Today's session was short but packed full of data types and looooops 🔁
Yesterday's questions answered
- The
::
operator is used to access associated functions and associated constants fromcrates
ormods
. It can also be used to access constants, functions or static methods from structs or enums. - The
.
operator is used to access fields and methods of a struct or enum. These methods cannot be static methods. - Double character operators are logical operators whereas single character operates are bitwise operators and work only with integer operands.
-
match
expressions are the only context where=>
is valid Rust - The only other kind of limitations for the right side of a
match arm
is that the code is an expression. -
macros
are functions that write Rust code. They can take a variable number of parameters. They can implement traits becausemacros
are expanded at compile time. - Type annotations aren't strictly required if there is implicit type.
Today's open questions
- What are common patterns for using
String
vs.&str
? - When would you use a
loop
instead offor
orwhile
? - What data types require
.iter()
in afor
loop? - Do
vector
types have other advantages over arrays other than extendability? - Are
tuple
types technically indexed? Or why can't I slice atuple
? - Do I keep my target folder in version control (probably not)?
Rust got me loopy
Unlike Go
, Rust has a few different ways to loop. These are outlined below.
For loop
Python programmers like me can code for
loops by muscle memory. So there wasn't too much new here to learn. The only major difference is that some data types seem to require you to explicitly call an iter()
method, while others don't. I'm going to follow up on this in my next post.
While loop
The near omnipresent while
loop also features in Rust. Nothing much to say here...
Loop loop
Rust also offers a loop
loop. A loop
offers no boolean check per iteration like while
loop. Nor does it offer the value provided by an object's iter()
method as in a for
loop. So far I've only seen rudimentary usage using an index counter. I'll explore its uses more in the next post.
Collection basics
Array
No surprises here, but Rust does indeed support Arrays, which are ordered and have a fixed size. Elements of an array must be of the same type, and we can slice arrays using square brackets.
Vectors
The vector type is similar to an array, only that it is extendable. They support index slicing like arrays and have additional methods like dedup()
which removes duplicates. I'm not sure what the nuances of this data type are - I'll shed more light tomorrow.
Tuples
No other programming language that I've studied (which isn't many) has supported tuples. Tuples are arrays of fixed sized that can contain elements of different types. Tuples don't support index slicing, but instead can use dot notation to access elements. I want to understand why this is the case, so I'll put that into tomorrow's article.
String city
Strings in rust can be easily converted between characters and bytes. Single characters wrapped in single quotes are considered characters rather than strings.
&str
Literal strings in Rust are known as string slices. I presume this is a lower-level implementation and need only be used in cases where performance optimisations are important.
String
The more common string type is String
, which is a struct that implements static methods to yield String
types from string literals. You can call the push
or push_str
methods on a String
to add new chars or strings to it. Alternatively, you can use the +
operator.
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