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becki:linux:golang [2011-11-07 14:32] becki |
becki:linux:golang [2018-02-26 11:24] (aktuell) becki |
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* Arrays are copied by value :!: | * Arrays are copied by value :!: | ||
* A Pointer to an array is possible (unlike in C where the pointer represents the array) | * A Pointer to an array is possible (unlike in C where the pointer represents the array) | ||
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</note> | </note> | ||
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<note tip> | <note tip> | ||
- | |||
* Slices are copied //by value// but the internal arrays are copied //by reference// :!: | * Slices are copied //by value// but the internal arrays are copied //by reference// :!: | ||
* Slices have a length (number of items) and a capacity (length of underlying array(?)) | * Slices have a length (number of items) and a capacity (length of underlying array(?)) | ||
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</note> | </note> | ||
<note important>Appending to a Slice results in a new slice. The new slice may point to a different array than the original slice.</note> | <note important>Appending to a Slice results in a new slice. The new slice may point to a different array than the original slice.</note> | ||
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* In order to really work on the object, the receiver of the method must be a //pointer// to the object, otherwise the method operates ony on an (anonymous) copy. | * In order to really work on the object, the receiver of the method must be a //pointer// to the object, otherwise the method operates ony on an (anonymous) copy. | ||
* Invoking methods on //pointers to objects// has the same syntax and work the same as invoking the method directly on the object. | * Invoking methods on //pointers to objects// has the same syntax and work the same as invoking the method directly on the object. | ||
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</note> | </note> | ||
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* Implement the methods of the interface with an object //pointer// as receiver | * Implement the methods of the interface with an object //pointer// as receiver | ||
* Instantiate the interface with the //adress// of the object | * Instantiate the interface with the //adress// of the object | ||
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</note> | </note> | ||
<note important>Some :?: library functions which return an interface in reality return a pointer to an implementation of the interface (see e.g. [[golang>pkg/net/#Listener.Listen|net.Listen]])</note> | <note important>Some :?: library functions which return an interface in reality return a pointer to an implementation of the interface (see e.g. [[golang>pkg/net/#Listener.Listen|net.Listen]])</note> | ||
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===== Handling Errors == | ===== Handling Errors == | ||
- | Defer, Panic, Recover: http://blog.golang.org/2010_08_01_archive.html => The convention in the Go libraries is that even when a package uses panic internally, its external API still returns explicit ''os.Error'' values. | + | Defer, Panic, Recover: http://blog.golang.org/2010_08_01_archive.html ⇒ The convention in the Go libraries is that even when a package uses panic internally, its external API still returns explicit ''os.Error'' values. |
[[golang>pkg/os/#Error|os.Error]] is the same interface as [[golang>pkg/fmt/#Stringer|fmt.Stringer]], i.e. it has a method called ''String()'' wich returns a ''string''. Thus an instance of os.Error can always be passed to the functions in ''fmt'' and ''log'' directly, without explicitely calling the ''String()'' method. E.g: | [[golang>pkg/os/#Error|os.Error]] is the same interface as [[golang>pkg/fmt/#Stringer|fmt.Stringer]], i.e. it has a method called ''String()'' wich returns a ''string''. Thus an instance of os.Error can always be passed to the functions in ''fmt'' and ''log'' directly, without explicitely calling the ''String()'' method. E.g: |