co

    - by user359597
    *edited 6/17/10 I'm trying to understand how to improve my code (make it more pythonic). Also, I'm interested in writing more intuitive 'conditionals' that would describe scenarios that are commonplace in biochemistry. The conditional criteria in the below program is explained in Answer #2, but I am not satisfied with it- it is correct, but isn't obvious and isn't easy to implement for more complicated conditional scenarios. Ideas welcome. Comments/criticisms welcome. First posting experience @ stackoverflow- please comment on etiquette if needed. The code generates a list of values that are the solution to the following exercise: "In a programming language of your choice, implement Gillespie’s First Reaction Algorithm to study the temporal behaviour of the reaction A---B in which the transition from A to B can only take place if another compound, C, is present, and where C dynamically interconverts with D, as modelled in the Petri-net below. Assume that there are 100 molecules of A, 1 of C, and no B or D present at the start of the reaction. Set kAB to 0.1 s-1 and both kCD and kDC to 1.0 s-1. Simulate the behaviour of the system over 100 s." def sim(): # Set the rate constants for all transitions kAB = 0.1 kCD = 1.0 kDC = 1.0 # Set up the initial state A = 100 B = 0 C = 1 D = 0 # Set the start and end times t = 0.0 tEnd = 100.0 print "Time\t", "Transition\t", "A\t", "B\t", "C\t", "D" # Compute the first interval transition, interval = transitionData(A, B, C, D, kAB, kCD, kDC) # Loop until the end time is exceded or no transition can fire any more while t <= tEnd and transition >= 0: print t, '\t', transition, '\t', A, '\t', B, '\t', C, '\t', D t += interval if transition == 0: A -= 1 B += 1 if transition == 1: C -= 1 D += 1 if transition == 2: C += 1 D -= 1 transition, interval = transitionData(A, B, C, D, kAB, kCD, kDC) def transitionData(A, B, C, D, kAB, kCD, kDC): """ Returns nTransition, the number of the firing transition (0: A->B, 1: C->D, 2: D->C), and interval, the interval between the time of the previous transition and that of the current one. """ RAB = kAB * A * C RCD = kCD * C RDC = kDC * D dt = [-1.0, -1.0, -1.0] if RAB > 0.0: dt[0] = -math.log(1.0 - random.random())/RAB if RCD > 0.0: dt[1] = -math.log(1.0 - random.random())/RCD if RDC > 0.0: dt[2] = -math.log(1.0 - random.random())/RDC interval = 1e36 transition = -1 for n in range(len(dt)): if dt[n] > 0.0 and dt[n] < interval: interval = dt[n] transition = n return transition, interval if __name__ == '__main__': sim()

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  • C++0x rvalue references - lvalues-rvalue binding

    - by Doug
    This is a follow-on question to http://stackoverflow.com/questions/2748866/c0x-rvalue-references-and-temporaries In the previous question, I asked how this code should work: void f(const std::string &); //less efficient void f(std::string &&); //more efficient void g(const char * arg) { f(arg); } It seems that the move overload should probably be called because of the implicit temporary, and this happens in GCC but not MSVC (or the EDG front-end used in MSVC's Intellisense). What about this code? void f(std::string &&); //NB: No const string & overload supplied void g1(const char * arg) { f(arg); } void g2(const std::string & arg) { f(arg); } It seems that, based on the answers to my previous question that function g1 is legal (and is accepted by GCC 4.3-4.5, but not by MSVC). However, GCC and MSVC both reject g2 because of clause 13.3.3.1.4/3, which prohibits lvalues from binding to rvalue ref arguments. I understand the rationale behind this - it is explained in N2831 "Fixing a safety problem with rvalue references". I also think that GCC is probably implementing this clause as intended by the authors of that paper, because the original patch to GCC was written by one of the authors (Doug Gregor). However, I don't this is quite intuitive. To me, (a) a const string & is conceptually closer to a string && than a const char *, and (b) the compiler could create a temporary string in g2, as if it were written like this: void g2(const std::string & arg) { f(std::string(arg)); } Indeed, sometimes the copy constructor is considered to be an implicit conversion operator. Syntactically, this is suggested by the form of a copy constructor, and the standard even mentions this specifically in clause 13.3.3.1.2/4, where the copy constructor for derived-base conversions is given a higher conversion rank than other implicit conversions: A conversion of an expression of class type to the same class type is given Exact Match rank, and a conversion of an expression of class type to a base class of that type is given Conversion rank, in spite of the fact that a copy/move constructor (i.e., a user-defined conversion function) is called for those cases. (I assume this is used when passing a derived class to a function like void h(Base), which takes a base class by value.) Motivation My motivation for asking this is something like the question asked in http://stackoverflow.com/questions/2696156/how-to-reduce-redundant-code-when-adding-new-c0x-rvalue-reference-operator-over ("How to reduce redundant code when adding new c++0x rvalue reference operator overloads"). If you have a function that accepts a number of potentially-moveable arguments, and would move them if it can (e.g. a factory function/constructor: Object create_object(string, vector<string>, string) or the like), and want to move or copy each argument as appropriate, you quickly start writing a lot of code. If the argument types are movable, then one could just write one version that accepts the arguments by value, as above. But if the arguments are (legacy) non-movable-but-swappable classes a la C++03, and you can't change them, then writing rvalue reference overloads is more efficient. So if lvalues did bind to rvalues via an implicit copy, then you could write just one overload like create_object(legacy_string &&, legacy_vector<legacy_string> &&, legacy_string &&) and it would more or less work like providing all the combinations of rvalue/lvalue reference overloads - actual arguments that were lvalues would get copied and then bound to the arguments, actual arguments that were rvalues would get directly bound. Questions My questions are then: Is this a valid interpretation of the standard? It seems that it's not the conventional or intended one, at any rate. Does it make intuitive sense? Is there a problem with this idea that I"m not seeing? It seems like you could get copies being quietly created when that's not exactly expected, but that's the status quo in places in C++03 anyway. Also, it would make some overloads viable when they're currently not, but I don't see it being a problem in practice. Is this a significant enough improvement that it would be worth making e.g. an experimental patch for GCC?

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  • GTK+ Compile Error

    - by Alon
    When trying to compile GTK+ with target for DirectFB, it throws: configure: error: conditional "XINPUT_NONE" was never defined. Usually this means the macro was only invoked conditionally. Any ideas? Thanks.

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  • if-else structure

    - by Halo
    I have these long statements that I will refer to as x,y etc. here. My conditional statements' structure goes like this: if(x || y || z || q){ if(x) do someth else if (y) do something if(z) do something else if(q) do something } else do smthing Is there a better, shorter way to write this thing? Thanks

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