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Common Mistakes - Italian translation added

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_it/quality/common_mistakes.md
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@ -1,72 +1,67 @@
--- ---
title: Common Mistakes title: Errori comuni
layout: default layout: default
root: ../.. root: ../..
idx: 8.1 idx: 8.1
redirect_from: /en/chapters/common_mistakes.html redirect_from: /it/chapters/common_mistakes.html
--- ---
## Introduction <!-- omit in toc --> ## Introduzione <!-- omit in toc -->
This chapter details common mistakes, and how to avoid them. Questo capitolo illustra gli errori più comuni e come evitarli.
- [Never Store ObjectRefs (ie: players or entities)](#never-store-objectrefs-ie-players-or-entities) - [Non salvare mai ObjectRef (giocatori ed entità)](#non-salvare-mai-objectref-giocatori-ed-entita)
- [Don't Trust Formspec Submissions](#dont-trust-formspec-submissions) - [Non fidarti dei campi dei formspec](#non-fidarti-dei-campi-dei-formspec)
- [Set ItemStacks After Changing Them](#set-itemstacks-after-changing-them) - [Imposta gli ItemStack dopo averli modificati](#imposta-gli-itemstack-dopo-averli-modificati)
## Never Store ObjectRefs (ie: players or entities) ## Non salvare mai ObjectRef (giocatori ed entità)
If the object an ObjectRef represents is deleted - for example, if the player goes Se l'oggetto rappresentato da un ObjectRef viene rimosso - per esempio quando il giocatore si disconnette o un'entità viene rimossa dalla memoria - chiamare metodi su quell'oggetto causerà la chiusura improvvisa del server (*crash*).
offline or the entity is unloaded - then calling methods on that object
will result in a crash.
For example, don't do this: Sbagliato:
```lua ```lua
minetest.register_on_joinplayer(function(player) minetest.register_on_joinplayer(function(player)
local function func() local function func()
local pos = player:get_pos() -- BAD! local pos = player:get_pos() -- MALE!
-- `player` is stored then accessed later. -- `player` viene salvato per essere utilizzato dopo.
-- If the player leaves in that second, the server *will* crash. -- Se il giocatore si disconnette, il server crasha
end end
minetest.after(1, func) minetest.after(1, func)
foobar[player:get_player_name()] = player foobar[player:get_player_name()] = player
-- RISKY -- RISCHIOSO
-- It's not recommended to do this. -- Non è consigliato fare così.
-- Use minetest.get_connected_players() and -- Usa invece minetest.get_connected_players() e minetest.get_player_by_name().
-- minetest.get_player_by_name() instead.
end) end)
``` ```
Do this instead: Giusto:
```lua ```lua
minetest.register_on_joinplayer(function(player) minetest.register_on_joinplayer(function(player)
local function func(name) local function func(name)
-- Attempt to get the ref again -- Tenta di ottenere il riferimento
local player = minetest.get_player_by_name(name) local player = minetest.get_player_by_name(name)
-- Check that the player is still online -- Controlla che il giocatore sia online
if player then if player then
-- Yay! This is fine -- è online, procedo
local pos = player:get_pos() local pos = player:get_pos()
end end
end end
-- Pass the name into the function -- Passa il nome nella funzione
minetest.after(1, func, player:get_player_name()) minetest.after(1, func, player:get_player_name())
end) end)
``` ```
## Don't Trust Formspec Submissions ## Non fidarti dei campi dei formspec
Malicious clients can submit formspecs whenever they like, with Client malevoli possono compilare i campi nei formspec quando vogliono, con qualsiasi contenuto vogliono.
whatever content they like.
For example, the following code has a vulnerability which allows players to Per esempio, il seguente codice presenta una vulnerabilità che permette ai giocatori di assegnarsi da soli il privilegio di moderatore:
give themselves moderator privileges:
```lua ```lua
local function show_formspec(name) local function show_formspec(name)
@ -76,15 +71,15 @@ local function show_formspec(name)
minetest.show_formspec(name, "modman:modman", [[ minetest.show_formspec(name, "modman:modman", [[
size[3,2] size[3,2]
field[0,0;3,1;target;Name;] field[0,0;3,1;target;Nome;]
button_exit[0,1;3,1;sub;Promote] button_exit[0,1;3,1;sub;Promuovi]
]]) ]])
return true return true
}) })
minetest.register_on_player_receive_fields(function(player, minetest.register_on_player_receive_fields(function(player,
formname, fields) formname, fields)
-- BAD! Missing privilege check here! -- MALE! Manca il controllo dei privilegi!
local privs = minetest.get_player_privs(fields.target) local privs = minetest.get_player_privs(fields.target)
privs.kick = true privs.kick = true
@ -94,7 +89,7 @@ minetest.register_on_player_receive_fields(function(player,
end) end)
``` ```
Add a privilege check to solve this: Aggiungi un controllo dei privilegi per ovviare:
```lua ```lua
minetest.register_on_player_receive_fields(function(player, minetest.register_on_player_receive_fields(function(player,
@ -107,61 +102,51 @@ minetest.register_on_player_receive_fields(function(player,
end) end)
``` ```
## Set ItemStacks After Changing Them ## Imposta gli ItemStack dopo averli modificati
Have you noticed that it's simply called an `ItemStack` in the API, not an `ItemStackRef`, Se ci si fa caso, nella documentazione si parla di `ItemStack` e non `ItemStackRef`.
similar to `InvRef`? This is because an `ItemStack` isn't a reference - it's a Questo perché gli ItemStack NON sono un riferimento, bensì una copia.
copy. Stacks work on a copy of the data rather than the stack in the inventory. Questo vuol dire che modificando la copia, non si modificherà in automatico anche l'originale.
This means that modifying a stack won't actually modify that stack in the inventory.
For example, don't do this: Sbagliato:
```lua ```lua
local inv = player:get_inventory() local inv = player:get_inventory()
local stack = inv:get_stack("main", 1) local pila = inv:get_stack("main", 1) -- lo copio
stack:get_meta():set_string("description", "Partially eaten") pila:get_meta():set_string("description", "Un po' smangiucchiato")
-- BAD! Modification will be lost -- MALE! Le modifiche saranno perse
``` ```
Do this instead: Giusto:
```lua ```lua
local inv = player:get_inventory() local inv = player:get_inventory()
local stack = inv:get_stack("main", 1) local pila = inv:get_stack("main", 1) -- lo copio
stack:get_meta():set_string("description", "Partially eaten") pila:get_meta():set_string("description", "Un po' smangiucchiato")
inv:set_stack("main", 1, stack) inv:set_stack("main", 1, pila)
-- Correct! Item stack is set -- Corretto! L'ItemStack è stato cambiato con la copia
``` ```
The behaviour of callbacks is slightly more complicated. Modifying an `ItemStack` you Il comportamento dei callback è leggermente più complicato.
are given will change it for the caller too, and any subsequent callbacks. However,
it will only be saved in the engine if the callback caller sets it.
```lua ```lua
minetest.register_on_item_eat(function(hp_change, replace_with_item, minetest.register_on_item_eat(function(hp_change, replace_with_item,
itemstack, user, pointed_thing) itemstack, user, pointed_thing)
itemstack:get_meta():set_string("description", "Partially eaten") itemstack:get_meta():set_string("description", "Un po' smangiucchiato")
-- Almost correct! Data will be lost if another -- Quasi corretto! I dati saranno persi se un altro callback annulla questa chiamata
-- callback cancels the behaviour
end) end)
``` ```
If no callbacks cancel this, the stack will be set and the description will be updated, Se nessun callback cancella l'operazione, la pila sarà impostata e la descrizione aggiornata; ma se un callback effettivamente cancella l'operazione, l'aggiornamento potrebbe andar perduto.
but if a callback does cancel this, then the update may be lost.
It's better to do this instead: È meglio quindi fare così:
```lua ```lua
minetest.register_on_item_eat(function(hp_change, replace_with_item, minetest.register_on_item_eat(function(hp_change, replace_with_item,
itemstack, user, pointed_thing) itemstack, user, pointed_thing)
itemstack:get_meta():set_string("description", "Partially eaten") itemstack:get_meta():set_string("description", "Un po' smangiucchiato")
user:get_inventory():set_stack("main", user:get_wield_index(), user:get_inventory():set_stack("main", user:get_wield_index(),
itemstack) itemstack)
-- Correct, description will always be set! -- Corretto! La descrizione verrà sempre aggiornata
end) end)
``` ```
If the callbacks cancel or the callback runner doesn't set the stack,
then the update will still be set.
If the callbacks or the callback runner set the stack, then the use of
set_stack doesn't matter.