20,741
edits
Howto:Understand Namespaces and Methods: Difference between revisions
Jump to navigation
Jump to search
m
Howto:Understand Namespaces and Methods (view source)
Revision as of 10:35, 23 December 2011
, 23 December 2011no edit summary
mNo edit summary |
|||
| Line 16: | Line 16: | ||
house3.bath | house3.bath | ||
Here, houseX is the enclosing namespace/context, i.e. "bath" is a member or "field" of the namespace. | |||
Basically, namespaces make it possible to have identically named variables/symbols without them possibly "clashing" or "polluting" the global namespace. | Basically, namespaces make it possible to have identically named variables/symbols without them possibly "clashing" or "polluting" the global namespace. | ||
Before namespaces were used, there were only "global variables", so whenever some piece of code referred to a variable, it was possible to clash with some other similar or even unrelated uses of the variable (imagine a counter variable): | Otherwise, you would have to use different symbols with explicit naming conventions, such as: | ||
house1_bath | |||
house2_bath | |||
house3_bath | |||
These naming conventions can become awkward pretty quickly. | |||
Before namespaces were used, there were only such "global variables", so whenever some piece of code referred to a variable, it was possible to clash with some other similar or even unrelated uses of the variable (imagine a counter variable): | |||
That's when people started providing a surrounding "context" to embed variables properly. | That's when people started providing a surrounding "context" to embed variables properly. | ||
| Line 30: | Line 39: | ||
} | } | ||
Here, x is declared to be specific to the "hello" function and its namespace. | |||
In Nasal, a namespace is just a conventional hash: | |||
var foo = {}; | |||
To add members or fields to this "context" (or namespace), you can use several different notations: | |||
foo.altitude = 100; | |||
foo["altitude"] = 100; | |||
or even specify fields during initialization: | |||
var foo = { altitude:100 }; | |||
In order to access these fields or "members" of a namespace, you need to provide the valid namespace first: | |||
print ( foo.altitude ); | |||
So, basically namespaces are all about organizing and structuring your variables and the overall symbol space. | So, basically namespaces are all about organizing and structuring your variables and the overall symbol space. | ||
| Line 53: | Line 79: | ||
Obviously, this will only work if the switch off routine (method!) has some house to work with. The class itself really is just a "template" for functionality, before it can be used it needs to be instantiated, i.e. a new object must be created using the template, and then the member functions (methods) can be called. | Obviously, this will only work if the switch off routine (method!) has some house to work with. The class itself really is just a "template" for functionality, before it can be used it needs to be instantiated, i.e. a new object (house) must be created using the template, and then the member functions (methods) can be called for that object. | ||