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  • Quick Question: How can I make sure the current directory is not changed because of OpenFileDialog?

    - by pecker
    say my application is installed in C:\programfiles\xyz\ I've some setting & other data files (*.dat files) in this directory too. My application uses OpenFileDialog to open an image. Problem is that when ever user browses to some directory (say MyPictures) for an image. The current working directory of the application becomes that directory (MyPictures in this case). After user inputs the image. I do some processing over it and save some values to imagedata.dat which will be located in the path where original application is installed.(C:\programfiles\xyz here ) In my code I'm just using FileStream("imagedata.dat",...,...) without any path prefix before the filename. Problem here is that application is crashing because it is searching for imagedata.dat in 'MyPictures\imagedata.dat'. How can I avoid this?

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  • Using the JNotify library, how can you tell if a deleted file was a file or a directory?

    - by Moeri
    For those unfamiliar with JNotify, this is a library which provides an easy way to monitor events in a directory. For instance, when a file gets deleted in the selected folder, the method "fileDeleted" gets called, along with a few parameters. Here's an example of the fileDeleted method: public void fileDeleted(int wd, String rootPath, String name) { print("deleted " + rootPath + " : " + name); } Now, I would like to know if the deleted file was a file or directory. My usual approach is to create a new File object with the given path, and use the methods isFile() and isDirectory() However, since this file is already deleted, these methods always return false. So here's my concrete question: I have the path to a deleted file or directory, how can I tell wether it was a file or a directory? Is there a workaround to this? What's the best practice to do here? Thank you in advance.

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  • Maximum number of files in one ext3 directory while still getting acceptable performance?

    - by knorv
    I have an application writing to an ext3 directory which over time has grown to roughly three million files. Needless to say, reading the file listing of this directory is unbearably slow. I don't blame ext3. The proper solution would have been to let the application code write to sub-directories such as ./a/b/c/abc.ext rather than using only ./abc.ext. I'm changing to such a sub-directory structure and my question is simply: roughly how many files should I expect to store in one ext3 directory while still getting acceptable performance? What's your experience? Or in other words; assuming that I need to store three million files in the structure, how many levels deep should the ./a/b/c/abc.ext structure be? Obviously this is a question that cannot be answered exactly, but I'm looking for a ball park estimate.

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  • How to mock/stub a directory of files and their contents using RSpec?

    - by John Topley
    A while ago I asked "How to test obtaining a list of files within a directory using RSpec?" and although I got a couple of useful answers, I'm still stuck, hence a new question with some more detail about what I'm trying to do. I'm writing my first RubyGem. It has a module that contains a class method that returns an array containing a list of non-hidden files within a specified directory. Like this: files = Foo.bar :directory => './public' The array also contains an element that represents metadata about the files. This is actually a hash of hashes generated from the contents of the files, the idea being that changing even a single file changes the hash. I've written my pending RSpec examples, but I really have no idea how to implement them: it "should compute a hash of the files within the specified directory" it "shouldn't include hidden files or directories within the specified directory" it "should compute a different hash if the content of a file changes" I really don't want to have the tests dependent on real files acting as fixtures. How can I mock or stub the files and their contents? The gem implementation will use Find.find, but as one of the answers to my other question said, I don't need to test the library. I really have no idea how to write these specs, so any help much appreciated!

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  • Visual Studio as Code Browser : How to preserve the directory structure?

    - by claws
    Hello, I've downloaded source of an opensource C++ project. It is a Linux project. As Visual Studio is my favorite IDE I want to use it to browse & study the code. I created an empty C++ project and now want to add the source code to Solution explorer. How can I add the directory structure to "Solution Explorer". Dropping the root folder of source code on the project in solution explorer is not working. Its just adding the files to the project but directory structure is lost. Is there any way to preserve the directory structure? I do not want to recreate the directory structure manually.

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  • Do I need something more to run NUnit under any directory?

    - by prosseek
    I have NUnit installed at this directory. C:\Program Files\NUnit 2.5.5\bin\net-2.0 When I try to run my unit test (mut.dll) in some random directory. I get the following error. I have to copy the mut.dll under the NUnit directory in order to run it. ProcessModel: Default DomainUsage: Single Execution Runtime: net-2.0 Could not load file or assembly 'nunit.framework, Version=2.5.5.10112, Culture=n eutral, PublicKeyToken=96d09a1eb7f44a77' or one of its dependencies. The system cannot find the file specified. What's wrong? Is there anything that I have to configure to run NUNit under any directory?

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  • Use registry to startup a program, and also change the current working directory?

    - by Joel
    I am trying to start a program I made in this directory: C:\example\example.exe -someargument when the computer starts up. I am attempting to use this registry key: HKEY_LOCAL_MACHINE/Software/Microsoft/Windows/CurrentVersion/Run with the key being: Name: example Type: REG_SZ Data: "C:\example\example.exe -someargument" But my program also needs files from the directory C:\example but can't find them since the current working directory is different. Is is possible to do something like this in the registry key value "cd C:\example\; example.exe -someargument" so that it will change the directory? Or is there a better solution? Thanks!

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  • Add collison detection to enemy sprites?

    - by xBroak
    i'd like to add the same collision detection used by the player sprite to the enemy sprites or 'creeps' ive added all the relevant code I can see yet collisons are still not being detected and handled, please find below the class, I have no idea what is wrong currently, the list of walls to collide with is 'wall_list' import pygame import pauseScreen as dm import re from pygame.sprite import Sprite from pygame import Rect, Color from random import randint, choice from vec2d import vec2d from simpleanimation import SimpleAnimation import displattxt black = (0,0,0) white = (255,255,255) blue = (0,0,255) green = (101,194,151) global currentEditTool currentEditTool = "Tree" global editMap editMap = False open('MapMaker.txt', 'w').close() def draw_background(screen, tile_img): screen.fill(black) img_rect = tile_img.get_rect() global rect rect = img_rect nrows = int(screen.get_height() / img_rect.height) + 1 ncols = int(screen.get_width() / img_rect.width) + 1 for y in range(nrows): for x in range(ncols): img_rect.topleft = (x * img_rect.width, y * img_rect.height) screen.blit(tile_img, img_rect) def changeTool(): if currentEditTool == "Tree": None elif currentEditTool == "Rock": None def pauseGame(): red = 255, 0, 0 green = 0,255, 0 blue = 0, 0,255 screen.fill(black) pygame.display.update() if editMap == False: choose = dm.dumbmenu(screen, [ 'Resume', 'Enable Map Editor', 'Quit Game'], 64,64,None,32,1.4,green,red) if choose == 0: print("hi") elif choose ==1: global editMap editMap = True elif choose ==2: print("bob") elif choose ==3: print("bob") elif choose ==4: print("bob") else: None else: choose = dm.dumbmenu(screen, [ 'Resume', 'Disable Map Editor', 'Quit Game'], 64,64,None,32,1.4,green,red) if choose == 0: print("Resume") elif choose ==1: print("Dis ME") global editMap editMap = False elif choose ==2: print("bob") elif choose ==3: print("bob") elif choose ==4: print("bob") else: None class Wall(pygame.sprite.Sprite): # Constructor function def __init__(self,x,y,width,height): pygame.sprite.Sprite.__init__(self) self.image = pygame.Surface([width, height]) self.image.fill(green) self.rect = self.image.get_rect() self.rect.y = y self.rect.x = x class insertTree(pygame.sprite.Sprite): def __init__(self,x,y,width,height, typ): pygame.sprite.Sprite.__init__(self) self.image = pygame.image.load("images/map/tree.png").convert() self.image.set_colorkey(white) self.rect = self.image.get_rect() self.rect.y = y self.rect.x = x class insertRock(pygame.sprite.Sprite): def __init__(self,x,y,width,height, typ): pygame.sprite.Sprite.__init__(self) self.image = pygame.image.load("images/map/rock.png").convert() self.image.set_colorkey(white) self.rect = self.image.get_rect() self.rect.y = y self.rect.x = x class Creep(pygame.sprite.Sprite): """ A creep sprite that bounces off walls and changes its direction from time to time. """ change_x=0 change_y=0 def __init__( self, screen, creep_image, explosion_images, field, init_position, init_direction, speed): """ Create a new Creep. screen: The screen on which the creep lives (must be a pygame Surface object, such as pygame.display) creep_image: Image (surface) object for the creep explosion_images: A list of image objects for the explosion animation. field: A Rect specifying the 'playing field' boundaries. The Creep will bounce off the 'walls' of this field. init_position: A vec2d or a pair specifying the initial position of the creep on the screen. init_direction: A vec2d or a pair specifying the initial direction of the creep. Must have an angle that is a multiple of 45 degres. speed: Creep speed, in pixels/millisecond (px/ms) """ Sprite.__init__(self) self.screen = screen self.speed = speed self.field = field self.rect = creep_image.get_rect() # base_image holds the original image, positioned to # angle 0. # image will be rotated. # self.base_image = creep_image self.image = self.base_image self.explosion_images = explosion_images # A vector specifying the creep's position on the screen # self.pos = vec2d(init_position) # The direction is a normalized vector # self.direction = vec2d(init_direction).normalized() self.state = Creep.ALIVE self.health = 15 def is_alive(self): return self.state in (Creep.ALIVE, Creep.EXPLODING) def changespeed(self,x,y): self.change_x+=x self.change_y+=y def update(self, time_passed, walls): """ Update the creep. time_passed: The time passed (in ms) since the previous update. """ if self.state == Creep.ALIVE: # Maybe it's time to change the direction ? # self._change_direction(time_passed) # Make the creep point in the correct direction. # Since our direction vector is in screen coordinates # (i.e. right bottom is 1, 1), and rotate() rotates # counter-clockwise, the angle must be inverted to # work correctly. # self.image = pygame.transform.rotate( self.base_image, -self.direction.angle) # Compute and apply the displacement to the position # vector. The displacement is a vector, having the angle # of self.direction (which is normalized to not affect # the magnitude of the displacement) # displacement = vec2d( self.direction.x * self.speed * time_passed, self.direction.y * self.speed * time_passed) self.pos += displacement # When the image is rotated, its size is changed. # We must take the size into account for detecting # collisions with the walls. # self.image_w, self.image_h = self.image.get_size() bounds_rect = self.field.inflate( -self.image_w, -self.image_h) if self.pos.x < bounds_rect.left: self.pos.x = bounds_rect.left self.direction.x *= -1 elif self.pos.x > bounds_rect.right: self.pos.x = bounds_rect.right self.direction.x *= -1 elif self.pos.y < bounds_rect.top: self.pos.y = bounds_rect.top self.direction.y *= -1 elif self.pos.y > bounds_rect.bottom: self.pos.y = bounds_rect.bottom self.direction.y *= -1 # collision detection old_x=bounds_rect.left new_x=old_x+self.direction.x bounds_rect.left = new_x # hit a wall? collide = pygame.sprite.spritecollide(self, walls, False) if collide: # yes bounds_rect.left=old_x old_y=self.pos.y new_y=old_y+self.direction.y self.pos.y = new_y collide = pygame.sprite.spritecollide(self, walls, False) if collide: # yes self.pos.y=old_y elif self.state == Creep.EXPLODING: if self.explode_animation.active: self.explode_animation.update(time_passed) else: self.state = Creep.DEAD self.kill() elif self.state == Creep.DEAD: pass #------------------ PRIVATE PARTS ------------------# # States the creep can be in. # # ALIVE: The creep is roaming around the screen # EXPLODING: # The creep is now exploding, just a moment before dying. # DEAD: The creep is dead and inactive # (ALIVE, EXPLODING, DEAD) = range(3) _counter = 0 def _change_direction(self, time_passed): """ Turn by 45 degrees in a random direction once per 0.4 to 0.5 seconds. """ self._counter += time_passed if self._counter > randint(400, 500): self.direction.rotate(45 * randint(-1, 1)) self._counter = 0 def _point_is_inside(self, point): """ Is the point (given as a vec2d) inside our creep's body? """ img_point = point - vec2d( int(self.pos.x - self.image_w / 2), int(self.pos.y - self.image_h / 2)) try: pix = self.image.get_at(img_point) return pix[3] > 0 except IndexError: return False def _decrease_health(self, n): """ Decrease my health by n (or to 0, if it's currently less than n) """ self.health = max(0, self.health - n) if self.health == 0: self._explode() def _explode(self): """ Starts the explosion animation that ends the Creep's life. """ self.state = Creep.EXPLODING pos = ( self.pos.x - self.explosion_images[0].get_width() / 2, self.pos.y - self.explosion_images[0].get_height() / 2) self.explode_animation = SimpleAnimation( self.screen, pos, self.explosion_images, 100, 300) global remainingCreeps remainingCreeps-=1 if remainingCreeps == 0: print("all dead") def draw(self): """ Blit the creep onto the screen that was provided in the constructor. """ if self.state == Creep.ALIVE: # The creep image is placed at self.pos. To allow for # smooth movement even when the creep rotates and the # image size changes, its placement is always # centered. # self.draw_rect = self.image.get_rect().move( self.pos.x - self.image_w / 2, self.pos.y - self.image_h / 2) self.screen.blit(self.image, self.draw_rect) # The health bar is 15x4 px. # health_bar_x = self.pos.x - 7 health_bar_y = self.pos.y - self.image_h / 2 - 6 self.screen.fill( Color('red'), (health_bar_x, health_bar_y, 15, 4)) self.screen.fill( Color('green'), ( health_bar_x, health_bar_y, self.health, 4)) elif self.state == Creep.EXPLODING: self.explode_animation.draw() elif self.state == Creep.DEAD: pass def mouse_click_event(self, pos): """ The mouse was clicked in pos. """ if self._point_is_inside(vec2d(pos)): self._decrease_health(3) #begin new player class Player(pygame.sprite.Sprite): change_x=0 change_y=0 frame = 0 def __init__(self,x,y): pygame.sprite.Sprite.__init__(self) # LOAD PLATER IMAGES # Set height, width self.images = [] for i in range(1,17): img = pygame.image.load("images/player/" + str(i)+".png").convert() #player images img.set_colorkey(white) self.images.append(img) self.image = self.images[0] self.rect = self.image.get_rect() self.rect.y = y self.rect.x = x self.health = 15 self.image_w, self.image_h = self.image.get_size() health_bar_x = self.rect.x - 7 health_bar_y = self.rect.y - self.image_h / 2 - 6 screen.fill( Color('red'), (health_bar_x, health_bar_y, 15, 4)) screen.fill( Color('green'), ( health_bar_x, health_bar_y, self.health, 4)) def changespeed(self,x,y): self.change_x+=x self.change_y+=y def _decrease_health(self, n): """ Decrease my health by n (or to 0, if it's currently less than n) """ self.health = max(0, self.health - n) if self.health == 0: self._explode() def update(self,walls): # collision detection old_x=self.rect.x new_x=old_x+self.change_x self.rect.x = new_x # hit a wall? collide = pygame.sprite.spritecollide(self, walls, False) if collide: # yes self.rect.x=old_x old_y=self.rect.y new_y=old_y+self.change_y self.rect.y = new_y collide = pygame.sprite.spritecollide(self, walls, False) if collide: # yes self.rect.y=old_y # right to left if self.change_x < 0: self.frame += 1 if self.frame > 3*4: self.frame = 0 # Grab the image, divide by 4 # every 4 frames. self.image = self.images[self.frame//4] # Move left to right. # images 4...7 instead of 0...3. if self.change_x > 0: self.frame += 1 if self.frame > 3*4: self.frame = 0 self.image = self.images[self.frame//4+4] if self.change_y > 0: self.frame += 1 if self.frame > 3*4: self.frame = 0 self.image = self.images[self.frame//4+4+4] if self.change_y < 0: self.frame += 1 if self.frame > 3*4: self.frame = 0 self.image = self.images[self.frame//4+4+4+4] score = 0 # initialize pyGame pygame.init() # 800x600 sized screen global screen screen = pygame.display.set_mode([800, 600]) screen.fill(black) #bg_tile_img = pygame.image.load('images/map/grass.png').convert_alpha() #draw_background(screen, bg_tile_img) #pygame.display.flip() # Set title pygame.display.set_caption('Test') #background = pygame.Surface(screen.get_size()) #background = background.convert() #background.fill(black) # Create the player player = Player( 50,50 ) player.rect.x=50 player.rect.y=50 movingsprites = pygame.sprite.RenderPlain() movingsprites.add(player) # Make the walls. (x_pos, y_pos, width, height) global wall_list wall_list=pygame.sprite.RenderPlain() wall=Wall(0,0,10,600) # left wall wall_list.add(wall) wall=Wall(10,0,790,10) # top wall wall_list.add(wall) #wall=Wall(10,200,100,10) # poke wall wall_list.add(wall) wall=Wall(790,0,10,600) #(x,y,thickness, height) wall_list.add(wall) wall=Wall(10,590,790,10) #(x,y,thickness, height) wall_list.add(wall) f = open('MapMaker.txt') num_lines = sum(1 for line in f) print(num_lines) lineCount = 0 with open("MapMaker.txt") as infile: for line in infile: f = open('MapMaker.txt') print(line) coords = line.split(',') #print(coords[0]) #print(coords[1]) #print(coords[2]) #print(coords[3]) #print(coords[4]) if "tree" in line: print("tree in") wall=insertTree(int(coords[0]),int(coords[1]), int(coords[2]),int(coords[3]),coords[4]) wall_list.add(wall) elif "rock" in line: print("rock in") wall=insertRock(int(coords[0]),int(coords[1]), int(coords[2]),int(coords[3]),coords[4] ) wall_list.add(wall) width = 20 height = 540 height = height - 48 for i in range(0,23): width = width + 32 name = insertTree(width,540,790,10,"tree") #wall_list.add(name) name = insertTree(width,height,690,10,"tree") #wall_list.add(name) CREEP_SPAWN_TIME = 200 # frames creep_spawn = CREEP_SPAWN_TIME clock = pygame.time.Clock() bg_tile_img = pygame.image.load('images/map/grass.png').convert() img_rect = bg_tile_img FIELD_RECT = Rect(50, 50, 700, 500) CREEP_FILENAMES = [ 'images/player/1.png', 'images/player/1.png', 'images/player/1.png'] N_CREEPS = 3 creep_images = [ pygame.image.load(filename).convert_alpha() for filename in CREEP_FILENAMES] explosion_img = pygame.image.load('images/map/tree.png').convert_alpha() explosion_images = [ explosion_img, pygame.transform.rotate(explosion_img, 90)] creeps = pygame.sprite.RenderPlain() done = False #bg_tile_img = pygame.image.load('images/map/grass.png').convert() #draw_background(screen, bg_tile_img) totalCreeps = 0 remainingCreeps = 3 while done == False: creep_images = pygame.image.load("images/player/1.png").convert() creep_images.set_colorkey(white) draw_background(screen, bg_tile_img) if len(creeps) != N_CREEPS: if totalCreeps < N_CREEPS: totalCreeps = totalCreeps + 1 print(totalCreeps) creeps.add( Creep( screen=screen, creep_image=creep_images, explosion_images=explosion_images, field=FIELD_RECT, init_position=( randint(FIELD_RECT.left, FIELD_RECT.right), randint(FIELD_RECT.top, FIELD_RECT.bottom)), init_direction=(choice([-1, 1]), choice([-1, 1])), speed=0.01)) for creep in creeps: creep.update(60,wall_list) creep.draw() for event in pygame.event.get(): if event.type == pygame.QUIT: done=True if event.type == pygame.KEYDOWN: if event.key == pygame.K_LEFT: player.changespeed(-2,0) creep.changespeed(-2,0) if event.key == pygame.K_RIGHT: player.changespeed(2,0) creep.changespeed(2,0) if event.key == pygame.K_UP: player.changespeed(0,-2) creep.changespeed(0,-2) if event.key == pygame.K_DOWN: player.changespeed(0,2) creep.changespeed(0,2) if event.key == pygame.K_ESCAPE: pauseGame() if event.key == pygame.K_1: global currentEditTool currentEditTool = "Tree" changeTool() if event.key == pygame.K_2: global currentEditTool currentEditTool = "Rock" changeTool() if event.type == pygame.KEYUP: if event.key == pygame.K_LEFT: player.changespeed(2,0) creep.changespeed(2,0) if event.key == pygame.K_RIGHT: player.changespeed(-2,0) creep.changespeed(-2,0) if event.key == pygame.K_UP: player.changespeed(0,2) creep.changespeed(0,2) if event.key == pygame.K_DOWN: player.changespeed(0,-2) creep.changespeed(0,-2) if event.type == pygame.MOUSEBUTTONDOWN and pygame.mouse.get_pressed()[0]: for creep in creeps: creep.mouse_click_event(pygame.mouse.get_pos()) if editMap == True: x,y = pygame.mouse.get_pos() if currentEditTool == "Tree": name = insertTree(x-10,y-25, 10 , 10, "tree") wall_list.add(name) wall_list.draw(screen) f = open('MapMaker.txt', "a+") image = pygame.image.load("images/map/tree.png").convert() screen.blit(image, (30,10)) pygame.display.flip() f.write(str(x) + "," + str(y) + ",790,10, tree\n") #f.write("wall=insertTree(" + str(x) + "," + str(y) + ",790,10)\nwall_list.add(wall)\n") elif currentEditTool == "Rock": name = insertRock(x-10,y-25, 10 , 10,"rock") wall_list.add(name) wall_list.draw(screen) f = open('MapMaker.txt', "a+") f.write(str(x) + "," + str(y) + ",790,10,rock\n") #f.write("wall=insertRock(" + str(x) + "," + str(y) + ",790,10)\nwall_list.add(wall)\n") else: None #pygame.display.flip() player.update(wall_list) movingsprites.draw(screen) wall_list.draw(screen) pygame.display.flip() clock.tick(60) pygame.quit()

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  • StreamInsight 2.1, meet LINQ

    - by Roman Schindlauer
    Someone recently called LINQ “magic” in my hearing. I leapt to LINQ’s defense immediately. Turns out some people don’t realize “magic” is can be a pejorative term. I thought LINQ needed demystification. Here’s your best demystification resource: http://blogs.msdn.com/b/mattwar/archive/2008/11/18/linq-links.aspx. I won’t repeat much of what Matt Warren says in his excellent series, but will talk about some core ideas and how they affect the 2.1 release of StreamInsight. Let’s tell the story of a LINQ query. Compile time It begins with some code: IQueryable<Product> products = ...; var query = from p in products             where p.Name == "Widget"             select p.ProductID; foreach (int id in query) {     ... When the code is compiled, the C# compiler (among other things) de-sugars the query expression (see C# spec section 7.16): ... var query = products.Where(p => p.Name == "Widget").Select(p => p.ProductID); ... Overload resolution subsequently binds the Queryable.Where<Product> and Queryable.Select<Product, int> extension methods (see C# spec sections 7.5 and 7.6.5). After overload resolution, the compiler knows something interesting about the anonymous functions (lambda syntax) in the de-sugared code: they must be converted to expression trees, i.e.,“an object structure that represents the structure of the anonymous function itself” (see C# spec section 6.5). The conversion is equivalent to the following rewrite: ... var prm1 = Expression.Parameter(typeof(Product), "p"); var prm2 = Expression.Parameter(typeof(Product), "p"); var query = Queryable.Select<Product, int>(     Queryable.Where<Product>(         products,         Expression.Lambda<Func<Product, bool>>(Expression.Property(prm1, "Name"), prm1)),         Expression.Lambda<Func<Product, int>>(Expression.Property(prm2, "ProductID"), prm2)); ... If the “products” expression had type IEnumerable<Product>, the compiler would have chosen the Enumerable.Where and Enumerable.Select extension methods instead, in which case the anonymous functions would have been converted to delegates. At this point, we’ve reduced the LINQ query to familiar code that will compile in C# 2.0. (Note that I’m using C# snippets to illustrate transformations that occur in the compiler, not to suggest a viable compiler design!) Runtime When the above program is executed, the Queryable.Where method is invoked. It takes two arguments. The first is an IQueryable<> instance that exposes an Expression property and a Provider property. The second is an expression tree. The Queryable.Where method implementation looks something like this: public static IQueryable<T> Where<T>(this IQueryable<T> source, Expression<Func<T, bool>> predicate) {     return source.Provider.CreateQuery<T>(     Expression.Call(this method, source.Expression, Expression.Quote(predicate))); } Notice that the method is really just composing a new expression tree that calls itself with arguments derived from the source and predicate arguments. Also notice that the query object returned from the method is associated with the same provider as the source query. By invoking operator methods, we’re constructing an expression tree that describes a query. Interestingly, the compiler and operator methods are colluding to construct a query expression tree. The important takeaway is that expression trees are built in one of two ways: (1) by the compiler when it sees an anonymous function that needs to be converted to an expression tree, and; (2) by a query operator method that constructs a new queryable object with an expression tree rooted in a call to the operator method (self-referential). Next we hit the foreach block. At this point, the power of LINQ queries becomes apparent. The provider is able to determine how the query expression tree is evaluated! The code that began our story was intentionally vague about the definition of the “products” collection. Maybe it is a queryable in-memory collection of products: var products = new[]     { new Product { Name = "Widget", ProductID = 1 } }.AsQueryable(); The in-memory LINQ provider works by rewriting Queryable method calls to Enumerable method calls in the query expression tree. It then compiles the expression tree and evaluates it. It should be mentioned that the provider does not blindly rewrite all Queryable calls. It only rewrites a call when its arguments have been rewritten in a way that introduces a type mismatch, e.g. the first argument to Queryable.Where<Product> being rewritten as an expression of type IEnumerable<Product> from IQueryable<Product>. The type mismatch is triggered initially by a “leaf” expression like the one associated with the AsQueryable query: when the provider recognizes one of its own leaf expressions, it replaces the expression with the original IEnumerable<> constant expression. I like to think of this rewrite process as “type irritation” because the rewritten leaf expression is like a foreign body that triggers an immune response (further rewrites) in the tree. The technique ensures that only those portions of the expression tree constructed by a particular provider are rewritten by that provider: no type irritation, no rewrite. Let’s consider the behavior of an alternative LINQ provider. If “products” is a collection created by a LINQ to SQL provider: var products = new NorthwindDataContext().Products; the provider rewrites the expression tree as a SQL query that is then evaluated by your favorite RDBMS. The predicate may ultimately be evaluated using an index! In this example, the expression associated with the Products property is the “leaf” expression. StreamInsight 2.1 For the in-memory LINQ to Objects provider, a leaf is an in-memory collection. For LINQ to SQL, a leaf is a table or view. When defining a “process” in StreamInsight 2.1, what is a leaf? To StreamInsight a leaf is logic: an adapter, a sequence, or even a query targeting an entirely different LINQ provider! How do we represent the logic? Remember that a standing query may outlive the client that provisioned it. A reference to a sequence object in the client application is therefore not terribly useful. But if we instead represent the code constructing the sequence as an expression, we can host the sequence in the server: using (var server = Server.Connect(...)) {     var app = server.Applications["my application"];     var source = app.DefineObservable(() => Observable.Range(0, 10, Scheduler.NewThread));     var query = from i in source where i % 2 == 0 select i; } Example 1: defining a source and composing a query Let’s look in more detail at what’s happening in example 1. We first connect to the remote server and retrieve an existing app. Next, we define a simple Reactive sequence using the Observable.Range method. Notice that the call to the Range method is in the body of an anonymous function. This is important because it means the source sequence definition is in the form of an expression, rather than simply an opaque reference to an IObservable<int> object. The variation in Example 2 fails. Although it looks similar, the sequence is now a reference to an in-memory observable collection: var local = Observable.Range(0, 10, Scheduler.NewThread); var source = app.DefineObservable(() => local); // can’t serialize ‘local’! Example 2: error referencing unserializable local object The Define* methods support definitions of operator tree leaves that target the StreamInsight server. These methods all have the same basic structure. The definition argument is a lambda expression taking between 0 and 16 arguments and returning a source or sink. The method returns a proxy for the source or sink that can then be used for the usual style of LINQ query composition. The “define” methods exploit the compile-time C# feature that converts anonymous functions into translatable expression trees! Query composition exploits the runtime pattern that allows expression trees to be constructed by operators taking queryable and expression (Expression<>) arguments. The practical upshot: once you’ve Defined a source, you can compose LINQ queries in the familiar way using query expressions and operator combinators. Notably, queries can be composed using pull-sequences (LINQ to Objects IQueryable<> inputs), push sequences (Reactive IQbservable<> inputs), and temporal sequences (StreamInsight IQStreamable<> inputs). You can even construct processes that span these three domains using “bridge” method overloads (ToEnumerable, ToObservable and To*Streamable). Finally, the targeted rewrite via type irritation pattern is used to ensure that StreamInsight computations can leverage other LINQ providers as well. Consider the following example (this example depends on Interactive Extensions): var source = app.DefineEnumerable((int id) =>     EnumerableEx.Using(() =>         new NorthwindDataContext(), context =>             from p in context.Products             where p.ProductID == id             select p.ProductName)); Within the definition, StreamInsight has no reason to suspect that it ‘owns’ the Queryable.Where and Queryable.Select calls, and it can therefore defer to LINQ to SQL! Let’s use this source in the context of a StreamInsight process: var sink = app.DefineObserver(() => Observer.Create<string>(Console.WriteLine)); var query = from name in source(1).ToObservable()             where name == "Widget"             select name; using (query.Bind(sink).Run("process")) {     ... } When we run the binding, the source portion which filters on product ID and projects the product name is evaluated by SQL Server. Outside of the definition, responsibility for evaluation shifts to the StreamInsight server where we create a bridge to the Reactive Framework (using ToObservable) and evaluate an additional predicate. It’s incredibly easy to define computations that span multiple domains using these new features in StreamInsight 2.1! Regards, The StreamInsight Team

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  • With Apache, is it possible to generate a directory listing for a non-folder URL?

    - by William Denniss
    Apache allows you to create a directory list (when configured) if you visit a folder with no index.html. What I want to know is, is it possible to get that same list but at a different URL? I'm already using index.html and want to keep it that way. i.e., this is what I'm looking for: http://example.com/blar/ - loads my index.html page (don't want this to change) http://example.com/blar/directory_list (I want this url to render the apache directory list instead)

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  • How can I bind mount a directory with a space in it?

    - by chris
    I have a drive mounted at /media/ that contains a directory with a space in the name - let's call it "My Stuff". I would like to bind mount it to "My Stuff" in my home directory. I tried the following in fstab, but all attempts to mount resulted in a syntax error: /media/My\ Stuff /home/me/My\ Stuff none bind "/media/My\ Stuff" "/home/me/My\ Stuff" none bind "/media/My Stuff" "/home/me/My Stuff" none bind Is there a way to do this?

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  • How can I force a merge of all WAL files in pg_xlog back into my base "data" directory?

    - by Zac B
    Question: Is there a way to tell Postgres (9.2) to "merge all WAL files in pg_xlog back into the non-WAL data files, and then delete all WAL files successfully merged?" I would like to be able to "force" this operation; i.e. checkpoint_segments or archiving settings should be ignored. The filesystem WAL buffer (pg_xlog) directory should be emptied, or nearly emptied. It's fine if some or all of the space consumed by the pg_xlog directory is then consumed by the data directory; our DBA has asked for WAL database backups without any backlogged WALs, but space consumption is not a concern. Having near-zero WAL activity during this operation is a fine constraint. I can ensure that the database server is either shut down or not connectible (zero user-generated transaction load) during this process. Essentially, I'd like Postgres to ignore archiving/checkpoint retention policies temporarily, and flush all WAL activity to the core database files, leaving pg_xlog in the same state as if the database were recently created--with very few WAL files. What I've Tried: I know that the pg_basebackup utility performs something like this (it generates an almost-all-WALs-merged copy of a Postgres instance's data directory), but we aren't ready to use it on all our systems yet, as we are still testing replication settings; I'm hoping for a more short-term solution. I've tried issuing CHECKPOINT commands, but they just recycle one WAL file and replace it with another (that is, if they do anything at all; if I issue them during database idle time, they do nothing). pg_switch_xlog() similarly just forces a switch to the next log segment; it doesn't flush all queued/buffered segments. I've also played with the pg_resetxlog utility. That utility sort of does what I want, but all of its usage docs seem to indicate that it destroys (rather than flushing out of the transaction log and into the main data files) some or all of the WAL data. Is that impression accurate? If not, can I use pg_resetxlog during a zero-WAL-activity period to force a flush of all queued WAL data to non-WAL data? If the answer to that is negative, how can I achieve this goal? Thanks!

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  • Where should the web server root directory go in linux?

    - by Xeoncross
    I see that Apache and Nginx both use var/www as their web root - but that directory is not covered in the Filesystem Hierarchy Standard. I also see some servers with the web root in the /home/username/www directory. So where does the web root go? Or rather, where should it go most of the time for the common web server?

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  • When I click the address bar folder/directory buttons, is there a way to make them open in a new window?

    - by galacticninja
    In Windows XP, installing the software 'Explorer Breadcrumbs' allows me to have an address bar similar to Windows 7 (directories are displayed as buttons that you can click to go to). With Explorer Breadcrumbs in Windows XP, I can open a directory in the address bar in a new window by ctrl-clicking or middle clicking the directory button. Is there a way to have this same functionality in Windows 7?

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  • How do I prevent apache from serving the .git directory?

    - by Shoan
    I have started using git for deployment of websites for testing. How do I prevent apache from serving the .git directory contents? I tried <Directorymatch "^/.*/\.svn/"> Order deny,allow Deny from all </Directorymatch> with no success. I know that I can create a .htaccess file in each .git directory and deny access, but I wanted something I could put into the main config file that makes this global across all websites.

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  • Is it possible for a directory to get unlinked while its contained files remain?

    - by Walkerneo
    I used to wonder why deleting directories via PHP or shell wasn't as easy as it was in Windows with just clicking delete. I realize now that deleting is simply unlinking files from the file allocation table, so to delete a directory, you must unlink all the files inside it. Is it ever possible for the directory's entry to be removed, but not those of the files inside it? Do operating systems periodically check for files that can't be reached in the file system?

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