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  • Instance variables vs. class variables in Python

    - by deamon
    I have Python classes, of which I need only one instance at runtime, so it would be sufficient to have the attributes only once per class and not per instance. If there would be more than one instance (what won't happen), all instance should have the same configuration. I wonder which of the following options would be better or more "idiomatic" Python. Class variables: MyController(Controller): path = "something/" childs = [AController, BController] def action(request): pass Instance ariables: MyController(Controller): def __init__(self): self.path = "something/" self.childs = [AController, BController] def action(self, request): pass

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  • How to Use an Environment Variable as an Environment Variable Name

    - by Synetech inc.
    Hi, In my pursuit of a solution to another environment-variable/batch-file related problem, I have once again come across a problem I have visited before (but cannot for the life of me remember how, or even if I solved it). Say you have two BAT files (or one batch file and the command line). How can one pass an environment variable name to the other so that it can read the variable? The following example does not work: A.BAT: @call b.bat path B.BAT: @echo %%1% > A.BAT > %1 > B.BAT path > %1 It is easy enough to pass the environment variable name, but the callee cannot seem to use it. (I don’t remember if or how I dealt with this the last time it came up, but I suspect it required the less-than-ideal use of redirecting temporary BAT files and calling them and such.) Any ideas? Thanks.

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  • How do I change variables from different classes?

    - by Dan T
    Before I delve into it, I'm very new to Android and I have just started learning Java last month. I've hit bumps while trying to develop my first simple app. Most of these hurdles were jumped thanks to random tutorials online. MY CODE IS VERY MESSY. Any tips are appreciated. The question above is quite broad, but this is what I want to do: It's a essentially a blood alcohol content calculator / drink keeper-tracker. Basic layout: http://i.imgur.com/JGuh7.jpg The buttons along the bottom are just regular buttons, not ImageButtons (had problems with that) Here's some example code of one: <Button android:id="@+id/Button01" android:layout_width="wrap_content" android:layout_marginRight="5dp" android:background="@drawable/addbeer"/> The buttons and TextView are all in main.xml. I have variables defined in a class called Global.java: package com.dantoth.drinkingbuddy; import android.app.Activity; public class Global extends Activity{ public static double StandardDrinks = 0; public static double BeerOunces = 12; public static double BeerPercentAlcohol = .05; public static double BeerDrink = BeerOunces * BeerPercentAlcohol; public static double BeerDrinkFinal = BeerDrink * 1.6666666; public static double ShotOunces = 1.5; public static double ShotPercentAlcohol = .4; public static double ShotDrink = ShotOunces * ShotPercentAlcohol; public static double ShotDrinkFinal = ShotDrink * 1.6666666; public static double WineOunces = 5; public static double WinePercentAlcohol = .12; public static double WineDrink = WineOunces * WinePercentAlcohol; public static double WineDrinkFinal = WineDrink * 1.6666666; public static double OtherOunces; public static double OtherPercentAlcohol; public static double OtherDrink = OtherOunces * (OtherPercentAlcohol * .01); public static double OtherDrinkFinal = OtherDrink * 1.6666666; public static double GenderConstant = 7.5; //9 for female public static double Weight = 180; public static double TimeDrinking = 60; public static double Hours = TimeDrinking / 60; public static double Bac = ((StandardDrinks / 2) * (GenderConstant / Weight)) - (0.017 * Hours); } The last variable is the important part. It calculates your BAC based on the factors involved. When I press the add beer button (Button01) I make it add 1 to StandardDrinks, simulating drinking one beer. The other variables in the Bac formula have values assigned to them in Global.java. The code that makes the beer button do stuff is in my regular class, drinkingbuddy.java: public class DrinkingBuddy extends Activity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); Button button = (Button) findViewById(R.id.Button01); button.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { Global.StandardDrinks = Global.StandardDrinks + Global.BeerDrinkFinal; Toast.makeText(DrinkingBuddy.this, "Mmmm... Beer", Toast.LENGTH_SHORT).show(); } }); By my perception, StandardDrinks should now have a value of 1. However, when I click the Calculate BAC button (Button05) it merely outputs the variable Bac as if StandardDrinks was still set to 0. Here is the code for the Calculate BAC button (Button05): Button button4 = (Button) findViewById(R.id.Button05); button4.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { TextView texty; texty = (TextView) findViewById(R.id.texty1); texty.setText("Your BAC is " + Global.Bac ); } }); It outputs the following to the text view: "Your BAC is -0.017". This is the Bac value for if StandardDrinks was still 0, so obviously there is some problem communicating between the classes. Can anyone help me?? The other elements of the formula (weight, time spent drinking, and the alcohol %'s and such) are variables because I will ultimately allow the user to change those values in the settings. I've heard around the water cooler that global variables are not good programming style, but this is the closest I've come to getting it to work. Any other ways of doing it are very much welcomed!

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  • order of operations for environment variables

    - by alyda
    I want to understand how environment variables are set and reset (overridden). I'm running Apache/2.2.24 (Unix) PHP/5.4.14 on a mac . My theory is this: Environment vars can be set in bash, then they can be overwritten with httpd.conf preceding a VirtualHost directive that precedes php.ini, which can then be overwritten by .htaccess (if allowable) and finally by PHP I tried the following: setting environment variable in bash: I added export ENVIRONMENT='local' to my ~/.bashrc file, restarted apache and did not get any output from print_r($_ENV); (in a simple index.php file at the root of my webserver). I also tried putting ENVIRONMENT='local' into /etc/environment, and restarting apache, nothing, as well as /etc/bashrc, restart apache. still nothing. setting environment variable in httpd.conf: I added SetEnv ENVIRONMENT 'local-httpd to the end of my /etc/apache2/httpd.conf file (but before I load other conf files, such as virtual host [Include /private/etc/apache2/other/*.conf]). I now see the variable in the array print_r($_SERVER); but not print_r($_ENV);. setting environment variable in httpd-vhosts.conf: I added SetEnv ENVIRONMENT 'local-vhost to my /etc/apache2/extra/httpd-vhosts.conf file in my generic directive that points to my default document root. I now see the variable has been overwritten (to local-vhost from local-httpd, so I know where the variable is getting set). setting environment variable in php.ini: while searching for a proper place to put my environment variable, I noticed that variables_order = "GPCS" was set to the production value rather than EGPCS. I changed it, restarted my server and found that I was now getting output for print_r($_ENV); but not my expected custom variable. It also appears that I am not able to set a custom variable in this file. Please tell me if I am wrong setting environment variable in .htaccess: I added SetEnv ENVIRONMENT 'local-htaccess'. This worked as expected, overwriting all other values that were set. setting / overwriting environment variable in PHP: if (...) { putenv('ENVIRONMENT=local'); } I'm asking this question because I have a lot of local and remote testing servers, some of which may or may not allow me access to modify httpd, httpd-vhost, php.ini or environment variables. I want to understand what is best for those difference scenarios (shared hosting, heroku, local servers, etc) I obviously don't know how to properly set the environment variable in bash in a way that php can use it, I'd like to know how to do that (as I think Heroku does something similar with heroku config set...)

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  • Method flags as arguments or as member variables?

    - by Martin
    I think the title "Method flags as arguments or as member variables?" may be suboptimal, but as I'm missing any better terminology atm., here goes: I'm currently trying to get my head around the problem of whether flags for a given class (private) method should be passed as function arguments or via member variable and/or whether there is some pattern or name that covers this aspect and/or whether this hints at some other design problems. By example (language could be C++, Java, C#, doesn't really matter IMHO): class Thingamajig { private ResultType DoInternalStuff(FlagType calcSelect) { ResultType res; for (... some loop condition ...) { ... if (calcSelect == typeA) { ... } else if (calcSelect == typeX) { ... } else if ... } ... return res; } private void InteralStuffInvoker(FlagType calcSelect) { ... DoInternalStuff(calcSelect); ... } public void DoThisStuff() { ... some code ... InternalStuffInvoker(typeA); ... some more code ... } public ResultType DoThatStuff() { ... some code ... ResultType x = DoInternalStuff(typeX); ... some more code ... further process x ... return x; } } What we see above is that the method InternalStuffInvoker takes an argument that is not used inside this function at all but is only forwarded to the other private method DoInternalStuff. (Where DoInternalStuffwill be used privately at other places in this class, e.g. in the DoThatStuff (public) method.) An alternative solution would be to add a member variable that carries this information: class Thingamajig { private ResultType DoInternalStuff() { ResultType res; for (... some loop condition ...) { ... if (m_calcSelect == typeA) { ... } ... } ... return res; } private void InteralStuffInvoker() { ... DoInternalStuff(); ... } public void DoThisStuff() { ... some code ... m_calcSelect = typeA; InternalStuffInvoker(); ... some more code ... } public ResultType DoThatStuff() { ... some code ... m_calcSelect = typeX; ResultType x = DoInternalStuff(); ... some more code ... further process x ... return x; } } Especially for deep call chains where the selector-flag for the inner method is selected outside, using a member variable can make the intermediate functions cleaner, as they don't need to carry a pass-through parameter. On the other hand, this member variable isn't really representing any object state (as it's neither set nor available outside), but is really a hidden additional argument for the "inner" private method. What are the pros and cons of each approach?

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  • Access variables from a number of sources

    - by mac_55
    I'm creating my first game, and I've currently set up a 'GameState' class, to store player health etc. inside. This class is currently instantiated from the AppDelegate as I need to access it from all over my game. This is fine. For each class I'm working in, I can access the app delegate, and then find the GameState object... however, it seems very messy. I'm tempted to find a way (I'm still a newbie) to define the GameState instance as being some sort of global variable so that I can access it from all over with ease... but my little bit of reading on variable scope makes me uneasy about doing this, even if I knew how. Any ideas of the best way to define and access this class? It'll be used for everything from player health, to items they've found, any personalisation etc. Thanks!

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  • one variable and multiple controllers..

    - by Simon
    I'm working on a web application, using the CAKEPHP framework. Herefor i need to request one variable on multiple pages (all pages have different controllers). it is oubvious that i get a error on several pages, since the variable isn't declared in all the different controllers. Is there a workaround for this? i've already tried the app:: import to import a controller in another controller, but this doens't seem to work (still get a undefined variable error). Thnx for your cooperation! Regards, Simon

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  • Android Static Variable Scope and Lifetime

    - by Edison
    I have an application that has a Service uses a ArrayList to store in the background for a very long time, the variable is initialized when the service started. The service is in the background and there will be frequent access to the variable (that's why i don't want to use file management or settings since it will be very expensive for a file I/O for the sake of battery life). The variable will likely to be ~1MB-2MB over its life tie. Is it safe to say that it will never be nulled by GC or the system or is there any way to prevent it? Thanks.

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  • set static member pointer variables

    - by Chris
    I'm trying to set a static pointer variable in a class but I'm getting these errors for each variable I try to set. error C4430: missing type specifier - int assumed. Note: C++ does not support default-int error C2040: 'xscroll' : 'int' differs in levels of indirection from 'float *' error C2440: 'initializing' : cannot convert from 'float **' to 'int' Here is the code Enemy.h #include <windows.h> #include "Player.h" class Enemy { public: Enemy(float xPos, float yPos); Enemy(void); ~Enemy(void); //update the position of the user controlled object. void updatePosition(float timeFactor); //loads all the enemy textures void static loadTextures(); //creates a set number of enemies void static createEnemies(int numEnemies, Enemy * enemyArray); GLuint static enemyTex; static float * xscroll; static float * yscroll; static Player * player; private: bool checkCollison(float x, float y, int radius); float XPos; float YPos; }; trying to set variables Enemy::xscroll = &xscroll; Enemy::yscroll = &yscroll; Enemy::player = &player;

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  • Get all Javascript Variables?

    - by Matrym
    Is there a way for javascript to detect all assigned variables? For example, if one js file creates a bunch of vars (globally scoped), can a subsequent file get all the vars without knowing what they're named and which might exist? Thanks in advance :)

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  • Variable within variable possible?

    - by JM4
    I am trying to create a loop statement for some of my code and am wondering how I can put a variable within another variable. For example: <?php $j=1; while ($j <= 9): { $f$jfname = $_SESSION['F$jFirstName']; $f$jmi = $_SESSION['F$jMI']; $f$jlname = $_SESSION['F$jLastName']; } $j++; endwhile; ?> Where the goal is to have the j variable increase during the loop and change the values as: $f1fname $f2fname $f3fname and so on. Any ideas?

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  • send javaScript variable to php variable

    - by mrbunyrabit
    First i thought that i had to convert javascript to php, but then i found out that cant because of server and client side executions. So now I simply want to send ONE variable <script type="text/javascript"> function scriptvariable() { var theContents = "the variable"; } </script> to a php variable <?php $phpvariable ?> That function in the javascript executes when lets say i click on a button. Now i have Nooo idea how to get that phpvariable Equal to the javascript one so i can use that phpvariable to look up stuff in my Database. I know i can add it to my url or some thing, and just refresh the page.. But id like to do it with AJAX as further in my webpage i might have to use this Ajax method.. So is there an easy way to do this without having to dump pages of code on my page to do one simple thing?

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  • What does @@variable mean in Ruby?

    - by Andrew
    What are Ruby variables preceded with double at signs (@@)? My understanding of a variable preceded with an at sign is that it is an instance variable, like this in PHP: PHP version class Person { public $name; public function setName($name) { $this->name = $name; } public function getName() { return $this->name; } } Ruby equivalent class Person def set_name(name) @name = name end def get_name() @name end end What does the double at sign @@ mean, and how does it differ from a single at sign?

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  • Environment variable blank inside application

    - by Jake
    I have an environment variable that I've set in ~/.profile with the following line: export APPDIR=/path/to/dir When I log in and load up a terminal, I can verify that the variable is set: $ printenv APPDIR /path/to/dir I'm trying to access this variable from within a Qt application: QString appdir = getenv("APPDIR"); QTWARNING("dir: |" + appdir + "|"); The warning window that pops up shows me: dir: || What is going on here? Am I misunderstanding about how environment variables work in Ubuntu? This is with a C++/Qt App on Ubuntu 11.10 x86.

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  • Modify static variables while debugging in Eclipse

    - by sleske
    As an extension the the question "Modify/view static variables while debugging in Eclipse", I'd like to be able to modify static variables while debugging in Eclipse. For instance and local variables, I can just choose the variable in the "Variables" view of Eclipse, and use the context menu "Change value..." to change the value. This is not possible for arbitrary static variables, because they do not appear in the "Variables" view. What I tried: If you choose "Java / Show static variables" from the triangle menu in the "Variables" view, you can see and modify static member variables of the variables listed in the "Variables view". However, I did not find how to access a static member of a class whose instance does not appear in the "Variables view". You can of course enter a static member as an expression into the "Expression view" (using fully qualified name). Then you can see the value, but the "Expression view" does not have an option to modify the value (it does allow to modify members of an expression, but not the expression itself, even if the expression is a field). So, if I have a static variable like a boolean MyClass.disableAllBugs, is there a way to change MyClass.disableAllBugs during debugging? As an aside: I realize that even having public mutable static fields (i.e. mutable global variables) is very bad style. But some codebases have it, and then it's sometimes useful to modify it while debugging.

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  • Better use on the name of variables

    - by Cuartico
    I have a method that looks like this: Public Function NormalizeStreetAddress(country As Namespace.Country, streetAddress As Namespace.StreetAddress) _ As Namespace.StreetAddress Dim _streetAddress As New Namespace.StreetAddress = streetAddress If My.Settings.Streeteable = True Then Dim _AddressCustom As New Namespace.AddressCustom _streetAddress = _AddressCustom.NormalizeStreetAddress(country, streetAddress) End If Return _streetAddress End Function I receive a streetAddress object, but inside the method I need to use another streetAddress object which I called _streetAddress — is that following the standard? A friend of mine told me that object names such as _yourNameObject are for global variables, but I can't find info about this and I want to make this method more readable.

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  • Generalise variable usage inside code

    - by Shirish11
    I would like to know if it is a good practice to generalize variables (use single variable to store all the values). Consider simple example Strings querycre,queryins,queryup,querydel; querycre = 'Create table XYZ ...'; execute querycre ; queryins = 'Insert into XYZ ...'; execute queryins ; queryup = 'Update XYZ set ...'; execute queryup; querydel = 'Delete from XYZ ...'; execute querydel ; and Strings query; query= 'Create table XYZ ... '; execute query ; query= 'Insert into XYZ ...'; execute query ; query= 'Update XYZ set ...'; execute query ; query= 'Delete from XYZ ...'; execute query ; In first case I use 4 strings each storing data to perform the actions mentioned in their suffixes. In second case just 1 variable to store all kinds the data. Having different variables makes it easier for someone else to read and understand it better. But having too many of them makes it difficult to manage. Also does having too many variables hamper my performance?

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  • Global and local variables in my script

    - by Acorn
    I'm starting out learning javascript, and tried to write a little script that would make a grid of divs on a page. Here's the script: var tileWidth=50; var tileHeight=100; var leftPos=10; var topPos=10; var columns=10; var rows=10; var spacing=5; $('document').ready(function() { placeTiles(); }); function makeRow() { for (var i=0; i<columns; i++) { $('#canvas').append('<div class="tile" style="left:' + leftPos + 'px;top:' + topPos + 'px;"></div>'); var leftPos = leftPos + tileWidth + spacing; } } function placeTiles() { for (var i=0; i<rows; i++) { makeRow(); var topPos = topPos + tileHeight + spacing; } } At the moment, 100 <div>s get created, all with a top position of 10px and a left position of undefined (for the first <div> in the row) or NaN. What should I be doing differently? Why can't makerow() see my global leftPos variable (and all the other variables for that matter)? Thanks.

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  • Application specific environment variable settings

    - by SuperElectric
    I'm trying to work around a known bug in Ubuntu 9.10, where using the scrollbar in emacs causes text to be highlighted, and the cursor to move. This page here shows that you can fix this by setting an environment variable before launching emacs: $ GDK_NATIVE_WINDOWS=1 emacs So a lazy fix would be to alias "emacs" in my .bashrc: alias emacs="GDK_NATIVE_WINDOWS=1 emacs" This, however, has the drawback of setting this environment variable for all subsequent commands run from that shell. Is there any way to set GDK_NATIVE_WINDOWS=1 for just emacs, whenever I run emacs?

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  • Setting environment variables when executing Eclipse via Unity launcher icon

    - by Nullptr
    My question is a followup for the following: How to pin Eclipse to the Unity launcher? I created Eclipse's icon to the Unity launcher based on the selected answer at the above link. However, when I launch Eclipse via this icon, the environment variables are not properly set. I need to call . /opt/intel/bin/compilervars.sh intel64 to use Intel compiler tools in Eclipse. However, launching via the icon can't do it. Of course, running manually Eclipse on the terminal is okay. I tried to place . /opt/intel/bin/compilervars.sh intel64 on several places such as /etc/profile and /etc/bash.bashrc. But, still not working. Where is the best and correct place to call such environment setup?

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  • Initialized variables vs named constants

    - by Mike
    I'm working on a fundamental programming class in college and our textbook is "programming logic and design" by joyce farrell(spelling?) Anyhow, I'm struggling conceptually when it comes to initialized variables and named constants. Our class is focusing on pseudo-code for the time being and not one particular language so let me illustrate what I'm talking about. Let's say I am declaring a variable named "myVar" and the data type is numeric: num myVar now I want to initialize it (I don't understand this concept) starting with the number 5 num myVar = 5 how is that any different than creating a named constant?

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  • Returning a variable in a public void...

    - by James Rattray
    Hello, I'm abit new to programming Android App's, however I have come across a problem, I can't find a way to make global variables -unlike other coding like php or VB.NET, are global variables possible? If not can someone find a way (and if possible implement the way into the code I will provide below) to get a value from the variable 'songtoplay' so I can use in another Public Void... Here is the code: final Spinner hubSpinner = (Spinner) findViewById(R.id.myspinner); ArrayAdapter adapter = ArrayAdapter.createFromResource( this, R.array.colours, android.R.layout.simple_spinner_item); adapter .setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); hubSpinner.setAdapter(adapter); // hubSpinner.setOnItemSelectedListener(new OnItemSelectedListener() { public void onItemSelected(AdapterView<?> parentView, View selectedItemView, int position, long id) { //code Object ttestt = hubSpinner.getSelectedItem(); final String test2 = ttestt.toString(); Toast message1 = Toast.makeText(Textbox.this, test2, Toast.LENGTH_LONG); message1.show(); String songtoplay = test2; // Need songtoplay to be available in another 'Public Void' } public void onNothingSelected(AdapterView<?> parentView) { //Code } }); Basically, it gets the value from the Spinner 'hubSpinner' and displays it in a Toast. I then want it to return a value for string variable 'songtoplay' -or find a way to make it global or useable in another Public Void, (Which is will a button, -loading the song to be played) Please help me, Thanks alot. James

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  • Access variable value using string representing variable's name

    - by Paul Ridgway
    Hello everyone, If the title was not clear, I will try to clarify what I am asking: Imagine I have a variable called counter, I know I can see its current value by doing something like: std::cout << counter << std::endl; However, assume I have lots of variables and I don't know which I'm going to want to look at until runtime. Does anyone know a way I can fetch the value of a variable by using its name, for example: std::cout << valueOf("counter") << std::endl; I feel being able to do this might make debugging large complex projects easier. Thanks in advance for your time.

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  • C++ Access variable value using string representing variable's name

    - by Paul Ridgway
    Hello everyone, If the title was not clear, I will try to clarify what I am asking: Imagine I have a variable called counter, I know I can see its current value by doing something like: std::cout << counter << std::endl; However, assume I have lots of variables and I don't know which I'm going to want to look at until runtime. Does anyone know a way I can fetch the value of a variable by using its name, for example: std::cout << valueOf("counter") << std::endl; I feel being able to do this might make debugging large complex projects easier. Thanks in advance for your time. PS: Please do not respond with 'Google it', I have, though maybe not with the best query to get the answer I'm looking for...

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  • Change environment variables as standard user (Windows 7)

    - by SealedSun
    When clicking on "Advanced system settings", I need to login as the administrator and hence only edit the administrators environment variables (in addition to the machine wide ones). How do I edit the environment variables of a standard user? Details With the migration to Windows 7, I decided to work as a standard user instead of an unprivileged administrator. Works well so far but I encountered a tiny problem: When I try to change per user environment variables via the control panel I have to login as an administrator. But since I run that part of the control panel as the administrator I can only edit the administrators variables. How am I supposed to edit my own environment variables? Without resorting to extreme measures, such as editing the registry (as suggested in "Is there any command line tool that can be used to edit environment variables in Windows?" )

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