Apple’s new Swift language provides support for a common data structure known as the tuple<\/i>. Unlike the venerable array and dictionary, however, what precisely a tuple is and how it behaves is different among programming languages. What do we mean by this?<\/p>\n
In Python you can get the number of elements in a tuple:<\/p>\n
In Python you typically cannot access the tuple elements by name, but do so by index:<\/p>\n There is<\/i> a mechanism for creating so-called named tuples in Python using the You can iterate over the elements in the tuple in Python:<\/p>\n Erlang provides a tuple datatype similar to that of Python: you can create arbitrary groups of data bundled together. In our previous example all of the elements in the tuple were of the same type, namely a string. This does not have to be the case. In Erlang:<\/p>\n Neither Python or Erlang allow you to change a given element member in the tuple, but for different reasons. In Erlang you can’t change the value of a variable once its been set, whereas in Python tuples are immutable (cannot change) types. To get around that in Erlang one might do:<\/p>\n In Python the following is effective:<\/p>\n Erlang does provide<\/i> named elements in a special type of tuple called a record<\/a><\/b>. <\/p>\n Now let’s turn to Swift tuples. We prefer using the REPL feature of Swift from the command line rather than using the Playground. See our previous post<\/a> if you aren’t familiar with using Swift from the terminal. Of course, you can also follow along in the Playground.<\/p>\n The first thing we notice is how Swift takes the tuple created and shows you what the constituent datatypes are. In this case our Unlike Python, Swift tuples support named<\/i> elements by default (that is, no need to use any special imports). This is handy for treating a tuple like a lightweight With this variable definition we can do this:<\/p>\n Also unlike Python, Swift tuples are mutable and we can change the constituent elements:<\/p>\n
\n$ python
\nPython 2.7.6 (default, May 30 2014, 22:21:15)
\n[GCC 4.2.1 Compatible Apple LLVM 6.0 (clang-600.0.34.2)] on darwin
\nType \"help\", \"copyright\", \"credits\" or \"license\" for more information.
\n>>> currentConditions = (\"Mostly Cloudy\", \"90\", \"9\")
\n>>> len(currentConditions)
\n3
\n<\/code><\/p>\n
\n>>> currentConditions[0]
\n'Mostly Cloudy'
\n<\/code><\/p>\ncollections<\/a><\/code> module. <\/p>\n
\n>>> for e in currentConditions:
\n... print e
\n...
\nMostly Cloudy
\n90
\n9
\n<\/code><\/p>\n
\n7> CurrentConditions = {\"Mostly Cloudy\", 90, 9}.
\n{\"Mostly Cloudy\",90,9}
\n<\/code><\/p>\n
\n11> UpdatedConditions = setelement(2,CurrentConditions,89).
\n{\"Mostly Cloudy\",89,9}
\n<\/code><\/p>\n
\n>>> cc = list(currentConditions)
\n>>> cc[1] = '89'
\n>>> currentConditions = tuple(cc)
\n<\/code><\/p>\n
\n$ swift -repl
\nWelcome to Swift! Type :help for assistance.
\n 1> var currentConditions = (\"Mostly Cloudy\", 89, 9)
\ncurrentConditions: (String, Int, Int) = {
\n 0 = \"Mostly Cloudy\"
\n 1 = 89
\n 2 = 9
\n}
\n<\/code><\/p>\ncurrentConditions<\/code> variable is a (String, Int, Int)<\/code> tuple. We can access the constituent members using a dot syntax<\/i> notation, which is in contrast to the bracket syntax<\/i> of Python:<\/p>\n
\n 2> currentConditions.0
\n$R1: String = \"Mostly Cloudy\"
\n<\/code><\/p>\nstruct<\/code>, commonly used in C and C++<\/a>.<\/p>\n
\n var currentConditions:(conditions:String, temperature:Int, wind:Int) = (\"Mostly Cloudy\", 89, 9)
\ncurrentConditions: (conditions: String, temperature: Int, wind: Int) = {
\n conditions = \"Mostly Cloudy\"
\n temperature = 89
\n wind = 9
\n}
\n<\/code><\/p>\n
\n 2> currentConditions.temperature
\n$R1: Int = 89
\n<\/code><\/p>\n
\n 3> currentConditions.temperature = 87
\n 4> currentConditions
\n$R3: (conditions: String, temperature: Int, wind: Int) = {
\n conditions = \"Mostly Cloudy\"
\n temperature = 87
\n wind = 9
\n}
\n<\/code><\/p>\n