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Done structs
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1 changed files with 188 additions and 15 deletions
203
Day_5/Day_5.jl
203
Day_5/Day_5.jl
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@ -20,56 +20,145 @@ Julia as a functional language does not have classes like in object oriented lan
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Using structs, you can define your own types. Structs use type composition. This means that you combine types into a new one.
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In Julia, type annotations DO NOT lead to any performance boosts. Structs build an exception! If you are writing a struct, you have to use type annotations with concrete types (not abstract)!
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In Julia, type annotations DO NOT lead to any performance boosts. Structs build an **exception**! If you are writing a struct, you have to use type annotations with **concrete types** (not abstract)!
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"""
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# ╔═╡ 3e3e324d-5650-4f81-87cf-fb0f6f55d9d1
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# You should not use a struct for a 2D vector. Use Julia's vectors! This is only for demonstration.
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struct Vec2d
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x::Float64
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y::Float64
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end
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# ╔═╡ 2ab6f97f-8eed-4b86-9eb6-1de88e6c846d
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vec_2d = Vec2d(1.0, 1.0)
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# Define a variable with this type.
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# The order of the arguments is important!
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# The first argument sets the first field (here `x`).
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# The second argument sets the second field and so on.
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vec_2d = Vec2d(1.0, 2.0)
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# ╔═╡ c9be354a-d5ef-4c94-ad2f-c2035dc9323f
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# Access a field
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vec_2d.x
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# ╔═╡ 48d31ed6-c5b7-4510-9c49-de8a3a8a0fa7
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vec_2d.y
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# ╔═╡ 377a9100-efd8-479c-b9f6-68584c886800
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# It is a new type
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typeof(vec_2d)
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# ╔═╡ 9940a716-1109-46f9-a88a-29a7a996412d
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md"""
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## Structs with abstract types
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"""
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# ╔═╡ 0e62a7b2-0636-4018-b005-0ae674fec45e
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# Wow, we did reach infinity ♾️
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# This is because of the limits of Float64
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Vec2d(factorial(big(1000)), 2.0)
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# ╔═╡ 70bb19db-3d97-4ae1-92d8-552574aa53c3
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md"""
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You might think this problem can be fixed by changing the type of the fields from `Float64` to something like `Real`. This will work, but it does harm performance!
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**One more important performance tip: Don't use structs with abstract field types (or no types)!**
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"""
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# ╔═╡ 6046417c-460b-4b0c-8423-4d6c4c18731f
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# Bad usage of abstract field types
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struct BadVec2d
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x::Real
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y::Real
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end
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# ╔═╡ 3e21d34f-3758-427f-85c0-7c457f3f0904
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# It does work, but it is bad for performance
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bad_vec2d = BadVec2d(factorial(big(1000)), 2.0)
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# ╔═╡ 4a07f5e3-2413-49c4-824c-b9c844695052
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# The type does not say anything about what the fields type is.
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typeof(bad_vec2d)
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# ╔═╡ 9008b1c4-ad76-4d4f-b6c5-001a77543b97
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# Better for performance:
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# Use this syntax to let the type be derived from an abstract type
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struct BetterVec2d{T<:Real}
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x::T
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y::T
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end
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# ╔═╡ 830dd737-4fdc-42c7-b105-d0622b055db1
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# This works too and it is good for performance
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big_vec2d = BetterVec2d(factorial(big(1000)), big(1))
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# ╔═╡ f91b0c58-bc44-414a-b357-145d8c4339d2
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# You see that a concrete type was choosen!
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typeof(big_vec2d)
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# ╔═╡ 169de33e-cff8-4419-be18-0f487c185ad7
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# The concrete type of the fields is determined on construction
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typeof(BetterVec2d(1.0, 2.0))
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# ╔═╡ 3f1b8df9-104b-42c3-97ee-11782f9f744f
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# This will not work. Both fields has to have the same type.
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# BetterVec2d(1.0, 1)
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# ╔═╡ a053b367-f7f2-440e-b9e0-4987b491c256
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struct MixedVec2d{T1<:Real, T2<:Real}
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x::T1
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y::T2
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end
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# ╔═╡ 1eab61c9-74e1-4540-9750-6ec8448e4950
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# This works
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mixed_vec2d = MixedVec2d(1.0, 1)
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# ╔═╡ 4a24f24b-d872-4cd8-bf76-49a0496e4ea6
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# Two different concrete types for the fields
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typeof(mixed_vec2d)
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# ╔═╡ c9f68fcf-2b20-43b1-839a-59805357c6d3
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md"""
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## Mutation
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By default, structs are not mutable!
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If you want to be mutable, you have to use the keyword `mutable`.
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"""
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# ╔═╡ f8b27d41-448a-4329-986f-e65e0b3e77d6
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# This will not work because the struct is immutable by default
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# vec_2d.x = 42.0
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# ╔═╡ da9e39a5-0ee3-4f6c-8cb1-abb3ebf3a01e
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# Defining a mutable struct
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mutable struct MutVec2d
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x::Float64
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y::Float64
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end
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# ╔═╡ d16ac12a-c772-4fee-a309-5b4a2708d08e
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begin
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mut_vec = MutVec2d(1.0, 2.0)
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# Mutating a field
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mut_vec.x = 42.0
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mut_vec
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end
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# ╔═╡ d635a63b-44d9-4bfc-a873-ef537cdbdb09
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md"""
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## Structs from abstract types
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To use the features of mutliple dispatch, define an abstract type and derive structs from it.
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"""
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# ╔═╡ 10c380fd-80e6-4cb7-b50e-1a7998ec00c5
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# Defining an abstract type
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abstract type Student end
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# ╔═╡ 58de483d-c2b5-4252-b6da-64bd8bfac1ac
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# Defining a struct derived from the abstract type `Student`
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struct MathStudent<:Student
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name::String
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hobby::String
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@ -79,10 +168,11 @@ end
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struct PhysicsStudent<:Student
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name::String
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hobby::String
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favorite_particle::String
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favorite_particle::String # Some additional field
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end
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# ╔═╡ b535fd1d-695d-49fb-8a6a-2f2f0053a6f6
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# Define a function that works on all students
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function print_name(student::Student)
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println(student.name)
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@ -90,17 +180,19 @@ function print_name(student::Student)
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end
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# ╔═╡ 63f32169-b98c-4212-bbd9-4c601266f209
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# Define a method that works only with math students
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function print_information(math_student::MathStudent)
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println("Math student: $(math_student.name)")
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println("hobby: $(math_student.hobby)")
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println("Hobby: $(math_student.hobby)")
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return
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end
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# ╔═╡ cb49717b-0584-430e-a30c-c4d02cf55eb2
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# Define a method that works only with physics students
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function print_information(physics_student::PhysicsStudent)
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println("Physics student: $(physics_student.name)")
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println("hobby: $(physics_student.hobby)")
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println("Hobby: $(physics_student.hobby)")
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println("Favorite particle: $(physics_student.favorite_particle)")
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return
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@ -124,10 +216,70 @@ print_information(math_student)
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# ╔═╡ bc8ef92b-1c68-4c9d-948a-6196dcd2b378
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print_information(physics_student)
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# ╔═╡ d8a2ae5c-b42a-4673-9a95-24cfc69ea3e7
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# ╔═╡ 06805ff8-f4bc-4779-baa9-2801a44407b6
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md"""
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# Writing documentation
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## Constructors
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You can either define new constructors for a struct or overwrite the default constructor.
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"""
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# ╔═╡ d1937187-15b0-46e7-9589-05d2349aa93a
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# `begin` blocks are only needed in Pluto notebooks
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begin
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struct ComputerScienceStudent<:Student
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name::String
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hobby::String
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end
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# Defining an additional constructor to the default constructor
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function ComputerScienceStudent(name)
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return ComputerScienceStudent(name, "Programming")
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end
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end
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# ╔═╡ 721e268d-b7c5-4ea8-b4d7-2bab6e2a6fb0
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# Using the default constructor
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ComputerScienceStudent("John", "Tennis")
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# ╔═╡ 0f76bd6b-906f-49b3-8a36-9e02feb750b9
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# Using the additional constructor
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ComputerScienceStudent("Selina")
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# ╔═╡ 513a4b3f-5b12-4d65-9321-0c883f12a1eb
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mutable struct BiologyStudent<:Student
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name::String
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hobby::String
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# Overwriting the default constructor
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# You have to use the keyword `new`
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function BiologyStudent(name)
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return new(name, "Observing animals")
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end
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end
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# ╔═╡ 3063d330-c411-431e-9e7a-eb3f5cd3ee7b
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# This will not work because the default constructor is overritten!
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# BiologyStudent("Kate", "Swimming")
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# ╔═╡ 9e621eb5-a163-4a7a-abd5-85bdf9469692
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# The new default constructor
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BiologyStudent("Kate")
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# ╔═╡ 44511b7e-a38a-450f-9a55-b6b6a4d3edd5
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# This is the default constructor now
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begin
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biology_student = BiologyStudent("Kate")
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# The struct has to be mutable
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biology_student.hobby = "Swimming"
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biology_student
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end
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# ╔═╡ eddfd543-091b-4a32-8124-a67687dcf457
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md"""
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Why would you want to overwrite the default constructor?
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It is useful if you want to enforce checking fields before construction.
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"""
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# ╔═╡ c24c04e4-b131-11ec-2c1b-7de12fe0c324
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@ -187,11 +339,6 @@ md"""
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## `DifferentialEquations.jl`
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"""
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# ╔═╡ b621819d-6ce3-41e1-9e61-3ad0a2c9b016
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md"""
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## `Intervals.jl`
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"""
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# ╔═╡ 0174178f-3ed9-4890-8482-714cb51a635d
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md"""
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## `ProgressMeter.jl`
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@ -202,6 +349,11 @@ md"""
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## `NaturallyUnitful.jl`
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"""
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# ╔═╡ 097b1b98-8b98-4160-bf31-d982f21ab8d6
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md"""
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## `Symbolics.jl`
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"""
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# ╔═╡ 2430f309-be28-4bc2-9692-92489c31f7b2
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md"""
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# Resources
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"""
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# ╔═╡ Cell order:
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# ╠═c7256818-f2ab-4f8a-be6f-1d2c97dca981
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# ╟─c7256818-f2ab-4f8a-be6f-1d2c97dca981
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# ╠═3e3e324d-5650-4f81-87cf-fb0f6f55d9d1
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# ╠═c9be354a-d5ef-4c94-ad2f-c2035dc9323f
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# ╠═48d31ed6-c5b7-4510-9c49-de8a3a8a0fa7
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# ╠═377a9100-efd8-479c-b9f6-68584c886800
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# ╟─9940a716-1109-46f9-a88a-29a7a996412d
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# ╠═0e62a7b2-0636-4018-b005-0ae674fec45e
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# ╟─70bb19db-3d97-4ae1-92d8-552574aa53c3
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# ╠═6046417c-460b-4b0c-8423-4d6c4c18731f
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# ╠═3e21d34f-3758-427f-85c0-7c457f3f0904
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# ╠═4a07f5e3-2413-49c4-824c-b9c844695052
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# ╠═9008b1c4-ad76-4d4f-b6c5-001a77543b97
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# ╠═830dd737-4fdc-42c7-b105-d0622b055db1
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# ╠═f91b0c58-bc44-414a-b357-145d8c4339d2
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# ╠═169de33e-cff8-4419-be18-0f487c185ad7
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# ╠═3f1b8df9-104b-42c3-97ee-11782f9f744f
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# ╠═a053b367-f7f2-440e-b9e0-4987b491c256
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# ╠═1eab61c9-74e1-4540-9750-6ec8448e4950
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# ╠═4a24f24b-d872-4cd8-bf76-49a0496e4ea6
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# ╟─c9f68fcf-2b20-43b1-839a-59805357c6d3
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# ╠═f8b27d41-448a-4329-986f-e65e0b3e77d6
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# ╠═da9e39a5-0ee3-4f6c-8cb1-abb3ebf3a01e
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# ╠═d16ac12a-c772-4fee-a309-5b4a2708d08e
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# ╟─d635a63b-44d9-4bfc-a873-ef537cdbdb09
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# ╠═10c380fd-80e6-4cb7-b50e-1a7998ec00c5
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# ╠═58de483d-c2b5-4252-b6da-64bd8bfac1ac
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# ╠═4024358d-f673-45f1-a12a-00a5554622e3
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# ╠═bc43e76c-3a9b-4f3f-9f88-28f2f7f868d1
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# ╠═0a2619e4-9eed-4eb3-a411-c616ee840062
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# ╠═bc8ef92b-1c68-4c9d-948a-6196dcd2b378
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# ╠═d8a2ae5c-b42a-4673-9a95-24cfc69ea3e7
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# ╟─06805ff8-f4bc-4779-baa9-2801a44407b6
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# ╠═d1937187-15b0-46e7-9589-05d2349aa93a
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# ╠═721e268d-b7c5-4ea8-b4d7-2bab6e2a6fb0
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# ╠═0f76bd6b-906f-49b3-8a36-9e02feb750b9
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# ╠═513a4b3f-5b12-4d65-9321-0c883f12a1eb
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# ╠═3063d330-c411-431e-9e7a-eb3f5cd3ee7b
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# ╠═9e621eb5-a163-4a7a-abd5-85bdf9469692
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# ╠═44511b7e-a38a-450f-9a55-b6b6a4d3edd5
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# ╟─eddfd543-091b-4a32-8124-a67687dcf457
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# ╟─c24c04e4-b131-11ec-2c1b-7de12fe0c324
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# ╠═279d81e7-77d5-4855-bf45-a1a613265f65
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# ╠═62e2481a-3fa1-4f2f-a7b6-7879c675701d
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# ╠═eb836cdc-de12-430c-a6f3-1524ebd28865
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# ╠═7e75da58-f110-41cb-ab19-79376370965f
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# ╠═6b417e5d-01c2-4b06-9708-62c422a6b64b
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# ╠═b621819d-6ce3-41e1-9e61-3ad0a2c9b016
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# ╠═0174178f-3ed9-4890-8482-714cb51a635d
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# ╠═d29338b3-3c25-4ae4-90d0-1176538c635e
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# ╟─c7e76680-571e-427d-a564-8819df8b3750
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# ╟─00000000-0000-0000-0000-000000000001
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