79 lines
1.9 KiB
Markdown
79 lines
1.9 KiB
Markdown
# Structs
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In Tomo, you can define your own structs, which hold members with arbitrary
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types that can be accessed by fields:
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```tomo
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struct Foo(name:Text, age:Int)
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...
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>> my_foo := Foo("Bob", age=10)
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= Foo(name="Bob", age=10)
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>> my_foo.name
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= "Bob"
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```
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Structs are value types and comparisons on them operate on the member values
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one after the other.
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## Namespaces
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Structs can define their own methods that can be called with a `:` or different
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values that are stored on the type itself.
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```tomo
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struct Foo(name:Text, age:Int):
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oldest := Foo("Methuselah", 969)
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func greet(f:Foo):
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say("Hi my name is $f.name and I am $f.age years old!")
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func get_older(f:@Foo):
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f.age += 1
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...
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my_foo := @Foo("Alice", 28)
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my_foo:greet()
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my_foo:get_older()
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```
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Method calls work when the first argument is the struct type or a pointer to
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the struct type.
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## Secret Values
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If you want to prevent accidental leaking of sensitive information, you can
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create a struct with the `secret` flag turned on, which causes the struct to
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be converted to text without showing any of its contents:
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```tomo
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struct Password(raw_password_text:Text; secret)
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struct User(username:Text, password:Password)
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...
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user := User("Stanley", Password("Swordfish"))
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>> user
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= User(username="Stanley", password=Password(...))
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>> "$user" == 'User(username="Stanley", password=Password(...))'
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= yes
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```
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Designing APIs so they take secrecy-protected structs instead of raw data
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values is a great way to prevent accidentally leaking sensitive information in
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your logs! Secrecy-protected values still work the same as any other struct,
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they just don't divulge their contents when converting to strings:
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```tomo
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>> user.password == Password("Swordfish")
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= yes
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```
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You can also access the fields directly, but hopefully this extra amount of
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friction reduces the chances of accidentally divulging sensitive content:
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```tomo
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>> user.password
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= Password(...)
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>> user.password.raw_password_text
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= "Swordfish"
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```
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