Tutorial by Examples: ch

foo = "bar" foo[0] = "c" # Error Immutable variable value can not be changed once they are created.

foreach varlist1 list1 ?varlist2 list2 ...? body foreach is a powerful control structure that allows looping over a list or multiple lists. set alpha [list a b c d e f] foreach {key} $alpha { puts "key: $key" } Multiple variable names may be specified. set alphaindexes [list a ...

There are three ways to reopen a Singleton Class Using class_eval on a singleton class. Using class << block. Using def to define a method on the object's singleton class directly class Example end Example.singleton_class.class_eval do def foo :foo end end Example.fo...

$productFound = ($product->getId() !== null)

To view difference between two branch git diff <branch1>..<branch2> To view difference between two branch git diff <commitId1>..<commitId2> To view diff with current branch git diff <branch/commitId> To view summary of changes git diff --stat <branch/com...

The revert command allows discarding unwanted uncommitted changes. Reverting changes to a single file. hg revert example.c Reverting all changes. This will discard all changes not just the current directory. hg revert --all hg will output which files were reverted. reverting exa...

During mousemove you get flooded with 30 mouse events per second. You might not be able to redraw your drawings at 30 times per second. Even if you can, you're probably wasting computing power by drawing when the browser is not ready to draw (wasted == across display refresh cycles). Therefore it m...

A common and task of someone using the Linux Command Line (shell) is to search for files/directories with a certain name or containing certain text. There are 2 commands you should familiarise yourself with in order to accomplish this: Find files by name find /var/www -name '*.css' This will...

The example Checking a string for unwanted characters, describes how to test and reject strings that don't meet certain criteria. Obviously, rejecting input outright is not always possible, and sometimes you just have to make do with what you receive. In these cases, a cautious developer will attemp...

Launch debug by clicking on the "beetle" icon: Debug window is now waiting instructions for next step: You can go to the next step by clicking F9 in the debug window or by clicking on the green arrow:

While Python has an assert statement, the Python unit testing framework has better assertions specialized for tests: they are more informative on failures, and do not depend on the execution's debug mode. Perhaps the simplest assertion is assertTrue, which can be used like this: import unittest ...

CREATE TABLE XtoY ( # No surrogate id for this table x_id MEDIUMINT UNSIGNED NOT NULL, -- For JOINing to one table y_id MEDIUMINT UNSIGNED NOT NULL, -- For JOINing to the other table # Include other fields specific to the 'relation' PRIMARY KEY(x_id, y_id), --...

To add a child view controller: - (void)displayContentController:(UIViewController *)vc { [self addChildViewController:vc]; vc.view.frame = self.view.frame; [self.view addSubview:vc.view]; [vc didMoveToParentViewController:self]; } To remove a child view controller: - (void)hid...

index() returns first index of the matching value. Remember that arrays are zero-indexed. my_array = array('i', [1,2,3,4,5]) print(my_array.index(5)) # 5 my_array = array('i', [1,2,3,3,5]) print(my_array.index(3)) # 3 Note in that second example that only one index was returned, even though...

count() will return the number of times and element appears in an array. In the following example we see that the value 3 occurs twice. my_array = array('i', [1,2,3,3,5]) my_array.count(3) # 2

You are able to append a string to a character array using fromstring() my_char_array = array('c', ['g','e','e','k']) my_char_array.fromstring("stuff") print(my_char_array) #array('c', 'geekstuff')

If you are using library that contains (for example) AwesomeViewController with a wrong status bar color you can try this: let awesomeViewController = AwesomeViewController() awesomeViewController.navigationBar.barStyle = .blackTranslucent // or other style

When writing macros that expand into forms that might involve grouping, it is worthwhile spending some time considering what grouping construction to expand into. For definition style forms, for instance, a define-widget macro that will usually appear as a top-level form, and that several defuns, d...

2005 The following iterates over the characters of the string s. It works similarly for looping over the elements of an array or a set, so long as the type of the loop-control variable (c, in this example) matches the element type of the value being iterated. program ForLoopOnString; {$APPTYPE ...

const CACHE_TAG_NAMESPACE_MODULE = "YOUR_MODULES_CACHE_TAGS"; $cacheGroup = 'namespace_module'; $useCache = Mage::app()->useCache($cacheGroup); if (true === $useCache) { $cacheId = 'unique_name'; if ($cacheContent = Mage::app()->loadCache($cacheId)) { $html ...