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  • Using static variable in android

    - by michael
    Hi, In android, is it recommend to use static variable? E.g, implement a Singleton pattern in Java, I usually do: private static A the_instance; public static A getInstance() { if (the_instance == null) { the_instance = new A(); } return the_instance; } My question is when do that get free by android JVM? Thank you.

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  • Python: why can't descriptors be instance variables?

    - by Continuation
    Say I define this descriptor: class MyDescriptor(object): def __get__(self, instance, owner): return self._value def __set__(self, instance, value): self._value = value def __delete__(self, instance): del(self._value) And I use it in this: class MyClass1(object): value = MyDescriptor() >>> m1 = MyClass1() >>> m1.value = 1 >>> m2 = MyClass1() >>> m2.value = 2 >>> m1.value 2 So value is a class attribute and is shared by all instances. Now if I define this: class MyClass2(object) value = 1 >>> y1 = MyClass2() >>> y1.value=1 >>> y2 = MyClass2() >>> y2.value=2 >>> y1.value 1 In this case value is an instance attribute and is not shared by the instances. Why is it that when value is a descriptor it can only be a class attribute, but when value is a simple integer it becomes an instance attribute?

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  • What is the '@(' doing in this Perl code?

    - by Anthony Veckey
    In this code snippet: use strict; use warnings; use Data::Dumper; my $r = [qw(testing this thing)]; print Dumper($r); foreach my $row (@({$r}) { print "$row\n"; $row .= 'mod'; } print Dumper($r); print Dumper(@({$r}); I figured out that the '(' after the '@' in the foreach is causing this not to loop correctly. I have no idea why this code even works as there is no ending parenthesis. What is this doing? It looks to be creating a new variable on the fly, but shouldn't 'use strict' have fired or something? Please help explain what that '@(' is doing and why it still runs without an ending parenthesis.

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  • Is it possible to restrict how a method can be called in PHP?

    - by Ashley Ward
    Given that my class looks like this: class Methods{ function a(){ return 'a'; } function b(){ $this->a(); } function c(){ $this->a(); } } Is it possible to ensure that function a can only be called from function b? In the above example function c should fail. I could just include it in function b, but in the future I may want to let a() be called by some new functions (e.g. d() or e())

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  • PHP while(variable=mysql_fetch_assoc) - explanation

    - by Petr
    Hi, I have been working with C# so this is quite strange for me: while($variable=mysql_fetch_assoc) I have not been able to look up in PHP manual how it works. I guess that in each loop it advances to next element of assoc.array. But what is this generally called in PHP? I am just not used to see '=' in loop condition.

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  • Variable table or column names.

    - by Frank Computer
    INFORMIX-SQL or any other SQL-based DB: Suppose I have an app where depending on the value of some columns, example: company.code char(3) {abc} company.brach char(2) {01} Can I construct table name "abc01" for inclusion in SELECT * FROM abc01; ? In other words, a variable table name.. same question applies for column names.

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  • Require_once to variable

    - by swamprunner7
    I want to call require_once("test.php") but not display result and save it into variable like this: //pseudocode $test = require_once('test.php'); //some operations like $test = preg_replace(…); echo $test; Is it possible?

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  • How do I use a named_scope to filter records in my model

    - by kibyegon
    I have a model "Product" with a "description" field. Now I want to have a link in the index page that when clicked will show all products where the description is blank (empty). In the model I have defined a named_scope like this named_scope :no_description, :conditions => { :description => "" } I have checked that the named_scope works by calling Product.no_description.count on the console. As far as I know, the controller is then supposed to handle the filter request from the link on the "index" action but be able to distinguish it from the default which is view all products. def index @products = Product.all ... My problem is getting the controller handle the different request, what route to setup for the link on the view and the actual link on the view. Hope I explained my problem.

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  • Using functions and environments

    - by Eduardo Leoni
    Following the recent discussions here (e.g. 1, 2 ) I am now using environments in some of my code. My question is, how do I create functions that modify environments according to its arguments? For example: y <- new.env() with(y, x <- 1) f <- function(env,z) { with(env, x+z) } f(y,z=1) throws Error in eval(expr, envir, enclos) : object 'z' not found I am using environments to keep concurrently two sets of simulations apart (without refactoring my code, which I wrote for a single set of experiments).

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  • keeping track of multiple runs of the same function, part 2

    - by qwertymk
    This is related to this Anyway what I need is actually something slightly different I need some way of doing this: function run(arg) { this.ran = this.ran || false; if (!this.ran) init; /* code */ this.ran = true; } This works fine, I just want to make sure that this code works even when this in case it was called with call() or apply() Check this out for what I'm talking about, All of the calls after the first one should all be true, no matter the context

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  • find the total values get in a variable in php

    - by Hmwd
    hi, i am doing a shopping cart.i had a variable $total.when i add 1st product of price 200 i get $total=200 , when i add 2nd product of price 100 i get $total=200100 when i add 3rd product of price 400 i get $total=200100400 . i want to get $total=700. how to fix this problem? please help me........ thanks, Hmwd

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  • how can put a javascript variable in img tag

    - by ajithperuva
    I need to put a javascript variable as image source.That is my image tag should be in this format here i am adding my script document.getElementById("pricefilter").innerHTML ='' here variablename carries my image path.How can i put this in double quates.Please help to solve this

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  • jquery pass dynamic variable name

    - by Alessandro
    hi function liveUpdate(fld,value,id) { $.ajax({ type: 'POST', url: 'myurl.html', data: { fld:value, 'id': id }, success: function(data){//console.log(data); } }); } i want fld to be posted as fld's value not the variable name fld? i've tried to wrap around with eval but no luck any ideas? thanks

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  • how to get an xml in a variable

    - by sam
    I have a stored procedure that will return xml. I have delared a variable of type xml and trying to execute the following code declare @v xml set @v = execute get_xml @id, 33 whereas id is returned by another query. now it keeps compalinng about the following error Incorrect syntax near the keyword 'execute'.

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  • i can't get variable in function.

    - by kaym
    i can't read the variable in the function, i want to use it outside the function, here is my code. var contentLoader:URLLoader = new URLLoader(); contentLoader.load(new URLRequest("http://localhost/data.php")); function onComplete(event:Event):void { var txtu:String = event.target.data; } contentLoader.addEventListener(Event.COMPLETE, onComplete); trace(txtu); thanks.

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  • Missing $ on loop variable

    - by k0re
    Hi, 1 #!/usr/bin/perl 2 use strict; 3 use warnings; 4 5 my @array = qw[a b c]; 6 foreach my($a,$b,$c) (@array) { 7 print "$a , $b , $c\n"; 8 } I receive following error: Missing $ on loop variable What is wrong? I am using: perl v5.10.1 (*) built for x86_64-linux-thread-multi

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  • java app behind proxy to use http_proxy variable in linux

    - by rbbeltran
    hello java guys, im thinking of a simple java app (command line) that connects to the internet to download xml file, the problem is that my ubuntu is using a proxy to connect to internet with username and password (tru http_proxy ="http://:@:" ). So My question is, could it be possible to write a java app to use http_proxy variable? instead of programmatically setting http proxy and host in every app i will write.

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  • how to declare variable in POSTGRE

    - by user307880
    I try to declare a variable in a code like this, but it's doesn't work. Can you tell me what's the problem? ERROR: syntax error at or near "VARCHAR" LINE 2: p_country VARCHAR; DECLARE p_country VARCHAR; p_country : = ''; SELECT p_country;

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