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diff --git a/content/learn/07.structures/default.md b/content/learn/07.structures/default.md new file mode 100644 index 0000000..a87af08 --- /dev/null +++ b/content/learn/07.structures/default.md @@ -0,0 +1,201 @@ +--- +menuTitle: Structures +title: "Structuring the Data" +weight: 7 +--- +In [the previous step](/learn/pointers), we added pointers, which made it +possible to change data from other contexts/sequences. As we add more and more +data, it becomes clear that some structuring is needed. + +Structures are types. Types must be declared before being used. This also +prevents recursive types. + +The fields of a structure are initialized at the same time as the structure. + +Fields of a structure can be accessed in two ways: using the +`struct_var.field_name` notation, or the `(field struct_var field_name)` one. +If `struct_ptr` is a pointer to a structure, `struct_ptr.field_name` will also +work. + +To set the value of a structure's fields, one can use the `set` instruction or, +to set multiple fields at once, the `set_fields!` one. Note that omitting the +`!` at the end of `set_fields` is also valid Fate, but performs a computation +instead of a instruction: the structure is not modified, but a copy with the +modifications performed is returned. + +**data.fate:** + + (fate_version 1) + + (declare_structure weapon + (text name) + (int attack) + (int precision) + ) + + (declare_structure armor + (text name) + (int defense) + ) + + (declare_structure character + (string name) + (int money) + (weapon weapon) + (armor armor) + ) + + (global character hero) + + (set_fields! hero.weapon + (name (text "Legendary" sword)) + (attack 3) + (precision 50) + ) + + (set_fields! hero.armor + (name (text "Refined" attire)) + (defense 1) + ) + + (set hero.money 42) + +* `(text "Refined" attire)` generates a `text` value containing a textual + representation of the values passed as parameter. `"Refined" attire` is, by + itself, a `string`, and thus incompatible with the `text` field without a + conversion taking place. +* Because `hero_money` and `hero_name` have been removed in favor of a + structure, they should be replaced in the other files by `hero.money` and + `hero.name`. + +With this, it is time for our hero to get some proper gear, [let's see what +collection is available at the smithy](/learn/collections). + +---- + +## (Mostly) Unchanged Files + +**get_a_refill.fate:** + + (fate_version 1) + + (require data.fate) + (require actions.fate) + + (define_sequence lower_price_of_booze + ( + ((ptr int) price_pointer) + (int decrease) + ) + Great! The price of booze just lowered from (at price_pointer) + (set (at price_pointer) + (- + (at price_pointer) + (var decrease) + ) + ) + to (at price_pointer)! + ) + + (define_sequence get_a_refill () + (local int price_of_booze) + + (set price_of_booze 12) + + Staring straight at the barman, you raise your glass and proclaim: + (newline) + "This soon-to-be world savior needs more booze!" + (newline) + The barman's lack of reaction is disappointing, but seeing the beer + being poured does help improve the mood. + (newline) + Satisfied, you hand the barman (var price_of_booze) copper coins. + (visit pay (var price_of_booze)) + (newline) + The barman sighs, then asks: + (prompt_string (ptr hero.name) 2 64 What is your name, then, hero?) + (var hero.name)? + (newline) + The barman looks surprised. + (newline) + (visit lower_price_of_booze (ptr price_of_booze) 4) + (newline) + "I have heard of you, (var hero.name)," the barman exclaims, "I have + a quest for you!" + (newline) + It's your turn to sigh. + (newline) + The barman hands you a bag, and says: + (newline) + "Take this pre-payment and head to the smithy." + (newline) + ) + +**actions.fate:** + + (fate_version 1) + + (require data.fate) + + (define_sequence pay ( (int cost) ) + (set hero_money + (- (var hero.money) (var cost)) + ) + ) + +**falling_asleep.fate:** + + (fate_version 1) + + (require data.fate) + + (define_sequence fall_asleep () + Deciding to break away from the expected storyline, you promptly + fall asleep. + (newline) + ... + (newline) + Upon waking up, your hard-trained reflexes inform you that someone + stole all your money. + (set hero.money 0) + (newline) + This set-back was more than you could take. You give up on this + barely coherent story. + (end) + ) + +**main.fate:** + + (fate_version 1) + + Once upon a time, starting a story with these words wasn't considered + a cliche. Starting in a tavern might also not be seen as very + original. Having the main character be an street orphan, raised by + some mysterious sage all to end up as a mercenary with an uncommonly + strong sense of honor probably isn't going to lead to any praises for + novelty either. Maybe you should drink to that. + (newline) + Or maybe you shouldn't. This isn't your first mug. Not your second + either. Drinking to forget that you are a stereotypical hero isn't + going to solve anything. Worse, the alcoholic trait is part of the + image. + (newline) + As you contemplate your own pointless description, your gaze leaves + what turns out to be an already empty glass in your hand and finds the + barman. + + (player_choice + ( + ( Ask the barman for a refill ) + (visit get_a_refill) + ) + ( + ( Fall asleep ) + (jump_to fall_asleep) + ) + ) + + (require get_a_refill.fate) + (require falling_asleep.fate) + + (end) |