Search results
Results from the WOW.Com Content Network
Making a shallow copy of a const or immutable value removes the outer layer of immutability: Copying an immutable string (immutable(char[])) returns a string (immutable(char)[]). The immutable pointer and length are being copied and the copies are mutable. The referred data has not been copied and keeps its qualifier, in the example immutable.
In computer science, string interning is a method of storing only one copy of each distinct string value, which must be immutable. [1] Interning strings makes some string processing tasks more time-efficient or space-efficient at the cost of requiring more time when the string is created or interned.
Python supports a wide variety of string operations. Strings in Python are immutable, so a string operation such as a substitution of characters, that in other programming languages might alter the string in place, returns a new string in Python. Performance considerations sometimes push for using special techniques in programs that modify ...
In many object-oriented languages such as Python, even primitive types such as integer numbers are objects. To avoid the overhead of constructing a large number of integer objects, these objects get reused through interning. [2] For interning to work the interned objects must be immutable, since state is shared between multiple variables.
In other languages, such as Java, JavaScript, Lua, Python, and Go, the value is fixed and a new string must be created if any alteration is to be made; these are termed immutable strings. Some of these languages with immutable strings also provide another type that is mutable, such as Java and .NET 's StringBuilder , the thread-safe Java ...
Mutable (non-const) operations can then be implemented in such a way that they create new objects instead of modifying the existing ones. This approach is characteristic of functional programming and is also used by the string implementations in Java, C#, and Python. (See Immutable object.)
In a number of object-oriented languages, there is the concept of an immutable object, which is particularly used for basic types like strings; notable examples include Java, JavaScript, Python, and C#. These languages vary in whether user-defined types can be marked as immutable, and may allow particular fields (attributes) of an object or ...
The main difference between an arbitrary data structure and a purely functional one is that the latter is (strongly) immutable. This restriction ensures the data structure possesses the advantages of immutable objects: (full) persistency, quick copy of objects, and thread safety.