WORKING WITH TYPES in visual C#.net

Add Code 39 Extended in visual C#.net WORKING WITH TYPES

We now discuss a global fetching strategy setting: the maximum fetch depth. This setting controls the number of outer-joined tables NHibernate uses in a single SQL query. Consider the complete association chain from Category to Item, and from Item to Bid. The first is a many-to-many association, and the second is one-to-many; hence both associations are mapped with collection elements. If you declare outerjoin="true" for both associations (don t forget the special <many-to-many> declaration) and load a single Category, how many queries will NHibernate execute Will only the Items be eagerly fetched, or also all the Bids of each Item You probably expect a single query with an outer join operation including the CATEGORY, CATEGORY_ITEM, ITEM, and BID tables. But this isn t the case by default. NHibernate s outer join fetch behavior is controlled with the global configuration option hibernate.max_fetch_depth. If you set this to 1 (also the default), NHibernate fetches only the Category and the link entries from the CATEGORY_ITEM association table. If you set it to 2, NHibernate executes an outer join that also includes the Items in the same SQL query. Setting this option to 3 won t, as you might have

You can fine-tune your keyboard by selecting various languages and changing settings like Auto-Correction and Auto-Capitalization. You can even have your iPhone speak the Auto-Correction suggestions to you as you type. See 2: Typing Tips, Copy/Paste, and Search for keyboard options and how to use the various features.

IMPLEMENT THE CLICK EVENT HANDLER TO CREATE A NEW FORM Action 4 Create a new Form in the Click handler. Result

int main (int argc, const char *argv[]) { RetainTracker *tracker = [RetainTracker new]; // count: 1 [tracker retain]; // count: 2 NSLog (@"%d", [tracker retainCount]); [tracker retain]; // count: 3 NSLog (@"%d", [tracker retainCount]); [tracker release]; // count: 2 NSLog (@"%d", [tracker retainCount]); [tracker release]; // count: 1 NSLog (@"%d", [tracker retainCount]); [tracker retain]; // count 2 NSLog (@"%d", [tracker retainCount]); [tracker release]; // count 1 NSLog (@"%d", [tracker retainCount]); [tracker release]; // count: 0, dealloc it return (0); } // main

In every one of those cases, $_ occurs only within the curly braces of a script block. That s a good rule to remember for figuring out when it s okay to use $_.

Whoa, wait a minute. What s with that copying and not retaining You want to make copies of string arguments. A common error is to get a string from the user interface, like a text field, and use that as something s name. The strings you get from text fields are typically mutable strings and will change when the user types something new. Making a copy of the string prevents the value from changing unexpectedly. Now, what about not retaining objects There is a special case, called a retain cycle, in which reference counting breaks down. If you have an owner/owned relationship, as between Car and Engine, you want the car to retain (own) the engine but not the other way around. The engine should not retain the car it has been installed in. If the car retains the engine, and the engine retains the car, then neither reference count will go to zero, and neither will ever be cleaned up. Car s dealloc won t get called until the engine releases the car in its dealloc, and the engine s dealloc won t get called until car s dealloc releases the Engine. They just sit there, staring at each other, waiting for the other to blink. The general rule is that the owner object retains the ownee object, and not the other way around. Lucky garbage collection users don t need to worry about this case.

peril, since humans aren t typically very good at boring repetitive work. Luckily for us, computers thrive on boring and repetitive work. The first Xcode feature to help us here doesn t actually manipulate code but installs a safety net. Chose File Make Snapshot (or its handy shortcut, command-control-S) and Xcode will remember the state of your project. You re now free to edit source files and fold, spindle, and mutilate your stuff all you want. If you realize you ve made a terrible mistake, you can use the snapshots window, which you can access from File Snapshots, to recover from a previous snapshot. It s a good idea to take a snapshot before doing anything too adventurous.

float f; f = (int)1.5;

When you create a Windows Form using the Visual Studio .NET wizards, you ll automatically be provided with a container for your components and an overridden Dispose method. 7.2.2 The Control class A control is a component that is visibly represented in a window and typically responds to user input in the form of keyboard events and mouse clicks. Being visible means that a control has a specified position and size. Examples include buttons, labels, check boxes, and list boxes. The Control class extends Component with more than 300 new properties, methods, and events. Some of the more commonly used members are shown in table 7.1.

[powersView deselectAllCells]; for (NSString *power in [[self class] powers]) { if ([[villain objectForKey:kPowers] containsObject:power]) { [[powersView cellWithTag: [[[self class] powers] indexOfObject:power]] setState:NSOnState]; } }